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Made by CamBam => Members Projects => Topic started by: dave benson on September 21, 2017, 13:17:52 pm



Title: Automatic tool changer for the lathe
Post by: dave benson on September 21, 2017, 13:17:52 pm
   
   First Draft on a wireless bluetooth tool changer for my lathe
                                                     Dave Benson
                                       21/09/17

After building a CNC Lathe over the last two months, I've been thinking about
making a Automatic tool-changer.

I'm going to use a Arduino ATmega micro-controller with a Blue-Tooth Dongle so that there are no wires connected to the turret itself, It'll be totally self contained including a battery power pack with rechargeable batteries.

I've checked that Mach3 can communicate to the micro-controller through a tool change macro over a serial port and this is very easy to do.

I've looked at a few tool change macro's for automatic tool-changes on a mill and don't think there'll be any difficulty doing this for a Lathe.

It'll go something like this:

1. uncheck the Ignore tool-changes setting in Mach3
2. set the port eg. Com5 at 57600 baud
3. Before you run your G-code You'll have to Home the Tool-changer.
4. Then simply run your G-code and when a tool-change is called for the start and end macro's will be ran.
5. The start macro will simply send a request for a tool-change and a tool number  1 through 8 .
6. The controller will move to a defined G28 and engage the new tool position and send an acknowledgement that this has happened and that no errors were en-counted.
7. The end macro will either flag that an error has occurred  or restart mach3
to continue with the rest of the program.
   
Later on when the system works, I may save the tool number to the EEprom on the controller so that it doesn’t need to be homed.

I think I'm going to go with a Ratchet and Pawl system as this means that I only need one stepper motor and no breaking mechanism. This also means that the tool changer can only move in one direction but this won't mean much to me as this is not a production lathe.

The first pic is the bluetooth transceiver and the second is of a hub of a large ford front wheel assy which I'll take apart to see if it can be used as the turret body.

 Dave



Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on September 21, 2017, 13:25:19 pm
Dave,
Interesting !
If you are using s ratchet & pawl then a simple linear actuator would turn it


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 21, 2017, 13:38:22 pm
HI Eddy
I'm not sure yet, I looked at a lot of you tube vids on various builds, horizontal and vertical, I think at this
stage I'm leaning towards a pulley or gear bolted around the periphery of the plattern.

It would be nice to keep all the swarf out of the works though so an inline vertical position where the motor is integral to the unit would do that, I'm busy cading up lots of alternatives, so I'm not sure yet as to which way to go.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 21, 2017, 23:26:52 pm
HI Eddy

I did look into a linear actuator, a miniature one and will keep that in mind.

As this tool changer is going to be battery powered I'm going to great length's to save power, so an actuator that you can turn power off while not changing tools is the way to go, so even a solenoid might work.

I also looked at a Stepper motor with a gearbox that only drew 0.4 amps while on.

I also realised that a ratchet and pawl system is only workable for vertical tool changers.

The problem here, is finding the room to mount it vertically and still keep the working envelop of the machine the same.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 23, 2017, 01:53:29 am
A small update on the tool changer.
I've written the code for the tool changer for the micro-controller.

I've connected the micro-controller to a bluetooth module and have it talking to the pc through a bluetooth dongle.

I've spotted on youtube this Mach3 tool change screenset https://www.youtube.com/watch?v=f0de3r-EKos&t=126s (https://www.youtube.com/watch?v=f0de3r-EKos&t=126s)(which is very well done) and will soon write the tool change macro's for this tool changer.

I've dissembled the wheel hub and now I'm off to machine the tool change platen (six tools).

Dave 


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 25, 2017, 09:45:08 am
Another small update.
I've milled the hub to take the tools (6) and machined everything concentric.

Next I have to extend the shaft at the rear of the turret to take the pawl and attach the stepper motor.

The stepper I've ordered is a small Nema 17 with a 27 to one gearbox rated at 4 nm at 0.4 amps per phase.

I've ordered a shield for the Arduino compatible with blue-tooth.

I've discovered that the scripting language (Cyprus) has only a SendSerial function and not a receive, which would mean that in the marco I would send a tool change position and the wait a while, while the tool changer changes the tool rather that having some feedback that tell Mach3 that the tool was changed and everything was ok.

I've downloaded the SDK for Mach3 and am looking at doing the tool changing as a plugin that way, as you can get feedback from the tool-changer.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 28, 2017, 10:46:00 am
A little more progress.

I've made the ratchet and pawl, and have tested it's accuracy to index and hold center height.
I can't do much now until the stepper motor and the tooling arrives, so I've started on a plugin for mach3 as (plan A)
and developed a plan (B) using two arduino's master and slave HC-o5 and HC-06 bluetooth units with one connected to the serial port in case plan A go'es amiss.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 30, 2017, 14:19:25 pm
HI All

I've made some clamping wedges to hold the tools in the turret, and they work very well, once tightened up the tools are very rigidly held and I don't think the tools will work loose at all.

I've made progress on the plugin for Mach3, but still have a way to go yet.
I still have to write the tool change macro, but have been putting that off until the mach3 plugin is done and tested.

Dave
 


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 01, 2017, 18:48:13 pm
It looks like you making good progress. I'm looking forward to short video to see how it all works when the project is completed.


Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on October 01, 2017, 19:07:27 pm
It looks like you making good progress. I'm looking forward to short video to see how it all works when the project is completed.

+1


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 07, 2017, 02:32:25 am
Another small update
The stepper motor arrived yesterday (no motor shield or tools yet).

I've programmed the micro-controller for the Turret so I used a l298 stepper driver that I had on hand to test it out.
Because I want to battery power this turret, I had selected a 0.4 amps per phase motor and gearbox 3nm with a peak of 5nm.
I have set quite a bit of pre-load on the angular contact bearings and hoped the motor would drive it ok, and it does.

To give the motor a fighting chance I programmed a motion translator with a trapezoidal wave form, that is to say that it accelerates up to a preset velocity, motors along at that velocity  and then decelerates to a stop.

I've also used Full step "Alternate" mode to drive the motor (Both Phases on at all times).

I've also added to the code a Parking feature so that the pawl is tightened up against the ratchet after the move is complete and the backlash "from the couple-er" is compensated for.

I've uploaded a 30 second vid of the tools changing, Although the sound isn't very good, at the very end you can here the Acceleration/deceleration and parking feature happening.

Dave
https://youtu.be/Ktaylp2ilBY (https://youtu.be/Ktaylp2ilBY)


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 07, 2017, 13:29:07 pm
I like it!


Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on October 07, 2017, 22:14:53 pm
Nice job Dave !


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 11, 2017, 06:13:45 am
Another small update.
Two of the tool holders  turned up but not the rest (ordered the same day), so I've made the outer casing
and continued on with the plugin.
So now I can Start, Stop and Feed Hold Mach3 from the tool turret screen as well as home the turret and give it some manual commands like, home and move to tool and have finally got it to talk over the bluetooth module and able to pass commands back to Mach3 (I only wanted to do this to tell Mach3 that the tool was changed and it was ok to move on with the code or else halt and signal an error).

The two "threading tool holders" that turned up look nice, But I can see no way that left hand tool holder could work
as a threading tool holder, as the insert is pointing at the wrong orientation to cut effectively, so maybe you need to buy a different insert to suit.

Dave
 


Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on October 11, 2017, 12:26:40 pm
Dave,
The left-hand threading insert is often used for inside threading of tubular stock, and indeed, the inserts are defined as 'left hand', meaning the engagement angle is reversed from that of a right-handed tool.

LLoyd


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 11, 2017, 13:21:24 pm
Dave,
You not using Mach Turn to controll the lathe with tool changer?

The plugin looks good.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 12, 2017, 10:33:02 am
HI All

LLoyd you may be right about the tool holders, and I've examined the inserts am they look identical and the way, one of the the inserts fit in the holder, I'd have to have the holder fixed in the tool post at an odd angle.

Bubba I've got a few versions of Mach3 to test with (things changed over time in the software) and the one on the lathe is an older version. so I will test with that version at some stage.

here is a pic of the tool holders.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on October 12, 2017, 12:13:15 pm
Dave,
If the holders are mirror-images of one-another, but the actual inserts are not, then you do have a left-hand threading tool, but they didn't give you any left-hand inserts!

I have and use both, so I'm pretty familiar with their looks and their setup.  What you describe sure sounds like a right-hand (exterior) threading tool in a left-hand (interior) threading holder!

Lloyd


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 12, 2017, 19:55:15 pm
I figure, somebody could use this..

Best.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 13, 2017, 22:21:23 pm
I went back and had a look at the original invoice for the tools, and you can clearly see that the RH tool that I was sent is a Turning tool and not a threading tool (they are clearly different). ::)

I decided to do a quick test of the turret to see how well it would cut, so I turned a 19 mm rod down to 11.75 and then threaded it to M12 x 1.75.

Went very well, As I didn't have the stepper motor connected I did the tool changes "Fred Flinstone Style" by hand and pressed cycle start to continue on after the tool change was done.

On the battery front, I friend gave me four 18650's and a charger, so I now seriously have to look at how to squeeze that stuff into the turret.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 21, 2017, 14:11:55 pm
Another small update and video

In the video a complete G-code program was ran from the start to finish and happily Mach3 and the tool changer
agreed on which tools to use for each operation.
https://www.youtube.com/watch?v=04_8UEFjlZE (https://www.youtube.com/watch?v=04_8UEFjlZE)
Dave



Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 21, 2017, 22:02:09 pm
Another small update and video

In the video a complete G-code program was ran from the start to finish and happily Mach3 and the tool changer
agreed on which tools to use for each operation.
https://www.youtube.com/watch?v=04_8UEFjlZE (https://www.youtube.com/watch?v=04_8UEFjlZE)
Dave



I tried to look at it and got a message 'This video is unavailable'. ;)


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 22, 2017, 00:55:49 am
Hi Bubba try this https://www.youtube.com/watch?v=04_8UEFjlZE&t=16s (https://www.youtube.com/watch?v=04_8UEFjlZE&t=16s)
(I found that if i wasn't logged in It would not play for me either)
Dave


Title: Re: Automatic tool changer for the lathe
Post by: Bob La Londe on October 23, 2017, 16:03:04 pm
Google is getting to be more mercenary with YouTube.  They keep changing rules so their big contributors don't get paid, push ads even on videos that have ads turned off, and constantly seek to get users to buy a subscription to RedTube when using mobile services.  I will probably start using Vimeo for more of my videos or atleast mirroring them to Vimeo and Daily Motion. 


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 23, 2017, 17:25:11 pm
Sorry Dave. No Joy.. ;D


Title: Re: Automatic tool changer for the lathe
Post by: Garyhlucas on October 23, 2017, 18:00:42 pm
Bob,
You do know that redtube is a porn site?


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 23, 2017, 23:45:47 pm
HI Bubba
I went back and a look at the video, and fiddled with the settings, hopefully it'll work now (the first link I posted)
if not just type in "Lathe Auto Tool Changer 3" into youtube and see how you go.

What you see in the video is a G-code program running from start to finish with lots of tool-changes.

It took a while to get here, as part of the "goals" of the project were to have a battery operated wireless Bluetooth connected Auto tool changer That required little maintenance and was easy to set up (software wise).

This what I've got so-far, you have to add "three lines to the start script in Mach3",then  plug in the dongle (and pair) run.
start Mach3---> start Plugin----> program as normal.

The turret is autonomous, and can either listen to or command Mach3 and requires no changes to the way you program your lathe with the software you have already.
 
All you do then is to re-define your G53's as they will likely be different to mine.

I've also  looked at using OpenCV to monitor the tool changing and report chipped tools (you can see in the last video the "OpenCv" frame open and capturing the turret moves.

You wont be measuring tool wear, but detecting a complete tool-change or broken or chipped tools are a possibility.


Dave


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on October 24, 2017, 00:32:48 am
See the video. Yep, you got it working. I doubt I will be converting my manual lathe any time soon (Clausing 48" bed). But your posts should be great aid for someone who want to go that route.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on November 12, 2017, 12:56:45 pm
Another Update and some conclusions.

Overall it was a good project that offered plenty of challenges, but nothing “too” challenging.

As I “MacGyver'ed” it together “scrapheap” challenge style from bits and pieces on hand
It ended up a little too heavily built  for the application (16 mm plate instead of 12 mm)
and would suit a 10 x 40 or something similar.

Mechanically the tricky bits were:-
1.The Ratchet and Pawl.
2.The Tool Platen.

With the ratchet wheel, I had to make it twice, as the finish was a little off, and by the way the mill sounded something was loose. The Y axis was a little lose. So I couldn't trust the dimensions. And started again. The final one did show some “strata” type tool marks but in practice works well.

Everything went well with the pawl.

With the Tool Plattern, I had a power interruption for a couple of hours and had to reset the co-ordinates. There were some depth of cut differences, but I thought I would clean them up with a file later. This was a mistake as I should have done this on the mill while it was still indexed and saved a lot of time.

I also found that the walls of the tool holders were not straight, but had some draft at the bottom of the cut which meant that each and every tool slot had to be reworked on the shaper and then filed perpendicular to the floor of the slot.
I used a 3/8 end mill for this, but should have been ½ inch at least.

Originally I had the stepper motor and gearbox directly coupled to the turret drive shaft
But had to move it inboard some 30 mm to clear my X axis bearing mount. This involved adding some 1 to 1 gear's  and removing the inline coupling.

Interestingly I lost some high speed  acceleration  (about 20 %)  just by doing this (I had taken some benchmarks when programming the velocity and acceleration curves ) for the inline motor configuration.
I put this down to the now  radial load, canting  the gears a little and adding more friction
to the gear train.


Electrically:-

I'm using 3 18650 batteries (4000 ma)  to power the turret.
The idle current was 285 ma and the tool change current was 628 ma.
I did do a estimation the battery life  using fairly conservative figures and thought 720 tool changes  would be an upper limit.

I set out a test, to see how many tool changes I would get in real life, so I made a short Gcode program with 48 random tool changes that went for 11 minutes and ran this for 3 hours.
I felt a bit nervous about letting the batteries deplete too much and so set a limit on the discharge to 10.5 volts .
By the time  I got around to removing the batteries for recharging (about 10 minutes or so), they had recovered a bit as each cell measured 3.69 volts. The batteries did take the full 80 minutes to recharge.
Those batteries do pack a punch as the total tool changes per battery charge is 864.

I did have trouble with the lm298 driver on the shield as it provided less power to the motor
( I think it's the “on state resistance” perhaps it's a bit higher)  and so went back to the “off board driver” which gave me a reasonable tool change time of 5 seconds.

The turret is “plug'n play” either use it and run the plugin, or use your manual tool post  and don't run the plugin.

I've also accidentally “christened” the turret and tested the safety overload at the same time by running it into the chuck spinning at 600 rpm at full rapids. (Errant G28 in code and I should have set this to the tool change position G53 to be the same values) The tool holder was struck by the chuck jaw but swung out of the way. See picture of tool, there was some paint knocked off, other than that there was no damage.

What I had to do then was, reset the centre height (which is lost when the overload is activated) which took about 10 minutes.

edit spelling









 









Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on November 12, 2017, 16:17:10 pm
Dave,

What an excellent project and result, you should be proud of it, especially taking into account all the different disciplines required to complete.
Could you have use a timing belt to connect the stepper motor and gearbox ?
Could the batteries be charging in situ when the turret is not in use, or would wires to it spoil the job ?
Edit: Note to self(Eddy), you clown.


Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on November 12, 2017, 18:54:32 pm
Eddy,
If wires could be properly routed to the head and flexed as required, then there would be no need for batteries!  :D

Lloyd


Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on November 12, 2017, 18:57:27 pm
Good point  ;D  ;D  ;D

But wait a minute, what if the electronics required a totally ripple free DC supply  :D


Title: Re: Automatic tool changer for the lathe
Post by: Bob La Londe on November 12, 2017, 20:45:09 pm
Bob,
You do know that redtube is a porn site?

Nope, didn't know that.  Just know Google (who owns YouTube) keeps trying to force me to buy an enhanced YouTube experience.  Must have gotten the name wrong. 



Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on November 12, 2017, 21:46:27 pm
"....what if the electronics required a totally ripple free DC supply?"
--------------
'Tain't no such thing, Eddy, MOST ESPECIALLY from batteries, which possess a specific series resistance, and ALWAYS cause 'ripple' (load variations) with varying loads.

A properly filtered power supply with a large post-filtering capacitor posessing a low series resistance will beat a battery every time!

Lloyd


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on November 13, 2017, 05:03:59 am
Hi Eddy

Yes it's been a interesting  project  'and' on the whole I'm satisfied with the result, But far from content.

When I started out, the goal was to make a cordless\Bluetooth tool changer that was Plug'n Play
for example if you had a job in the lathe which requires changing to  the manual tool post (perhaps you need to do some deep boring)  then you would unbolt the turret install the manual tool post
and continue on without changing tool scripts or fiddling with mach3 at all.

With the batteries, I was figuring on 500 tool changes at the outset, and so to get 864 just means that
I've got plenty of power left to do something else.

What I propose to do is make another two (based on the lessons learned from this build) and flog them off on Ebay and if  They sell I will use the proceeds to build a Beagle Bone Powered version
with a video camera (maybe a Xbox connect) to run Opencv and some python Ai to add →

1. Home switch functionality
2. True Tool identity
3. Tool Change complete confirmation
4. Tool damage and misalignment
5. Collision Detection\electronic fencing 

I've already drawn up the turret to standard Steel\Fasteners dimensions.
I have some cold rolled 12mm and 16 mm plate.
I've ordered  two more housings which have even heavier bearings but are shorter in the snout.

The new ones will have Bi directional control meaning that the turret will select the shortest path for the next tool change.
As part of doing this requires using two pawl's and a (RC servo or a solenoid ) .
The by product of this is that the turret will be rigidly locked in position for both directions.

I did look at 4 axis positioning capability and with the addition of a disk brake, it would be possible
But not very practical, what you would really need is a high torque compact motor and drivers ect.
that fit in the same space, as the present kit, I did look at one compact atmega2560 board and a slew of micro style stepper drivers, and so miniaturisation is possible for the controller but not the stepper drivers as they don't provide the mode I'm using.

One  thing I'll have a look at is to use one of those “One battery for many tools” and charger from the local big box stores, as the battery has visual indication of charge  as well as low voltage cut-out
in this way I could off board the battery and electronics and free up space inside the turret. And as you can see in the cad file image, there's not much room and that's without the LM298 driver.

The tricky bit would be to machine a fitting to suit the battery.
But I  will look into this as the benefits would clearly outweigh time spent making the CB file in the first place.

Dave








 
 


Title: Re: Automatic tool changer for the lathe
Post by: Bob La Londe on November 13, 2017, 15:35:19 pm
Maybe this is over simplification, but why not setup so you can just add a tool post when you need to do that?  A lot of guys run a t-slot table on their cross slide for gang tooling. 


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on November 13, 2017, 23:15:46 pm
Hi Bob

Here is a shot of the top-slide from the rear, when I was repairing the the top-slide during the lathe build, I added
some extra spigot location holes for the manual tool post, although in practicality I probably wont use it.(no space)
What I have thought about is a rear gang tooling block or a rear mounted parting off tool.

I do like the idea of a rear parting tool for small lathes like this, and I think I will make one.

If you were setting up the lathe for production work, for similar parts, you could fine tune the tool arrangements in the turret and the gang tooling ect. But for me the parts would be one offs so one day I might be doing long thin turning and the next chucking work. 




Title: Re: Automatic tool changer for the lathe
Post by: dave benson on December 04, 2017, 12:56:53 pm
Another small update
I've been using the turret for a month now on a variety of jobs (including making more turrets rap rap style)
There are a couple of things that I've changed from the original turret specs.

1...Moved the mounting bolts to the outside of the unit this makes it faster to remove ( 1 minute), with the original it takes at least five minutes (you have to remove the top cover before removing the mounting screws).

2...Up-ratted the main bearing specs (there was no need to do this except the new heavier housings are cheaper to buy
and more readily available). I mainly did this to achieve less over hang from the cross slide, the snout is 40 mm shorter.

In the process I discovered the person that made the 4 jaw chuck that came with the lathe missed every dimmension
by some margin, the jaws  not only varied in height on each step,but were not ground flat (0.06 mm) difference between each side of the jaw  :o.

I've made two front bearing plates,Pawls, Ratchets and need to machine one more bearing housing.

I wouldn't characterise the The cast steel housings as hard, but "tough" as I eventually used three (6mm) cutters to do the job.

I haven't had to charge the batteries yet.

I've played around with the opencv libs and C++ for the beagle-bone  (industrial) and at this stage can't see any big issues in using the libs for what I want to do, but because you are dealing with the fixed set of methods in the library
and 900 Mhz, that if you  pre-process the images then tool detection and identification is good.

I'm also looking into the Raspberry Pi 3 but it's power consumption may be a little high for this purpose.
Of course the main thing I need is SOC that runs Opencv and can drive a stepper motor, that has a small foot print
and is easy on the power.

Dave
 




 


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on January 20, 2018, 05:47:45 am
Another update:

The new goal of the project, was to make another couple of turrets from  standard  size stock materials and fasteners, and to set up the software (Freecad -->Cambam -->Camotics) work flow so as to make them in a quick and efficient manner as possible with the equipment that I have.

I'm using CamBam 0.98 and Camotics, both of which have worked well together.
I'm using the latest  Freecad binaries of 0.17 13050, like they say on the website these versions are under heavy development so save often.

There's practically no documentation for these versions so if you want a relatively painless (Import/Export) experience and want to use the Assembly workbench's, then these are the way to go however you have to be fairly proficient in 3d parametric modelling to get to grips with these versions.   Although a little persistence is well rewarded.
 
Now I have two turret bodies ready to except the tool holding platterns.

As you know I MacGyver'ed  the first turret together (Scrap Heap Challenge style) over a few weekends from material I found fishing around in the scrap bin. (16 mm plate was a little overkill)

I'd already started machining the second Tool Holding Plattern a couple of weeks after getting the
first turret running, after making some making some improvements to the design, for example
adding a longer toe to the tool rests to support the tools more (see picture), however I found out by using the first turret almost daily for the last 3 months, that I was fixing a non-existing problem.

I did move the mounting holes to the outside of the turret to make it quicker to dismount.
The other thing I did was to move the overload mechanism to the front of the turret so that you could reset it without having to pop the top and one side off the turret. I've only had to reset  the overload  three times crashing into the chuck, (Ezilathe was adding a G28 and I hadn't set mach3 home position as I use G53's.)

I also changed the shape, so that I could affix tools to the periphery of the tool holder and changed the dimensions of the tool rests to accept half inch tools rather than the 12mm ones that I originally
had planned for (this does mean that you have to shim the tools to get the correct centre height) just like the original tool post. see pic 2

The first design took 37 hours of machining time, even though I was using the Troc mops and had
set the code for 10 mm tooling and .5 mm DOC and 200mm Feedrate (on a normal profile mop I use 100mm).
This seemed to work for a few hours, but eventually the spindle motor overheated (it was a hot day 38 deg C  outside, don't know what it was in the shop but a lot more I guess).

The other thing using the Troc mops generates huge files and the mill computer took noticeably
longer to respond. 470,000 lines of code.

So instead of machining away the “Islands” between the tool rests (which was most of the work) I made the tool rests separately and did some hand preparation of the material.

And now the job takes 6.5 hours of machining time, plus the hand prep I'm doing. Mostly baby sitting the mechanical hacksaw. I could do this with the 9 inch grinder to make it a lot faster (but I like my neighbours.)

Dave






 


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on February 08, 2018, 23:38:30 pm
Another small Update
Well I finally got the second turret Backing plate and tool rests made using this process:

1. mark out the bar stock with an endlmill and drill and counterbore the bolt hole recesses.
2. Cut out the shapes roughly to size.
3. Use a jig to do each tool rest separately. Full Depth cut shrinking toolpaths

This method worked reasonably well, although I made a mistake by machining a chamfer too early in the process and I will change this for the third turret. This was only problematic because I forgot to square one of the pieces of barstock before starting out.

This method is by far the fastest, but required  more setups and indicating back in so today I'll try a different method
where I'll cut the barstock a bit wider and cut three rests out at once, this will take longer than the grinding method
(to cut the pieces) but will reduce the handling time. and potential errors due to misalignment between setups.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on February 09, 2018, 08:30:04 am
Dave,

You must have a nice range of machinery now.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on February 09, 2018, 15:28:45 pm
Hi Eddy

Don't know really how nice they are, the mill is home made from a Taylor and Hobs Dimensional
Co-ordinate Measuring machine, the Spindle is a all cast iron Lathe Head (Heavy), the ball screws are NSK and Lead shine drivers. Crappy non machinist vice, although I did modify it  with an Anti  lift Toe Plate on the moveable jaw it  still lifts almost consistently 0.2 mm
Because I was going to make interchangeable parts (the tool rests) I needed to know just how accurate the whole process was, so I measured everything as I went along.

With the heavier loads placed upon it, by my doing these turrets, I've come to grips with it's true capacity and find the Z Axis A little wanting in the rigidity Dept and need to do something about it like heavier capacity slides and a ClearPath servo for a spindle drive.

What I was really interested in, was  this problem -> The tool rests have a 3mm roll pin to position them on the backing plate and a M6 SHCS to lock them down. The M6 measures 5.85 and I drilled a clearance hole to 6 mm and so a clearance around the screw between the thread and the side wall of 0.075 mm.

I took some measurements “of holes drilled to full depth” on both top and bottom of  a test  plate but these were somewhat inconsistent, as if you saw the “Bull's Eye Plot” the holes were grouped mostly in the positive direction towards the operator,  we are  talking about  Drill positioning error not Milling error which was different.

The first thing I did  was checked the gib's and reset the spindle preload  and the tram was out a little too, I also changed the mops a little by adding a spot facing  milling op before the spot drilling op.

The other thing is that I'm using a 3 Jaw chuck which has it's own run-out and so I had to indicate each tool in (by undoing the key and rotating the tool 30 Deg  and doing up again and keying  the chuck in the right order) sometimes I 'd luck out and get it only after a few times, other times it took many attempts. 

After a lot of fiddling and quite a few dud parts, it turned out well in the end.
 
One other thing is that  3 mm HSS drill's aren’t very rigid, so   I used a new cobalt drill, as these
have a thicker core diameter compared to a standard HSS drill and are stiffer.

There's always going to be a bit of error in any machine,system or process, and if you know what that error “is” and then if you design your part “with that in mind” you can save yourself a lot heartache.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on February 21, 2018, 23:05:00 pm
Another progress update.

Well after what seems an eternity, I've managed to get both of the tool holding plates complete, as far as the cnc'ing goes, there is still some still some hand finishing and a chamfer on one plate which I'll do on the lathe.

The tool rests in the upper of the picture are the Failures, so to get 12 good ones I had to make 20 all up.

Three of  four on the far left were on size and would have been ok to use, but I thought I would add the recessed pocket to them, for style reasons only (should have given myself some Gansta Slaps at this point) as I didn't have enough room to put the M5 gib adjustment screws in afterwards.

The other four (the first one's I made) were  under size and had a poor finish, after this  I checked the mill over properly and trammed it in, and completely changed the method's used to to make them and opened up the tool recess enough to use ½ inch tooling which I do have some of.

NMBR 2 and NMBR 3 turrets differ slightly in the way tool plattern's bolt up as I realised that I could eliminate six extra M6's and the associated machining ops by using the tool rest securing bolts to fix the tool plattern to the  spindle shaft.

NMBR three's PCD is 84 mm the same as some chucks so that with an adapter plate you could use a chuck and use the turret as a (positioning only) 4 Axis.
Both new turrets will have an Disk Brake to enable you to do this.


What I have to do now is mostly lathe work, and because I decided that the overload mechanism securing bolt should be moved from inside the turret body to the outside (to make it easy to reset)
and so now it has to be left hand thread.

 I've ordered a M14 LH thread tap and die and intend to Get a couple of M16 x 1.5 RH Thread bolts and machine them down to suit the M14, that way  I can use still a standard 16 mm  socket with them.

On the programming side I've successfully set up cross compiling for both a Beagle Bone Black
and a Raspberry Pi with VS 20017, I've also setup a project that just uses an Arduino and uses the host computer to run OpenCV and will test out each option (they all have their good and bad points) when I've finally got the turrets operating.

I've got some time now so I'm of to the shed to bore the clearance hole for the M14 and drill the backing plate to accommodate tool plattern.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 01, 2018, 04:30:29 am
Face Plates shafts, and Ratchet wheels Finished.
Just waiting on tap and Die, just need to add the M6 Gib adjusters and some extra holes on the periphery for
the tooling that bolts on to the side of the tool holders (for boring bars and spotting drills).

Dave


Title: Re: Automatic tool changer for the lathe
Post by: Dragonfly on March 01, 2018, 07:26:20 am
Look very solid.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 01, 2018, 23:20:04 pm
Yes they are overbuilt by some margin (which is poor engineering) really.

I had to calculate the the force required to keep the overload securing bolt tight enough for normal
operation during  turning, but would release during an overload situation like running it into the chuck.

I calculated the cutting force to be no more than 200 Newtons even with some extra safety margin.
These bearings (a pair of 68 mm OD  Angular Contact) have a Static Load Rating  at 30900 Newtons each!
The thing is, these bearings are cheaper to buy as they are more popular, and so many more are manufactured than the correct sized ones for this job.

The spindles are Cro/Molly and the ratchet wheels are 1045 medium carbon steel.
The only upside (with being so heavily built) is that the surface finish and my ability to get much better sizing (first time round) of the of the lathe has greatly improved on both counts as compared to the original manual tool-post.

I greatly under-estimated the battery life as well, as after watching BigClive on youtube speaking
about the real as opposed to actual battery capacity of the Chinese L/ion batteries, I rated mine at 2ah they have 4ah printed on them.

Last Saturday I pulled them out (for the first time since installing them in the turret) and placed them in my fancy battery charger which gives you a blow by blow description of what's it's doing and the battery voltage's were 3.75,3.75 and 3.73 volts respectively.

This to some degree, is because if I have a simple job of turning to a diameter and no tool changes
I don't even turn the turret on and just select the tool required by rotating the turret by hand like a using a quick  change tool post.

After watching the guy on ExplainingComputers.com I was leaning towards using a Raspberry Pi
instead of the BBB because of the built in hardware 264 Video decoders, but the power requirements 2.5 amps seemed a little high for the battery capacity I thought I had, but now I think this might be Ok.

Dave 


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 06, 2018, 12:37:52 pm
Another small update
I've finished the bearing housings and am just waiting on the tap to finish the spindles.
Here's a pic of the comparison between the original tool post and the new turrets.

The next and last this to do is adapt a disk brake to the spindles before adding the electronics.

I did order a Chinese one, however it may be a little big and so I might have to reverse engineer it and make a smaller one based on it's design. The Irony of this hasn't passed unnoticed ::).
 
I've looked at some Li ion battery packs that have built in battery management, just have to find one that is the right dimensions to fit.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: Bob La Londe on March 06, 2018, 16:16:58 pm
I am sure you have thought of this (and I think I read that you did to).  Why not use a cordless drill battery that has a manual charge indicator on the front like my Milwaukee drill batteries?  Then use a voltage regulator to get a lower voltage.  Start the machine, check the battery, swap to the one on the charger if its low.  They are modestly expensive, but very good batteries.  If you want higher voltage string two together in series with two locking cradles.  Maybe a pair of 20s or 24 regulated down to 36 for a nice solid higher torque modest speed stepper application.  

I have 18s, but I would go higher so you can maintain constant voltage for longer by using a regulator.  36V is a decent voltage for a small stepper controller and stepper.  Its not like the tool changer has to be fast.  Gear it down, be modestly slow, and rock solid for position plus or minus half a microstep. With that approach you might be able to run even lower voltage.

Sorry if you have already thought of all of this.  I admit I have not read the whole thread.  

I still question the wireless approach, but I am anxious and curious to see it work.  


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 07, 2018, 04:21:55 am
Hi Bob

With the wireless link, I've been using the original turret to machine the others (and other things) for 3 months now, and the wireless link has worked faultlessly, mainly because of my industry experiences it's designed to fail safe. That's why I've never mentioned it as there was nothing to report.

I did look at the power tool battery pack idea and was very keen on this too,and as you rightly pointed out it has some great advantages and appealed a lot to me.

For example I could remote the battery management electronics and save space which is tight inside the turret and use off the shelf proven and robust components rather than something that I've cobbled together.

The “fly in the ointment”  here was the actual battery connection to the turret which would have to 
keep coolant and chips out of the interface between the battery and the  connection. I think that over time this would be a point of failure.
   
 Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 29, 2018, 01:08:02 am
Another small Update.
I've managed to get both new turrets finished up to this stage where they have run connected to the computer. So all that's left to do, is fabricate a Floating disk calliper for each, and then machine the top and rear covers which have some features that may prove interesting to machine, so I'll leave these to the very last.

The solenoid's for the brake activation have arrived, so I've started to cad them up and hope to have a working version late next week. (still waiting on the sensors for position and brake activation)

I've had jump through some hoops to get the Main Bearing Housings machined, as the fixing of the Z axis to the column, was found wanting (rigidity wise) under heavy loading, so I've ordered and received these Linear rails HGM25's the heavily pre-loaded types used for Z axis's (you should only use these with ground surfaces) which I have on the column.

So as soon as the Ball-nut fixing block arrives, I'll install them.
The only thing to do then, is perhaps change the spindle shaft to except standard tooling at a later date.

I've found the most time consuming thing is the upkeep of the drawing files to reflect what changes I've made in the shop, there's well over 60 Freecad/CamBam/Camotics/Visual Studio/Atmel Studio files as well as a slew of interchange files(.dxf's and .step) and it's nearly a full time job just  to keep on top of them.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on March 29, 2018, 01:40:35 am
Yeah... Keeping the docs' is almost a bigger job than making the parts.

I'm about to embark on two new projects for the shop... in another thread.  I don't want to hijack this one.

Lloyd


Title: Re: Automatic tool changer for the lathe
Post by: Garyhlucas on March 29, 2018, 18:44:53 pm
Our products have about 800 parts sourced from about 60 vendors for each job. Our SolidWorks library has about 4000 parts currently. We use a program called AllOrders that is linked to SolidWorks by our part number and a custom Excel macro. Export the SolidWorks BOM. Import to Excel and export the macro results whichs roll up all material lengths and quantities and import to AllOrders. Print POs for the materials, Picklists for inventory, Workorders for the shop, Packing List, and get a very accurate cost including labor for the whole job!


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 30, 2018, 02:39:40 am
Hi Garry

In 1982 I was the production clerk at RipCurl (the wetsuit people) where we instituted a similar scheme using
A Diablo Mini and several Osbourne portable computers and  (with the front cover which was the keyboard) clipped on, they very much resembled a sewing machine.

So I could do something similar, but the time to upkeep the "RipCurl System" required a full time position and was one of the busiest times of my life, and being a one man band,  doing this right now is not high on the priority list.

If I were to make the turrets in quantity, I would farm some of the 2 D work out  to a water-jet cutter and assemble the turrets in house were I could finish machine the parts and do the final assembly.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on April 12, 2018, 14:17:33 pm
Another small update.

Well the Ballnut mounting block finally came yesterday, so I'll install the new Z axis rails and slides
over the week end and am looking forward to seeing it run.

In the meantime, I scoured the internet and my engineering design books for a suitable design that would meet my requirements, but no joy as they either wouldn't scale or had too many moving parts.
So I broke out the drawing pad and doodled for a couple of nights trying to find something that would be simple and reliable, but had to be a floating design (self adjusting).

I narrowed it down to a couple of likely candidates and cadded up the best prospect.

What I needed was a negated brake (the solenoid when energised released the brake) which only happened when the turret was changing tools so as to save power.
 
I wanted it to be simple and this mechanism has three moving parts that move only 0.5 mm for the pads and 3 mm for the actuator.

The first pic is of the initial mock up in CB.
The second pic is the CB geometry imported into Freecad  and turned into a 3D model.
The third pic is the calliper bodies and a substitute rotor showing the pockets for the pads.

I've got some time tomorrow to finish machining the bodies and hopefully get the pads and actuator done.
I've already programmed the new parking manoeuvre and added a two stage variable power
method for the brake. (separate energising and holding stages) again to save power.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on May 24, 2018, 04:32:20 am
Another Update on the progress so far.

Well, I machined up the first set of  Calliper bodies using the slope property in the profile mop. (17.32 deg)  with  a 3 mm cutter and  0.1 mm steps.
I also left a 0.25 mm clearance on each end of the pocket so that the pad would float freely.
(this would come back to bite me later)

I then cut out the Brake pads, which I found very fiddly and hard to set up in my present vice,
and  I new I had to order a  5 in machinist’s vice to get any form of repeatability in my work.

I then assembled the calliper and tested it in the bench vice with a dummy rotor.
With bright led torch and a magnifying glass I actuated the mechanism with a pair of pliers.
And everything looked good, the pads opened and closed, but worryingly needed more force than I expected to operate.

The second problem arose when I rotated the rotor, there seemed to be a bit of backlash, and on investigation found that the pads were firmly attached to the rotor but moving in the pockets (with that extra clearance I gave them).

To address the first problem I machined up a new set with the minimum wedge angle the geometry would allow (to get the most mechanical advantage) and also took the clearance in the pockets down to 0.1 mm).

Ultimately this was a fail, cleaning up the pockets did reduce the lash to a very small level, but the force required to operate it 6 kilogram region and as  I'm committed to using as lest power as possible so I had to come up with another solution that only required a 3 kg force solenoid.

See next post
Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on May 24, 2018, 04:39:12 am
continued...
I could see now, that I need some force multiplication if I was going to use the 3kg solenoid.
On next attempt, I used a button Actuator which braked on the periphery of the rotor.
The picture shows the button “Centre Shaft” that the brake material would sit in.
To do this, I had to semi manual program an R70 radius in the ZX plane.
This went well. Pic 1

Next I made a capstan that fitted to the button housing and provided the necessary torque to activate the brake. Due to the space constraints I could only get 3 to 1 multiplication and I had to make quite a few of these to get it to operate smoothly (originally I  used a bush in the capstan but had to replace it with a roller bearing, which made all the difference).

This turned out to be a mini project all on it's own!


I then tested this out (ran it in one of the turrets) but  disappointingly it didn't have enough braking capacity, which meant that I'd have to install a heavier spring in the button but I wasn't sure how much extra torque there was left to do this.

So I conducted a little experiment and took the brake out and sat it on the bench, then placed a small plastic jug graduated in ml and filled it with water until the  spring popped. I did this a few times to get an average.

It turned out the force was 25 newton, the same as the solenoid and so with capstan multiplying the force 3 to 1,  I really could increase the spring pressure but  for various reasons I didn't like the idea.

So  I set that button aside (I'd made a couple) and ordered a 5kg solenoid  for it.

Over the next week or so I read some engineering and Mechanisms books and haunted the web to see what other people had done with braking mechanisms.

Then it dawned on me that a braking mechanism requires a fairly high force to operate that's the nature of the device, I now realised that I needed a Indexing Mechanism instead as they don't require anywhere near the same force as a brake to operate.
So was there another way to achieve what I wanted with the components I had already made.

It turned out there was, I modified the Disk Rotor by cutting 120 (3mm scallops) out of the   periphery.

I then installed some drill rod in the shaft of the button (this engages with the scallops) so I didn't have to make any new components only modify the ones I already had.

This finally did the trick I could now use the 3 kg solenoid  and a comparatively small spring to get the job done. Pic 2

Dave 


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on June 05, 2018, 02:37:06 am
Another  progress update....
Once I got the Design of the Indexer sorted out (many attempts with  different  geometry and materials)                  I then set out, to test it out!

I wanted to know these things:

How long would the battery's last ?

After many consecutive tool changes, would the Solenoid Duty Cycle be exceeded ?

Would the Capstan Cable hold up?

What would happen if the Indexer failed ?    Software wise.

What things were likely to fail in the indexer, and have some limited self diagnosis and reporting of the error.

To make the tests I made up a Gcode program consisting of only tool changes,it was supposed to be 100 but I stuffed up the cut and pasting and only had 96 , which I only found out during the course of the tests.


I added a couple of radio buttons Auto-recovery and Manual recovery.

What happens in manual mode, is the turret will signal a tool change abort (and hi-light's the tool number) in purple:
 For safety you now have to toggle the “Restart After Tool Change” button which will turn orange and indicate “No Restart after Tool Change” to Mach3
You now have access to the tool change buttons, and if you press the hi-lighted tool number an      tool change re-attempt will occur.

If  the  re-attempt is successful and a tool change begins or is in progress, then toggle the “No Restart after Tool Change” button and Mach3 will continue on executing the Gcode from where it left off.

Auto-recovery Mode
If the Auto-recovery radio button is checked:
If the turret senses a Indexer failure It will first assume that the duty cycle of the solenoid is exceeded, and do a re-attempt every 10 seconds until successful or 10 attempts have elapsed.
It will then do a  solenoid activation check  and if this passes, reports a cable failure\Capstan securing bolt lose error, or  else it will report a solenoid failure.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on June 05, 2018, 02:39:53 am
I started the tests without the battery's as I discovered that they need to be topped up and so used the
bench power supply.

For the first test I set Mach3 running and did 1064 consecutive tool changes keeping an eye on the solenoid temp and it barley got over the ambient temp which was (15 Celsius)  and the cable had held up fine so far.
I took some current draw measurements, and on average (using a two stage modulated signal) for the solenoid, the draw was an extra 250ma to 300ma (this jumped around a bit as I measured it with a multimeter which was a poor choice ) while the tool selection was in progress and at stand still the current draw was obviously the same as before.

So far the results were encouraging, but I was left a few questions:

I hadn't tested the solenoid in a high ambient temp environment, so if I heated up the solenoid 
(with the other half's hair dryer)  could I saturate the solenoid heat sink, and would it fail, and in what way, and how would the turret respond to this.

I set the turret off for another 1000 consecutive tool changes and harassed the solenoid with the hair dryer and got it too hot to touch for long but nothing happened and Mach3 finished and rewound.

I then did what I should have at the start, and calculated the rise in temperature above the ambient that the current I was putting through it would cause, turns out that the energising current would cause an 8 Deg C rise but this only lasts milliseconds and the holding current would cause a temperature rise of 3 Deg C.

So even though it seems to be  very unlikely that the solenoid would ever fail due to heat stress, I coded for this event anyway by letting the turret re-attempt a tool change every 10 seconds for 10 times then giving up and reporting a unrecoverable error.

I've also added a Homing Function that works by using a fast homing method (if the tooling is already indexed) and, if this sequence fails (because the tooling wasn’t Indexed and was at some random angle), a slower but more comprehensive (auto backlash compensation re-calculated) method is used.

So in short the battery life, which still has to be checked more thoroughly (so from the re-calculated value going on the measured current) I estimated that it should be around 650. and will test this as soon as I work out where to put them (the batteries) in the turret.

The Indexer (and thus the turret)  has an 100 % Duty Cycle, so continuous running is assured.
The Turret can change 900 tools an hour Indefinitely and has on occasion (last Sunday) ran 3600 in a row during the bench  testing.(with the bench power supply)

The indexer cable (which is synthetic not ferrous)  has lasted, north of 35,000 tool changes so far and shows no sign or wear.

So now I think I'm going to call the Indexer Done and the basic form of the turret (dimension and material wise) is settled.

What I intend to do now is make an Indexer for the other turret, to mostly check and clean up the
 Cad and Cam files (I had changed some dims) while actually making the Indexer at the machine's.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on June 05, 2018, 12:38:21 pm
I'm impressed. Nice work Dave.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on June 06, 2018, 15:24:44 pm
Hi Bubba

Well I'm not counting my chickens just yet, I think I'm over the Hump and most of the difficult stuff is done.
I still have to Make the Top Case which has to have a water tight seal and an access port to change the batteries.
Also a Rear end case with a portion removed and a piece of lexan inserted to allow the bluetooth module to function.
Because I used up some precious space inside the turret with the Indexer solenoid I had to order some small format
versions of the micro-controller, which are only 50 mm x 38 mm.

I made the other indexer base today, and while I was at it I thought I may as well make the other 11 as well, which from flat bar stock was a nice straight forward job.
Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 13, 2018, 05:29:06 am
Another small update....
Both turrets are at the same level of completeness (ready for their rear and top covers).
The second turret has clocked up a little under 9000 tool changes.

I did have to make a change to the design and fit a 4mm SHCS to the Stepper Motor to Indexer collar instead of the grub screws (Double Grubbed) to stop them coming loose. I would have liked to put another grub screw in the collar, but the stepper motor gearbox shaft has a Flat milled on it and there was no practical place to put one, anyway because the Allen Key for the SHCS is is so much larger you can tighten it up without fear of stripping out the grub socket.
This worked well and has seen many thousands of tool changes now, and has held fast.

Along with the indexer came some software enhancements.

The turrets can not be presented to the work piece  in an non-indexed state (Always synchronised with the present Mach3 running gcode).

 And checks are done for Miss Indexing (maybe you used the FEED HOLD or STOP buttons in Mach3, released the indexer and turned the turret around by hand in the middle of a job to inspect a tool and forget to set it in it's tool position or perhaps half way between tool stations. This doesn't matter any more as they Auto Index. See video at the 4 minute mark.
 www.youtube.com/watch?v=BZLU4gCf-UY&t=410s (http://www.youtube.com/watch?v=BZLU4gCf-UY&t=410s)

Dave


Title: Re: Automatic tool changer for the lathe
Post by: Bob La Londe on July 13, 2018, 18:32:13 pm
Nice.  Nice testing too. 


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on July 13, 2018, 21:52:33 pm
It look god on picture but couldn't see the video, it keeps buffering forever for some strange reason.


Title: Re: Automatic tool changer for the lathe
Post by: dh42 on July 13, 2018, 22:05:33 pm
Yes, same for me, the video must be 9:26 min long, but it stall at 6:48

To see the first part from 0:00 to 6:48, move the time slider to the leftmost position.

Nice job Dave  ;D

++
David


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on July 14, 2018, 01:25:52 am
Thanks David, your suggestion works. Nice work you did with the changer Dave. Now you need heavy production workload.. ;) ;D


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 14, 2018, 13:51:09 pm
Guy's
I don't what I did differently with this video that I'd done with the others!.
I'll try and upload it again when I get some time.

Nah, they will never see production work Bubba, when I was searching around for idea's after the brake Idea failed (because  I would have to had too large a solenoid to make it work).

I went over to a friends engineering works and we spent some time looking at his Indexing and universal Dividing Heads  (some of them fit their Cincinnati Number 5) and some small 12 inch one's.
It was very interesting, as there was some different methods used to index, and a lot of very fine machining and grinding.

One thing for sure, was that I wasn't  going to achieve that level of precision with my machines
or my ability trying to make a true Indexer.

So while I still call the Indexer “The Indexer” I had to modify the scallop features from being a semi-circle to a modified sine wave and modify the parking routine with a small rocking motion
which Latches and Unlatches the Indexer.  This works so well that, once latched the solenoid alone can not unlatch the mechanism without the motor doing it's little dance.

The only time so far that I've used the turret in anything like a production manner was when making the indexer bases in the above pic at the same time I ran the lathe making the Indexer bases 10 off which consisted off 4 tool changes Right hand turning tool to machine 25.4 down to 25 for 300 mm and then the Parting tool used to grove the material down to 10 mm dia at each indexer body length and then left and right hand chamfers on the ends of each cylinder.

The lathe ran through and finished unattended while I was baby sitting the mill making the indexer bases because  I had to stand at the mill with an extra air gun and help evacuate the chips during the deep spiral milling operations.

Of course at this stage the bodies were only half finished and had to be removed from the lathe and cut at the parting lines into cylinders which, were then faced each end and bored and stepped for the spring relief and the bush.

So this meant that in the 2 hours it took to machine the 10 indexer bases, the lathe had  finished the 10 indexer bodies to the half way stage at the same time by itself  (45 minutes)  I didn't even look at it until I finished the indexer bases and while not fantastic, in this case it was a definite help.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 29, 2018, 05:27:42 am
Another small update.

Well I bought the material for the ten turrets, and this turned out to be problem as I had gone through the bill of materials and realised that I could use one dimension of material (110 X 12 mm X 6m) instead of the two widths (130 X 12mm X 6m and 100mm X 12mm X 6m) I had originally used,  and so modified my drawing to suit, and last week went to get the material, only to be told that they have lengths as 110 mm X 10 mm X 6M, and that in the dimensions that I wanted , this would be a special order, so I had to re-edit the drawings again for the umpteenth time for 130mm X 12 MM X 6m lengths. 
The only good to come out of this was, That I learned some new things about setting up the Freecad Drawing properly and using the appropriate constraints for the task at hand. Once I had the correct type of constraints in place (had to edit every sketch) changing the material dimensions was very easy, and the 3D model re-adjusted itself  (Bolt Hole Positions,features ect.) moved to the appropriate positions.

So what I had now to do was, cut the turret bodies from the 12  (1 m) lengths  I'd gotten from the steel supplier. Each end had to cleaned up, as they were cut with a shear (as they were too wide to go into the cold cutting saw they had) .

I calculated the length of the cut to be 20.8 metres by 12 mm deep and didn't want to subject my 6 inch or 9 inch grinder to that much work.
Didn't really want to use the Abrasive chop saw either as the material was awkward to position.
 
So I marked the cuts out on the first length of material, got the Abrasive cut off saw out, set up the material and pulled the trigger, the saw started up made a horrendous noise and let the smoke out in a big way.
This only left me with the old  mechanical hacksaw which I'd used maybe two or three times in the last 25 years (mainly because it didn't cut particularly straight or fast) but was good for the times when you needed to cut stock 100 or 150 mm in diameter.

What I wanted to do was, cut the ten turret bases fairly close to size and square the whole lot of  them up in the shaper at once, so ideally they should be two or three mm over size but fairly consistent.
In the first pic you can see that not only, was the cut  not square, it' was tapered some as well.

I had to spend three or four hours making a new Crank drive pin and replace 3 of the four bushings
in the pulley drive system to get the cut in the second picture.
Of course it's still glacially slow though.
What I have to do now is continue on with the rest of the  bases and then fixture them somehow, so that I can do them in as few set-ups  on the shaper to square them up.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 29, 2018, 06:57:30 am
Continuing on, as far as the coding goes, I thought that I'd finished most of the logic and could tidy up the code and make an installer ect, then I saw this video https://www.youtube.com/watch?v=3NN4NxFI2SY that shows a Mach3 screen set that he wrote for a industrial retrofit of a turret lathe with 6 tool positions, but each tool position could have three tools, this meant that the turret tool slots had to be re-mapped or Aliased for each tool in that particular slot.

With these turrets, I did add some holes around the periphery to bolt tooling on, but was thinking that you would replace one tool with another rather than having both at once.

And  seeing that it was possible to bolt two tools in the same tool slot, I made an Aliasing table so that you can re-map the tool numbers as you wish.

This means that for example if you have remapped tool position  1 as  88  then called tool 1 in the Gcode then the turret would move to tool position 1 and apply the offset for  tool 1 from the Mach3 tool table and if you call tool 88 then the turret will still move to tool position 1 but apply the tool offset for tool 88 effectively giving you more tools in the turret.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: Garyhlucas on July 29, 2018, 17:20:34 pm
Dave,
I don’t have room for a horizontal bandsaw. However I have variable speed Milwaukee Portaband and a Swag Offroad table for it. A Portaband is great for metal cutting. I get custom very coarse 6 tpi blades made for cutting aluminum. Milwaukee has the highest blade speed in a portable along with constant torque varispeed for hard metals.

The secret to cutting dead straight with a Portaband is to pretend you are a lefty and on the other side with your left hand on the trigger. The saw is closer to you and can hold the weight of the saw off the blade with your right hand. I’ve done beautiful miter cuts on 6” channel this way. They had to be nice they were installed as a valance in my bosses kitchen!


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 30, 2018, 00:14:11 am
Garry
Quote
pretend you are a lefty
Don't have to...

I would like one, But I couldn't justify the cost for this project, the cost of the 12 meters of steel was about $220 dollars
cut into 1 meter lengths with a shear, so about 5 mm on each end of each 1 m length has to be cutoff as it's deformed a bit.

I inquired about cutting it up, and the cost of the cutting was more than the cost of the steel. $230 and because of the shear cut ends, I could not get it cut to size which would have defeated the purpose, as I would have to clean up each end of the cut anyway.

I went down to our local Tool Store and looked at a "Import" Bandsaw, which was $400 and and could be used as a Horizontal and vertical saw, I liked it a lot but on reading the manual, it's cut width was 30 mm too small.

So at this stage I'll have to go with what I've got, but if these sell and I've got orders for another 10 then it would be
the way to go, although the Bandsaw to cut that width of steel was $650, you got much better machine for that price.

Anyway What I've been doing is setup the Hacksaw and running it, and while it's running, square up the material on the shaper which lets me keep an eye on the saw as it has no auto shutoff yet.

I really wanted to cut the 10 Base plates at once then set them up in the shaper in a jig and square them up 10 at a time, but I have to run the saw so squaring them up at the same time makes sense as I'm doing something while waiting for the saw to finish which takes about 15 minutes a cut.

Dave




Title: Re: Automatic tool changer for the lathe
Post by: Bubba on July 30, 2018, 18:21:50 pm
I don’t have room for a horizontal bandsaw. However I have variable speed Milwaukee Portaband..
*************************
That what I did, needed cut off saw and didn't want to spend money on something that I seldom use. Having Milwaukee Portaband, I made an arm for it adopted cheap Chinese vise and it work just fine. Surprisingly, the cuts are pretty square..


Title: Re: Automatic tool changer for the lathe
Post by: dh42 on July 30, 2018, 18:46:26 pm
Hello

For my part, I have a small FEMI; it's expensive (~350€), but I do not regret it (it's definitely better than the hand saw !  ;D)

(http://i27.servimg.com/u/f27/14/07/22/66/0312.jpg)

(http://i27.servimg.com/u/f27/14/07/22/66/117.jpg)

(http://i27.servimg.com/u/f27/14/07/22/66/218.jpg)

++
David


Title: Re: Automatic tool changer for the lathe
Post by: Garyhlucas on July 30, 2018, 23:49:26 pm
That's not a saw.  This is a SAW!  Marvel Model 8 tilting head with 18" x 18" throat.  We cut lots of 12-3/4" diameter pipe and we have some 16" in the shop as well.  You can use the T-slots to clamp a flat slab on the table and it will power feed the blade through it.


Title: Re: Automatic tool changer for the lathe
Post by: Bubba on July 31, 2018, 00:41:06 am
Yeah, I even changed blades in them (pain in the ass) 'sliver special special'. But, when the guides are set right and good blade in it, you can cut pretty much 'dead on' dimension. I think what Dave need is something like portaband it does come with power feed , it is called gravity  ;D ;D


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 31, 2018, 03:04:25 am
That's a good idea, I'll keep that in mind Bubba, looks pretty sturdy to me. You've planted an idea here and I'll keep an eye out on the auction sites and if I can find one cheap enough.

 David, I think your saw looks similar in size to the saw I looked at (the $650 one) although that one looks  better made. Wish I had your lathe.

I see  both of you have your stock orientated vertically, this was my want too, but this little  saw won't accommodate this, so I had no choice but to lay the stock at an angle. About 60 deg.
Which gives about 40 mm of teeth in the cut.
 
This is not ideal as due to the minimalistic design of the saw, the crank angle relative to blade holder changes from the bottom to the top of the cut, in practice what this means is that at the start of the cut you need a little more pressure on the blade to make it cut properly ( I made a collar that fits onto the front of the blade handle) on the other hand at the bottom of the cut the blade dig in more and some weight would have to be removed.
 
Too try to remedy this, I attached a Parker air cylinder (40mm dia) and a flow control with integrated check valve to the hacksaw arm and filled it with compressor oil, it took ages to bleed properly.
I added some weight to the hacksaw arm so now I can get reasonable regulation of the cut by starting the cut and then adjusting the control valve and listening to the sound of the cut.

The only problem is that the system bleeds down at about 2/3 of the cut depth, so at about half way through the cut, I stop the saw and re-prime the cylinder by lifting it out of the cut, shutting off the valve and setting the blade down into the cut again  and adjusting the valve again.

I have to say, that I did the first three turrets mostly with a 6 inch grinder and lots of those ultra thin cuttings disks, which made short work of the job ( I guessing about twice as fast).

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dh42 on July 31, 2018, 04:25:33 am
Hello

Quote
David, I think your saw looks similar in size to the saw I looked at (the $650 one) although that one looks  better made

It's an Italian product ; Mine is from ~ year 2000 ... model 105 (weight 17 kg) = actual 780XL.

This product still exist: 105, 120 and 150mm (Ø maxi for a round stock) with manual or automatic feed.

http://www.femi.it/en/

My automatic feed system  ;D  ;D

(http://i87.servimg.com/u/f87/14/07/22/66/scie_a10.jpg)

++
David


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on July 31, 2018, 08:55:17 am
I call that good use of available resources ;D.


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on August 09, 2018, 13:56:03 pm
Another small update.
I have finally settled on a design for the Base Plates, and have cut and shaped the plates to size.
I have decided to standardise the CB turret files by including the stl of the part in every file.
I had to make a vice stop and orientate the vice along the milling table to get the Y Axis clearance.
I used a 16 mm endmill for the end features, which went well and saved a lot of time.

I also ran a air line to the mill and made a mounting for it and pointed it at the endmill, this worked better than I expected in removing the chips from the slots, even at the deepest part of the cut. The only annoyance was that the compressor cycled quite a bit (every 4 or 5 minutes) which seems a prodigious waste of energy.

I'm thinking that there must be a better way, perhaps a small 24 volt motor connected to a bellows style pump.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on August 20, 2018, 13:00:52 pm
HI All
Well this last week, I was supposed to have finished the 10 Base plates and started the side plates.

On the third plate into the job, the mill computer expired (hard Drive)  and upon opening it up and seeing the build date
on the cd rom (2001) I though I'd better retire it and get a new computer, then on a whim, I decided to use the NVEM controller I had sitting around (I'd kept it for another project) and it took a full week to rewire the mill and get the controller setup with the correct version of Mach3 and to operate properly.

I had to fiddle with it endlessly and the only thing I failed to get going  was the joystick, (turns out it wasn't going to work) so I've ordered a encoder wheel with which to make a pendant, as well as a base plate that fits onto the spindle with a er32 collet holder.

Dave



Title: Re: Automatic tool changer for the lathe
Post by: dave benson on August 26, 2018, 14:23:10 pm
Another small update

Thinking about the compressor problem (it was cycling to much) and besides being noisy, was a huge waste of energy for such a simple task, I went about re-purposing an old 12 volt mini compressor by machining off the motor and replacing the bottom end bushing with two 22x8x7
roller bearings and mounting it to the spindle.

I didn't know if it would work, and was concerned about the heat build up with continuous running
or if it would pump out enough air volume  at a reasonable pressure  to remove the chips from the bottom of the 12 mm deep slots in the turret base plates.

And after a couple of hours running it seems ok (42Deg C) not very hot to the touch and the volume of air was  plenty enough to remove the chips from the slots at 12mm depth.
So for now I'm happy, but don't know how well the piston rings will hold up over time, and only time will tell. It is very quiet (sounds like a little wobbler steam engine running on air)

Five plates done so far.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 03, 2018, 05:09:04 am
Another small update.
The ER32 collet Adapter has come as well as a MT3 collet chuck for the lathe (just need to make a Drawbar).

In the picture I've placed the new base plate along side of the old one just to show the difference.
This so that, when the time comes to upgrade the controller to a PI for the AI it should be a bolt in replacement
with no further machining needed.(Hopefully).

Dave
Oh one more thing, I think I was overthinking what might go wrong with the compressor as it has worked well
and I had to restrict the flow a bit as chips were getting all over the shop I 'm going to have
make a shield or use curtains to keep them in the rough area of the machine. ;D


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 23, 2018, 14:44:19 pm
Another small update.
I Finally installed the ER32 Collet Adapter to the spindle, and while I was at it added two small gussets to the Z Axis Back Plate that I'd cut out previously when doing the new linear rails but had not installed them.

The difference was night and day, I ran a 16 mm Endmill at 200 mm minute to do the outside profiles and the finish  was quite good.
I then ran a 6 mm Endmill at 250 mm minute doing another stepper motor mount (12 mm deep in A36) and with the mini compressor mounted to the spindle, it went very well (I was expecting something bad to happen).
The chip clearance was fine.

I have removed the base plate from one of the two turrets that I was using for testing, and fitted one of the new wider plates,and have made a back plate and tomorrow (with a bit of luck) will finish the top plate which will be a bit tricky as it has to have a battery hatch, Bluetooth Dome and a hole for the switch all have to be water proof.

I've ordered a Acrylic Dome for the Buletooth Module which hopefully will come in a couple weeks, and will give me time to paint all the parts and fit the micro-controller and battery holder and battery management module.
As  I've found time I've cut more of the side plates and hope to finish them by the end of this week.
I've got squaring the stock down (in the shaper) to a fine art now. ;D
Dave



Title: Re: Automatic tool changer for the lathe
Post by: dave benson on September 29, 2018, 14:05:21 pm
Another small update

I've finished all the machining, except the recess for the Bluetooth module, which won't arrive for a couple of weeks and I don't want to machine this until I get it in my hands on it and measure it properly. (I might do a little engraving for the on/off switch and a serial number) and have ordered a 1mm endmill for this.

What I'm going to do now, is completely disassemble it and paint all the parts separately and then install the electronics and perform the battery tests.

I'm still cutting the plates for the other turrets, it's a slow process and there are many to do.

On a side note, since installing the ER32 Collet adapter, I can't use the old method of setting the Z height and have been using the (ground pin method) to set it.
However sometimes I've hit the down button instead of the up button ::) and have damaged an end mill this way, and had a few near misses, so I've made a tool height setter and modified a probing routine to suit my own needs.
I should have done this earlier as it makes the job of setting the tool height a breeze.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 09, 2018, 14:28:39 pm
Another small Update

While waiting for the BlueTooth Dome, I machined the pocket for the On/Off switch, and tried out the Auto-leveler function of G-code Ripper.
And am pretty pleased with the result (I used one of George Races Stick Fonts) and have to say that the file was huge, but worked very well.

I also prepared the wiring and fitted the micro-controller and drilled and pinned the front Bearing Plate to the Base plate so that the turret can be
taken apart and serviced and put back together with the registration correct for the indexer position and correct Center Height.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 10, 2018, 22:50:59 pm
Well It pay's to be patient, a couple hours after I posted yesterday, the Bluetooth dome turned up
and the measurements were 47.5 mm dia by 29.5 mm tall (Advertised measurements 50 X 30).

Dave


Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on October 10, 2018, 23:08:39 pm
AHAH!  The BOX was 50 x 30!!!  ::)

Good on you for waiting.

Lloyd


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on October 11, 2018, 13:25:37 pm
Hi LLoyd

When I order from Hong Kong  or China directly, most of the descriptions are ok, but when ordering from Singapore or Malaysia I'm a bit wary as they are mostly shop fronts which take your order and then order it from China and may have never have Actually had the object in their hands. (This product was directly shipped from China)

Hong Kong has the fastest Shipping and sadly the longest wait was from within the country (Darwin) where they must still deliver by Pack Horses and Camels.
The product looks good though, so I'm Happy, the only thing is it presents a bit of a challenge to fixture for, as it is a Dome shape.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on November 18, 2018, 13:26:33 pm
Another small update.
I made a mandrel and machined the Bluetooth Dome, and then undertook the battery tests.

I used three different Brands of batteries.
Panasonic     3200 mah.   4 off
Borruit          4000 mah.  8 off
No Name       6000 mah.  8 off.

The Panasonic all lasted through the tests  6 cycles ---> 724 tool changes continuous.
Of the others 7 failed to recharge after the first cycle. And usually failed early at around 240 tool changes.

It just happened to work out that one of the three batteries in a set usually failed, and the other two were ok. 
The rest that got through the first cycle went fine and did 710 tool changes even though they were rated at higher capacity than the Panasonic’s.
 
Lesson learned  The Branded batteries worked out cheaper in the long run.

One thing to note is this test does not give a good indication of  how many tool changes to expect
during the normal course of  operation, because the turrets have a Idle current of around 284 ma.

I've been using the turret for not quite  2 weeks now and one night accidentally left it on, and in the morning the batteries were flat and I had to swap them out for a new set to carry on.

Yesterday the left handed turning tool came, so I've fitted that and made a Boring tool holder for my 11 mm Boring Bar and will make one to suit a ¼ inch that I have as well.

I've ordered the Bandsaw I spoke about earlier (the small one) which can be used Vertically as well as Horizontally which hopefully will stop a lot of grinder work in making the tool rests.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: lloydsp on November 18, 2018, 13:34:32 pm
'Tis a pity you can't rig up some sort of inductive battery charging system, so that whenever the machine is in its 'home' position, the batteries are recharging -- without wires!

Lloyd


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on November 19, 2018, 00:41:54 am
Funny you say that, I'm subscribed to some of the Uni EE departments around the world (just to see what's on the Horizon) and depending on the application there are a few different methods to do this.

Perhaps a few weeks ago now, on the Autoline show on You tube they had a guy discussing
this idea for EV's, coils buried in the highway were a non starter, but at home and in large employee car parks made some sense.
And from the figures he quoted the efficiency of near field charging wasn't as bad as I thought.

As to the turrets, well frankly I don't know if I have the Technical savvy or the room in the turrets to do this.
For now I'm going to “stick to my knitting” and try to improve my systems and processes as I can't keep up with my own self imposed schedule.

One thing I am going to do is (from a piece of received feedback) is to move the Indexer securing
bolts off the centre line by 4 mm, so that it is easier to adjust it, if for example you run the turret into the chuck and the overload bolt releases then you have to reset the centre height.

To do this you must release the indexer and place the adjustment rod under the tool opposite the
tool that's going to do the cutting and tighten up the overload bolt to around 50 ft/lbs.

But if you forget to release the indexer you will move the indexer out of position. And then have to reset it, and as the indexer is very sensitive to small misalignment's this will cause it to play up.

This means having to take the side covers off as well as the top cover, which is a pain in the butt.

If I had thought about this better, I would have offset the M4 button head screws (from the centre line of the Indexer wheel ) which would mean just having to undo the top cover and sliding it to the side and you would have easy access to the screws without having to remove the side covers as well.
So I'm already up to Mk4 Turrets and hope that there's no MK5's.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on November 24, 2018, 23:18:53 pm
Another small update

In the picture, is a small test piece that was done with fusion 360, previously I've been using the wizards in Mach3, which on the whole have been good to work with and for more complex tasks.
I've been using Ezilathe and importing the .dxf from CB and producing a file.
In this file I've selected CSS (constant surface speed) and tried to get most of the operations done with the Gcode

I made a mistake with the OD by selecting too small a cut for the finishing pass, the original depth of cut for the roughing pass produced a far better finish.

The ID boring went well and the sizing for the bushing was good.
The job was mainly to get fusion to produce Gcode that worked with the turrets.

What I found was with (using the wizards and Ezilathe) I needed a G53 in the Tool Change Macro.
But with fusion this wasn't necessary and I had to remove the G28's But all in all it wasn't too bad.

It’s funny you know, I've got six tools now to choose from, but more would be better, so in the next few weeks I think I'll make a Gang tooling post  to hold a centre drill and some smaller sized drills up to 6 or 8 mm, as the aim of the game is to get the lathe to do as much as possible of the work.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on January 03, 2019, 21:42:33 pm
Another small update.
Santa delivered a Bandsaw for Xmas (I love Santa) They are sold here as a Saber bandsaw (someone forgot to take out a few references to Grizzly in the manual though ;D)
Mechanical Hacksaw cut time 17 mimutes for a piece off 130mmx12 mm thick  Bandsaw ---> 7 and a half minutes.

I've ran this particular Turret for 3 or four weeks now, and am on the whole pretty happy.

I did part off a few Indexer Bases (I've had mixed results with the Tool in the tool post) and the job cut like butter.

I had some feedback stating  that it would be nice to (when setting the tool height after a crash) not to have to
release the indexer manually through the interface as this step could be forgotten and while leads to no damage
could (has) lead to the indexer moving as the overload bolt is secured and then must be reset which is a pain in the butt.
My first thought when this was mentioned was well don't forget, but after thinking about this for a few weeks
and watching a video about (Lt Murphy) from  Murphy's law  fame. he was a real guy and I discovered that even
Wikipedia had the commonly stated version of this law but this is not quite right. sensor plugs on a manned rocket sled should be polarised

Anyhow I decided to eliminate the step of manualy releasing the indexer, and so redesigned the Indexer completley and have a test turret where you don't have to do anything just set the centre height and tighten the bolt.

It is a Twin Pawl mechanism with automatic wear compensation and should not have to be adjusted for the life of the turret.
I had origionaly wanted to do this, but could not figure out how to do it. This time it was easier as I had spent
a lot of time on the turrets and watched thousands of tool changes.
Dave


Title: Re: Automatic tool changer for the lathe
Post by: Bob La Londe on January 20, 2019, 17:48:55 pm
Some nice work Dave.  I say Kudos to finally getting a horizontal bandsaw.  I remember when I got my first one.  A little 4x6 Harbor Freight unit with just gravity feed and a spring to relieve over pressure.  Its another machine that can work FOR you while you do something else.  I have since picked up a 7 x 10 with pneumatic feed control, but I still have my 4x6 attached to the end of a roller table.  When I made my very first bandsaw cuts I was ecstatic. 

That sneak up to dimension on the finish pass has bitten many a lathe operator.  With my limited knowledge base I have found (manual turning) that I get the best results by varying depth of cut and feed rate until I find the right one, but before I get to dimension.  When I get a good finish I mic, take another identical cut and mic again.  This tells me to finish to the dimension oversize that allows me to take the right final pass for a good dimension and finish quality. I don't have enough experience that I would have enough confidence to go straight to CNC with a turned part.  I think if t was a massed produced part I'd either CNC a couple prototypes and then go back my CODE to make adjustments before starting the production run, or I would make one or two pieces manually and take notes to use when I coded the part for the production run.  

Again, very nice Dave.  


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on January 21, 2019, 06:50:23 am
Thanks Bob

Yeah, getting the Band-Saw has made life much easier, the machine is built with much better quality standards than the Lathe
I bought perhaps 10-15 years ago. I really (to and fro'ed ) over getting this one, or a bit bigger one (like David's), and finally decided
on this one because, I wanted to do vertical cuts as well as horizontal.
 
This has helped on some parts (cutting vertically that is), where I've more or less cut the part out, close to the final dimensions on the Band Saw
and cut at full depth using the shrinking toolpaths strategy with a fixture. 

I've no complaints it works well and is quiet and fast.

As to the Lathe making good parts, I start off by taking a test cut and measuring with the Mic and checking that with the DRo's.
Indicate X and Z in. as I'm mostly using Carbide tooling, I've found that there is a minimum depth of cut for these, so what I do is
arrange the cut order so that on the final cut, I've got enough meat to cut and get a good finish.

In Fusion you can also specify the number of spring cuts, which varies with the stock Dia and the amount of stickout from the chuck
or whether the work is supported or not. This is mostly knowledge gained from trial and error.

In general I try to get "C's and 6's" from the cut and this pretty easy to get, because I set the feedrate and
then adjust the RPM's to suit. Then use these values in Fusion as a guide and sometimes adjust these slightly
at the Lathe.
I've been experimenting with CSS constant surface speed lately, and will be incorporating this into my code from now on.
I've found it an order of magnitude easier to hit tolerances with the lathe compared to the Mill.

Bob, once you have CNC'd the lathe, you won't look back, for me what makes using the lathe so enjoyable is that it's very repeatable
so that you can set up a file say for a 12 mm thread from 16 mm stock for 15 mm length in 1018 sticking out perhaps 25 mm from the chuck.
I made a file for this and other thread sizes with the Mach3 wizards with a spring pass, so now I put the work in the chuck and touch off
make sure the turret is turned on (3 tool changes) press the button and walk away and do something else and when the machine stops
go and get the parted off stud.

I do this on a regular basis for different stud sizes and it just works. the biggest thing is to not get stringy chips
if you can get your chips, if not "C's" and "6's" at least a manageable size then you can leave the machine to make the part and do something else.

What I do for ID boring for a bearing is use the carbide boring bar to rough (biggest cuts I feel comfortable with)
to almost size and then use the Hss boring bar, and sneak up on the size often at this stage I let the material cool back down
to ambient temp before measuring and taking the final cut.

I've received the ER11a collet chuck and when I get time, I'll make a gang tooling post. well put it the ToDo list anyway.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on January 21, 2019, 06:53:53 am
What's happened Lately with the twin pawl setup, I have mechanism going now, although it's been a tale of frustration and woe really.
What I discovered while assembling and testing was that the two pawls were not identical close but no cigar as when they were put
back to back and indicated concentric, some of the pawl teeth did measure up (I discovered this as the secondary pawl is operated by a cam)
of 1.5 mm throw and it's angular position when the pawl is locked up,is a good indication of how accurate the machining was at each tooth of the pawl.
When I did the Z Axis upgrade, I also checked the Y axis as this one showed up as the culprit when I did the drilling and machining tests a while ago, and replaced the motor couplers with solid ones.
 
I didn't know what to do for a while as I've checked the Y Axis many times and it always seemed ok, then I hit on an Idea and placed the Z Axis resting on a bit of wood on the machine vice and stalled the motor out, and saw that I had at the top of the Z Axis column 0.07 mm movement in the Y direction.
 
because this was late at night I found a bit of heavy wall 2 inch tube about 3\4's as high as the column and made a temporary brace, I was now down to 0.03 movement.
 
The next day I made a brace out of some 130 mm x 12 mm 1 m flat bar, and then made a new pair of ratchet wheels, and while not still not perfect
are within, (I'm guessing) perhaps 10 degrees  on the adjustment cam which (because of it's small throw tends to amplify the error so it's easy to see).
The allowable limit for the mechanism to work is at around 80 degrees + or - 5 degrees so that it can't be back driven.

I also had to heavily modify the Gcode by putting the machining tabs in strategic places where they were easy to cleanup but provided enough support for the following mops.

And in the first profile mop using an extra bit of cutwidth to help clear the chips as well as a second finish mop at full depth (tangent leadin)
and then using the collision detector to clean up the root of the teeth  with a 3 mm end mill (3 mops per tooth each with different Roughing clearance ) to sneak up on the size and not overload the endmill.
I then did some hand optimisations to stop unnecessary moves to the clearance plane.

Two thing's I noticed while doing this file were:

I had a lot of copy and pasted mops where I wanted to change only one or two of the values, and this took quite a lot of time.
I'll look into this when I have time.

When Coping a profile mop (6mm EndMill that had Machining Tabs) and then changing the diameter of the endmill and regenerating the code for a 3 mm endmill
the size of the machining tab changed (got smaller) and as this mop ran directly after the previous one (with a wider machining tab) it would have most likely broken the cutter.  So something to look out for and adjust when necessary.


Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 18, 2019, 03:43:28 am
Another small update.

Well after doing all that work on the machine, I set out and made some more secondary ratchets, two at first and measured them.
They were both identical two each other, but unfortunately were still 0.07 mm out in the Y Axis, which gave me the irritations no end as I thought I had fixed the problem.
I then removed the table, stripped the whole thing down removing the ball screw and the Ball-screw bracket that attached it to the table and finally found the problem.

The Ball screw bracket is attached to the table with a tapered spigot (with an M8 bolt), I'd checked this many times as its  easy to do and it was always tight.
It turned out that the spigot (cast iron) had a hairline crack about half way up, which meant that when I checked it, it was tight but the bottom half of the spigot, which was still attached by the bolt threads and captured in the tapered hole could move a small amount.

If I hadn’t taken the table completely apart I don't think I would have found it.
Anyway I re-did the Secondary Ratchets and they work well now on the workbench test turret.

I did some more work on the Auto tool identification, and it turns out to be relatively straight forward accurate and repeatable.
I have begun to look at the Auto tool touch off feature and as usual (The Devil is in the detail) as two cameras would be required both running without IR filters.

The last item on the list is compensation for tool wear, and also for setting a new tools offset in the tool table automatically.
This looked like a mission impossible for a home gamer, until I saw a guy on  you-tube hack a older type laser diode and use it for Interferometry.

Part way through the video I realised that I could apply this technique to this problem, And I'm sure that you could have heard my jaw drop half a block away.
After looking at the rest of his videos as far as I'm concerned this guy is in the Genius category.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: EddyCurrent on March 18, 2019, 10:32:45 am
Dave,

Maybe the tools could be barcoded ?


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 18, 2019, 12:38:41 pm
Hi Eddy
I'm sorry, I didn't make myself clearer, it's sort of buried in too long a of a post.

The blue square in the picture indicates a positive match between the image stored in the plugins
tools dir and a tool that would be in the turret tool slot.

This particular method is called feature mapping and  uses a technique called 'Speeded Up Robust Features'  SURF for short.
The really good thing about this approach is it is scale and angle invariant meaning that the tool can be found even if the
camera is of at an angle from the turret or is up close or far away.

This part of the turret software works accurately and repeat ability, and has not failed once to identify a tool.

There are other approaches to identifying objects for instance Colour and Shape and Outline, Bar codes QR codes ect, but I found these methods to be less than optimal and as this process is critical to the to the turrets performance it has to 'Just Work'.

One fly in the ointment was that some of the surf routines are patented, so it took  a very long time to find an open source alternative that was bullet proof.

When you first install the turret, you teach it what each tool looks like by selecting each tool that telling the turret to take a picture of the tool and entering the tool description (the same as the description in the tool table in mach3)  and then every new tool from then on.

For example as  Mach3 is running a Gcode program, it may call for tool  number one  (in my case this is a Right Hand Turning insert tool) and after the turret has changed the tool it will check that you have indeed a Right Hand Turning tool in that particular tool slot, and if the tool turns out to be a Boring Bar or something else then the turret will
cycle through the other tools looking for a Right Hand Turning Tool  (you may have just placed it in another tool slot) and if it finds the tool it will use it.
Else it will stop the lathe and flag an error and wait for you to put the correct tool in the tool magazine.

This is the stage I'm up to now and am very happy with it, the next stage is to do Automatic Touch Off which is quite a big deal (difficult to do)  along with tool wear measurements using interferometry.

The only other thing I would like to look at is temperature compensation , for example if I have to whittle down a lot of material in preparation for something critical like a bearing fit then I have to leave the job until it cools back down to ambient temp before measuring it again to get the correct size.

There is a Kickstarter project where they have a camera that can take a Fleur lens (and is not that expensive) with which I could take an  accurate temp of the workpeice.

 Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 26, 2019, 12:52:22 pm
Another small update.

I've been doing some more testing of the vision capabilities of the software, and in the pic below
ran a test with a cheap $8  webcam hand holding it above the test turret inside, and it seems pretty
 able to detect the tools even though my hands were a bit shaky and the image is a little out of focus
because of this and at 70 to 80 deg to the origional picture orientation.

I'm now in the middle of making a rack to run along the lathe for the camera to sit on, and have ordered a
middle of the road camera from Microsoft.

I've also purchased a new lathe chuck, a 160 mm four Jaw Independent, as the one that came with the lathe
is terrible, just have to make a Backplate to suit the spindle 39x4mm thread.

I've also looked into the measuring tool wear thing, and there are quite a few issues to overcome some electrical
(High gain Opamps and filtering)  and although I plan to be measuring an order or magnitude less (maybe two) then Ben over at the Applied Science Website.

And some mechanical details as well. I sorta guess that I've have trouble keeping the vibration at bay while staging the sensor. Anyway I've ordered some Sony laser diodes (the one's Ben  is using and pointed to ) are getting long in the tooth.

There were still some at Jamco and Amazon and one box of one hundred on Ebay, but I've managed to find these
which are a bit more plentiful and cheap.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on March 30, 2019, 08:26:03 am
Another small update.

The camera turned up a couple of day's ago, and on the whole am pretty pleased with it.
It did take some time to set it up correctly for this task, and I've done many tests with different
settings for resolution frame rates,auto-focus ect, It was a lot of fun chasing the optimum settings
down, but to keep the thread short won't go into the detail's.

I've made a new tabpage where you can set up and test the camera at the lathe for different lighting,
and camera positions.
You can elect to use the computer vision or not.
If you do, then you must teach the turret what each tool looks like using the capture tool button
and save it to the turret tool dir.
At the moment if the turret finds the tool slot empty or another tool in place of the required one
then it will stop and wait to operator input, but I will code for it to either look for the tool in another slot and if
it finds the tool then adjust the tool alias table and continue on with the job .

I'm going to put the coding aside for the moment as I've bought some HRS 200x200x16 mm plate and a
piece of 1040 75 dia x 100 long round bar to make the backing plate for the 4 jaw chuck.
and plan to make a boss and press it into the plate and machine it, and then drill the mounting holes
on the mill.

Dave


Title: Re: Automatic tool changer for the lathe
Post by: dave benson on April 19, 2019, 11:15:08 am
Another small update.
I used the twin pawl setup now for a couple of weeks, and it has performed well, as it locks the turret plattern rigidly.

I did have to ditch the solenoid activation as this new mechanism  requires more force to operate.

I tried very hard to keep using the solenoid activation method, as I was trying to make the turret as a whole
simple and robust, and if anything did go wrong it would be cheap to fix with easily available parts.

However the solenoid would have required a torque multiplier (like the capstan in the original indexer)
adding to the mechanisms complexity,cost and extra failure points.

So I Servo'd the secondary pawl, which added to the cost (10 times the solenoid cost) it proved to be a great boon though
as the energy budget required dropped significantly.

The Idle current has gone from 286 ma to 113 ma giving about 55 hrs. to remember that you left it on.
This had nothing to do with the servo but rather turning off all the peripheral clocks not needed and a few other power saving tweaks.

The number of tool changes has increased from 720 @ 18c to 1600 @18c using the same test procedure.

This was mainly brought about by not wasting power to energise the solenoid during the whole of the tool change
as the servo is used only open and close the latch. I also was able to add another 18650 cell to the battery pack
as the original indexer was in a different position preventing me from doing so.

I can't test much at the moment on the lathe as I've started to install a ball-screw like Steve has done with his build
and have machined the saddle and made some brackets, just waiting for a bearing block for the front support.

The laser diodes have not turned up yet, and I may have made a mistake as I ordered 405 nm ones rather than the 625 nm ones Ben used and on the weekend will talk to friend who ran his own a laser company for many years to see what his opinion on the viability of this Idea is.

Dave