Pocket from inside out

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Pocket from inside out

Postby garv123 » Wed Nov 06, 2019 11:18 am

Hi all,
As above, is there any way to set the start point of a pocket on the inside when using offset. I cant see any option for it. It was our default when using Artcam.
Using cut 2d pro now.
Basically when pocketing out plastic, a 40.4mm long pocket with a 20mm cutter, the cutter will run around the outside but the 0.4mm will wrap around the cutter and pull off before the cutter makes the final pass up the middle, if the first pass was up the middle this wouldn't be an issue.
This is just one example of the issue.

Any help appreciated.
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Re: Pocket from inside out

Postby Rcnewcomb » Wed Nov 06, 2019 8:33 pm

Can you post your CRV file? When I do a pocket it starts in the middle.
- Randall Newcomb
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Re: Pocket from inside out

Postby garv123 » Fri Nov 08, 2019 1:05 pm

Sample of a job attached
Attachments
10pe Shelves.crv
(145.5 KiB) Downloaded 9 times
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Re: Pocket from inside out

Postby Adrian » Fri Nov 08, 2019 1:41 pm

I expect it's generating the toolpath like that as it's so close to being double the diameter of the bit the toolpath would be cutting air for the most part if it started in the middle. If you change it to a raster with the profile option set to last it should work the way you want it to.
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Re: Pocket from inside out

Postby adze_cnc » Fri Nov 08, 2019 9:03 pm

Adrian wrote:I expect it's generating the toolpath like that as it's so close to being double the diameter of the bit the toolpath would be cutting air for the most part if it started in the middle.


Close. It's because the tool step-over is 60.2% (12mm) of the bit diameter (which is specified as 19.5mm not 20). Drop that step-over to less than 50% and all works as it should.

This is where having access to a test file makes debugging the problems so much easier.

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Re: Pocket from inside out

Postby Adrian » Fri Nov 08, 2019 10:08 pm

The raster toolpath with the original settings will be faster though. Generally for long skinny pockets I tend to favour the raster over the offset.
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Re: Pocket from inside out

Postby garv123 » Mon Nov 11, 2019 12:14 pm

adze_cnc wrote:
Adrian wrote:I expect it's generating the toolpath like that as it's so close to being double the diameter of the bit the toolpath would be cutting air for the most part if it started in the middle.


Close. It's because the tool step-over is 60.2% (12mm) of the bit diameter (which is specified as 19.5mm not 20). Drop that step-over to less than 50% and all works as it should.

This is where having access to a test file makes debugging the problems so much easier.

Steven


The stepover being less than 50% is a bit of a pain when theres more than just the skinny pocket in the job, it'll take a lot longer to do big jobs.

Same goes for using raster, if there is a L shape pocket it will be fast in one direction but slow to pocket in the other direction.

I'll start using raster for the long skinny pockets on their own for now. just need to try and keep these 3 CNC routers running as smoothly as possible all day.
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