Struggling with step over percent

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m12lrpv
Posts: 14
Joined: Sat Feb 09, 2019 10:13 am

Struggling with step over percent

Post by m12lrpv »

I am struggling to get 100% material removal in pocketing operations.

In the 3 images I have 3 step over % values and the paths generated. 100%, 80% and 79%

More often than not the path generated will not fully remove the material for a pocket. This can become a problem if i'm trying to choose a certain stepover % for the purpose of dealing with surface finish, safe feed rates for the cutter and material or any other reason.

How can I quickly find the percentages values that will result in 100% removal without stepping through every possible value from 1 to 100?
or even better... how do I force it to remove all the material for the value I specifically want?

OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.22522 (Git)
Build type: Release
Branch: master
Hash: d8e476ef428017900dfe0f9359ba448503c216f9
Python version: 3.8.5
Qt version: 5.12.6
Coin version: 4.0.0
OCC version: 7.4.0
Locale: English/Australia (en_AU)
Attachments
Centre_removed.jpg
Centre_removed.jpg (265.87 KiB) Viewed 1461 times
Centre_not_removed_79.jpg
Centre_not_removed_79.jpg (226.03 KiB) Viewed 1461 times
Centre_not_removed.jpg
Centre_not_removed.jpg (246.31 KiB) Viewed 1461 times
chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Struggling with step over percent

Post by chrisb »

Try current 0.20. It removes here always all material.

OS: macOS 10.16
Word size of FreeCAD: 64-bit
Version: 0.20.26155 (Git)
Build type: Release
Branch: master
Hash: 0926a4148bcff11249fd4f56bc30256102ffe105
Python version: 3.9.7
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.3
Locale: C/Default (C)
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GeneFC
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Location: Punta Gorda, FL

Re: Struggling with step over percent

Post by GeneFC »

m12lrpv wrote: Thu Oct 21, 2021 5:49 am I am struggling to get 100% material removal in pocketing operations.
It seems you may be confusing the path shown for the tool center with the actual cutting area.

The entire pocket should be removed regardless of the stepover percentage. The difference due to stepover will show up only in the paths for the inner areas of the pocket, not the perimeter.

Gene
m12lrpv
Posts: 14
Joined: Sat Feb 09, 2019 10:13 am

Re: Struggling with step over percent

Post by m12lrpv »

GeneFC wrote: Thu Oct 21, 2021 1:50 pm It seems you may be confusing the path shown for the tool center with the actual cutting area.
No, I actually ran those paths on the machine and the center material is not removed.
GeneFC wrote: Thu Oct 21, 2021 1:50 pm The entire pocket should be removed regardless of the stepover percentage. The difference due to stepover will show up only in the paths for the inner areas of the pocket, not the perimeter.
I agree 100%. The entire pocket should be removed hence my post.
chrisb wrote: Thu Oct 21, 2021 6:05 am Try current 0.20. It removes here always all material.
Thanks Chris. I'll take a look.
GeneFC
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Posts: 5373
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Struggling with step over percent

Post by GeneFC »

Sorry, I guess I did not understand your post. :oops:

In any case I just tried a test using a very recent version 0.20. Everything worked fine except for the Spiral pattern. That pattern showed the missing center problem for a stepover of 100%.

I have never used spiral, and I do not know how it is supposed to work. Neither the x-y path or the z-path looks like a spiral.

Gene
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