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Author Topic: Automatic tool changer for the lathe  (Read 2969 times)
lloydsp
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« Reply #30 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!  Cheesy

Lloyd
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EddyCurrent
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« Reply #31 on: November 12, 2017, 18:57:27 pm »

Good point  Grin  Grin  Grin

But wait a minute, what if the electronics required a totally ripple free DC supply  Cheesy
« Last Edit: November 12, 2017, 18:59:23 pm by EddyCurrent » Logged
Bob La Londe
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« Reply #32 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. 

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lloydsp
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« Reply #33 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
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dave benson
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« Reply #34 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








 
 


* steel1.png (1144.5 KB, 1000x750 - viewed 25 times.)

* freecad turret model Capture.PNG (41.53 KB, 479x387 - viewed 26 times.)
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Bob La Londe
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« Reply #35 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. 
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dave benson
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« Reply #36 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. 




* space maybe for rear tool post .png (1248.43 KB, 1000x750 - viewed 13 times.)
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dave benson
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« Reply #37 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  Shocked.

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
 




 


* One Turret Making Another (RapRap Style).png (1157.18 KB, 1000x750 - viewed 15 times.)

* Pawls done.png (797.46 KB, 1000x750 - viewed 14 times.)

* Work Done So far.png (914.07 KB, 1000x750 - viewed 13 times.)

* Lathe Tool Turret tool detection find tool tips.png (623.62 KB, 1000x789 - viewed 21 times.)
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dave benson
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« Reply #38 on: Yesterday at 05:47:45 »

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






 


* New Tool Plattern Ver3 plus sensor wheel plus Disk Brake.PNG (76.19 KB, 626x567 - viewed 7 times.)

* New Lathe Plattern Turret ver 4.PNG (48.96 KB, 664x560 - viewed 7 times.)

* turret NMBR 2 and ver3 tool Plattern.png (1152.94 KB, 1000x750 - viewed 9 times.)
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