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Author Topic: Constant feed MOP  (Read 1142 times)
dh42
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« Reply #15 on: November 25, 2019, 21:37:03 pm »

Hello

Quote
I would consider it before adding it to the plugins page.

Ok, I'll have a look and try it ... currently I just have a quick overview ...

++
David
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dave benson
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« Reply #16 on: November 25, 2019, 23:28:18 pm »

David
Quote
(and when I understand what is it exactly )

If you pm me, I'll explain the reasoning behind using the troc mops (peel milling) in industry
and why It was invented (a long time ago now)  to increase the speed of machining, for example
as you can see in the pic a troc mop (properly set up) will (except for two edge cases) always be
faster than a plain vanilla mop always.

The feed rate adjuster when applied to a normal pocket mop will get you roughly a 20%
decrease in machining time, when applied to a troc mop this This can be as high as 60 %
faster to do the same pocket. After all this is what peel milling was invented to do in the first place.

So there's not much gain applying it to a normal CB pocket, vanilla CB profile mops do benefit from
the feed rate adjuster and there is more to gain with for example a Engraving mop where the geometry
varies in Z height or the 3d mops.
But I need to do some more work on this (I can not remember where I was up to when I stopped development)
and would have to have a look when I get the time.
Which I'm very short of right now.
It's on the to list, but that is getting quite long. Cheesy
I'm done here now David, so if you have any issues getting it to work, Just pm me.
I'm more than willing to help you sort things out.

Dave


* comparison between Troc mop and plain pocket mop.PNG (102.28 KB, 1351x325 - viewed 18 times.)
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dh42
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« Reply #17 on: November 28, 2019, 01:39:57 am »

hello Dave

thanks Wink ... currently I still not tried it ... I spend time to convert all my videos on forums and websites from swf (flash) to mp4 ... because flash will no longer supported by browsers in 2020 ...

Do you think that trocho milling is also interesting for milling wood ? (99% of my CNc usage is for wood and derived)

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David
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Bubba
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« Reply #18 on: November 28, 2019, 02:41:07 am »

Do you think that trocho milling is also interesting for milling wood ?
***************************
David, that's how I use it. Because I can, in most cases double the depth of cut per pass vs CB native conventional pocket MOP, and I route mainly hardwood.
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My 2¢
dh42
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« Reply #19 on: November 28, 2019, 02:49:16 am »

Hello Bubba

thanks, good to know !

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David
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dave benson
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« Reply #20 on: November 28, 2019, 03:38:03 am »

HI David\Bubba

My experience with wood is almost non-existent, so you'll have to take this with a grain of salt ,but  I think that if you are using MDF or a material with no grain and using the troc pocket mops and the adaptive feed rates then you should be able to decrease your cutting time by a factor of 3 or 4. It really depends on the geometry, which if you choose to try it and like it I'll try to put down some simple rules to follow to apply it effectively.
I was able to triple the Depth of cut and between 2 to 4 times the feedrate on my job. 1018 mild steel. 

Hallelujah Bubba, I realise now that you are not some random Muppet on the interwebs
pretending to know what you are doing.

I can tell you that with your particular job, you can increase your feed rates by at least a factor of two maybe more depending on the cooling issue.
I know in my case the tooling is lasting a lot longer as well. TiAn 6 mm four flute endmill.

The issue I ran into in the end of the trials was that I had no flood cooling, and don't have variable speed spindle control but for me a three times decrease in machining time just using compressed air to cool the tool (and at the end of the trial's I started flooding the pocket with coolant) this did give me some issues with evacuating the chips, so I only use this for roughing  tool paths and clean up with a full depth normal profile mop and this was more than enough to keep me happy.

I'm not kidding about that smile, to see the mill use the troc mops and apply adaptive feedrates in real time is really quite gratifying.

Dave
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Bubba
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« Reply #21 on: November 28, 2019, 13:36:54 pm »

Hallelujah Bubba, I realise now that you are not some random Muppet on the interwebs
pretending to know what you are doing.
*********************
Dave, I've been doing this (machining) the whole life. I'm in my seventies so I experienced thing or two by running just about every conventional machine, sprinkled nc and cnc type as well. By running conventional machines over time, you develop feel for it,capability and efficient cutting tools usage. What I like about the troch MOP most is the initial start, it is very easy on the machine (a specially my wobbly diy router) and the cutting tool as well. The CB pocketing MOP, it does have its place and I use it as well(it nice to have a choice) lacks the smoothness when it comes to stepover. For instance try pocket circle any diameter @.250" deep with CB MOP vs Trocho MOP and observe.. When I had my tabletop
mill (sold about two year ago) converted to cnc, machining mostly aluminum trocho mop was the choice because of its overall efficiency, considering, time, tool vear and overall performance. So my believe in using the troch MOP, as they say in this part of the world' load the wagon, don't worry about the mule'.  Wink Wink Cheesy Cheesy Grin Grin  
« Last Edit: November 28, 2019, 13:38:47 pm by Bubba » Logged

My 2¢
kvom
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« Reply #22 on: November 28, 2019, 13:56:56 pm »

I'm a big fan of the trocho mops.  Being able to use the side flutes is for me a major factor in tool life.  I really enjoy the pocket MOP for machining larger round holes in a single MOP vs. drill + profile mops.  I use the profile version less often, but where it really shines is removing material in aluminum where a slot is likely to result in chip welding.
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Bob La Londe
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« Reply #23 on: November 28, 2019, 14:08:13 pm »

Well since Dave has now publicly branded me as a random Muppet and a pretender on the "Interwebs" I'll have to look at the trochomops again, but it sure seemed like 30 reversals was a lot slower than 4 in mixed and all that extra travel time was wasted movement in conventional or climb.  I guess everybody but me has a machine with acceleration rates like a hammer blow.  LOL.  

Thank you for branding me a Muppet(r).  I always sort of associated with Beaker.
« Last Edit: November 28, 2019, 14:14:51 pm by Bob La Londe » Logged

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Garyhlucas
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« Reply #24 on: November 28, 2019, 22:18:28 pm »

I have to admit I have not tried the TrocoMOP either, but in building this new CNC Router for the FIRST Robotics team I am removing a lot more metal in pockets than I usually do.  So it is time to give it a try.

I think Trochoid machining was primarily driven by the change from having geared spindles to gearless or single speed spindles with VFD control.  Higher spindle speeds were the result with a loss of low end torgue to drive large diameter cutters.  So trochoid milling helps by using smaller tools at higher rpms with a deeper cut, which gets the speed vs torque range into the sweet spot for VFD powered spindles.  On our small hobby machines and for those of using a wood router for a spindle there is likely to be a lot of benefit.
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dave benson
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« Reply #25 on: November 29, 2019, 01:03:21 am »

Garry, you are correct, You'll be frankly amazed are metal removal rate you can achieve.
This is limited by three things.

1.. The power of your spindle.
2.. The power of your X\Y  steppers.
3.. The ability to remove the chips.

I conducted many trials, and found that the steppers were ok, but having no flood coolant
was a limiting factor and the ability to remove that many chips required this, so I had to be content
with only a 3 to 4  times decrease in machining time.

It won't turn a aluminium based router in a mill,but it will allow you to make the most out of it.
What I did was start out with a pocket mop in 1018 mild steel, which I had run many times.
140 mm/m feed rate .25 mm DOC .7 stepover.
Because of the High impulse loads (lots of radial cutter engagement in the corners) I had to set the feedrate to suit that, which was even pushing the machine and tool a little to much.

The Troc mops helped a lot allowing a greater depth of cut 0.5 mm DOC and 180 mm/m feedrate
I then applied the Feed rate adjuster which enabled me to increase the DOC to 1 mm and the
feedrate in the troc mop to 400 mm/m.

What the feed rate adjuster allows you to do is dynamically change the feedrates during the mop.
What this meant was I could set a minimum feedrate for the corners at 100 mm/m
and for the rest of the toolpath at 400 mm/m. They vary from 400 to 100 depending on the load on the cutter calculated from the geometry.

You can set the feedrateadjuster to dynamically change the feedrate into and out of the
high load areas per line of Gcode,(continuously variable feedrates) this is where the optimization comes from.

To see your machine act like it has a much more expensive controller is something to see.
Make no mistake, no other hobby software in CB's class can do this.

And because the feedrates are done in the Gcode it works with all controllers so even a GRBL
based machine can make use of it.

Dave
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