Author Topic: Corner Overcut For Pocket  (Read 3405 times)

Offline ThisAmplifierIsLoud

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Re: Corner Overcut For Pocket
« Reply #15 on: June 20, 2020, 07:05:56 am »
Indeed, a good idea, too !

+1 !
best regards

Bernhard

Offline Bob La Londe

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Re: Corner Overcut For Pocket
« Reply #16 on: June 20, 2020, 15:08:06 pm »
I don't think a small circle helps much since the cutter will still need to engage 100% as it goes in.  More important to control the feed rate for the corner overcut.
 

It rotates around a curve into the cut rather than just jamming it directly into the corner like a stick.  I have done it several times and the result is much less aggressive.  I even posted about it here, and made a video about making wrenches that covered it.  It helps quite a bit.  More than you would think.  Its a CAD solution to the problem.  I can understand why folks would be resistant to it since its a little bit more work to setup, but for me its worth it because I wound up make a bunch of those wrenches.  Its not an idea I was speculating about.  Its a concept I tested. 

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Offline Bob La Londe

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Re: Corner Overcut For Pocket
« Reply #17 on: June 20, 2020, 15:26:19 pm »
I don't think a small circle helps much since the cutter will still need to engage 100% as it goes in.  More important to control the feed rate for the corner overcut.
 

It rotates around a curve into the cut rather than just jamming it directly into the corner like a stick.  I have done it several times and the result is much less aggressive.  I even posted about it here, and made a video about making wrenches that covered it.  It helps quite a bit.  More than you would think.  Its a CAD solution to the problem.  I can understand why folks would be resistant to it since its a little bit more work to setup, but for me its worth it because I wound up make a bunch of those wrenches.  Its not an idea I was speculating about.  Its a concept I tested.

Here is a quick and dirty example that illustrates the point.  Typically I make the circle a very slightly larger diameter than the cutter.  The net result is a good fitting part that I can run faster with less chirp from chatter in the corners. 

In this example I used a 1/4inch (0.250) end mill and made the little over cut circle 1/100 inch larger (0.010).  It works with dead on size circles too, but by going slightly larger you all but eliminate chatter.

Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com

Offline Bob La Londe

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Re: Corner Overcut For Pocket
« Reply #18 on: June 20, 2020, 15:34:51 pm »
Both cuts overlaid on each over for comparison. 
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

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Offline jimmer

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Re: Corner Overcut For Pocket
« Reply #19 on: July 29, 2020, 16:50:20 pm »

+1 to the Request for Pocket corner overcut (with feed reduction?)

I don't buy the 'use a finishing MOP argument' following that logic you would remove the final stepover parameter. Or even why have a pocket MOP at all, just use lots of profile MOPS, they are free after all  ;D

Thinking about it, feed reduction on the profile corner overcut would be helpful. The problem is the jarring delta between a normal finishing cut stepover (0.1?) and the corner overcut full face.

Whereas when pocketing I'm taking a bigger cut eg 0.75 stepover and I'm already hitting full face cutting in every (square) corner.  So my feedrate is already one than can take full face cutting.   


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