3D pocket produces nothing of consequence

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ericcsforge
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Joined: Thu Jun 17, 2021 11:28 pm

3D pocket produces nothing of consequence

Post by ericcsforge »

Hi. I am trying out FreeCAD since somebody has suggested that it could be used as a toolchain for our CNC knee mill running LinuxCNC. I am having trouble getting Pocket 3D working.

The problem is that selecting the bottom of the pocket and clicking the Pocket 3D tool produces a trivial tool path consisting of just one G0 command. Obviously, this does not do any cutting. I am using the 0.19 appimage that comes from the download section of the freecad website.

I did a search of the forum, and although there are a lot of problem reports, oddly enough, only one seems to match mine. I performed the suggested operations (set OCL support in preferences, set up a expermental boolean flag in Mod, and use Surface 3D instead). This does produce something. It creates a huge flood of cutting paths, most of which are superfluous. When the simulator is finished running, it only cuts part of the pocket. There are far too many operations and it would take an extremely long time to run on the mill. It was unclear if the OP got his project running. Does anyone have a clue about what could be going wrong?

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chrisb
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Re: 3D pocket produces nothing of consequence

Post by chrisb »

Hi and welcome to the forum!

I am not sure, if the simulator handles 3D pocket correctly, so you better look at the paths. Can you upload the file and mark somehow what goes wrong and what you expect?
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bmsaus4ax
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Re: 3D pocket produces nothing of consequence

Post by bmsaus4ax »

ericcsforge wrote: Thu Jun 17, 2021 11:40 pm Hi. I am trying out FreeCAD since somebody has suggested that it could be used as a toolchain for our CNC knee mill running LinuxCNC. I am having trouble getting Pocket 3D working.
Could you attach your " .FCStd " file , it allows forum members to troubleshoot your problem. ( Attachments Tab below the text entry window)

In the case of the simulator, it has a limitation when displaying 3D paths. Only the leading half of the tool shape is removed from the stock, so the final display can look very wrong for some shapes although the code is correct.

I see chrisb has also posted while I was previewing my post, so you get the same answer twice
chrisb
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Re: 3D pocket produces nothing of consequence

Post by chrisb »

bmsaus4ax wrote: Fri Jun 18, 2021 4:35 am so you get the same answer twice
Not really twice, yours was more precise. (Besides that I know the problem :) )
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ericcsforge
Posts: 8
Joined: Thu Jun 17, 2021 11:28 pm

Re: 3D pocket produces nothing of consequence

Post by ericcsforge »

Hi. I am attaching the file with the NULL 3D pocket operation. I suspect that this is already a known problem, and the solution will be to use 3D surface. I can also attach the failed 3D surface file to a later post.
Attachments
millclmp2poc.FCStd
(416.59 KiB) Downloaded 42 times
ericcsforge
Posts: 8
Joined: Thu Jun 17, 2021 11:28 pm

Re: 3D pocket produces nothing of consequence

Post by ericcsforge »

bmsaus4ax wrote: Fri Jun 18, 2021 4:35 am ...

In the case of the simulator, it has a limitation when displaying 3D paths. Only the leading half of the tool shape is removed from the stock, so the final display can look very wrong for some shapes although the code is correct.

I see chrisb has also posted while I was previewing my post, so you get the same answer twice
I checked the Gcode output. It had only one rapid G0, which did no cutting.
GeneFC
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Re: 3D pocket produces nothing of consequence

Post by GeneFC »

I am not sure what steps you are using. I loaded your file, inspected the g-code, and it looked quite reasonable.

Capture2.PNG
Capture2.PNG (25.61 KiB) Viewed 1814 times

This is the screen shot of the paths generated.

Capture.PNG
Capture.PNG (46.98 KiB) Viewed 1814 times

I believe you will need to be more explicit in exactly what you are doing that leads to "nothing of consequence".

Gene
chrisb
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Re: 3D pocket produces nothing of consequence

Post by chrisb »

You can't use a drill for 3Dsurface. I changed it to the 6.35 endmill.
And I changed the boundary adjustment to nearly the diameter of the mill.

Besides: Please remove the artefacts from the simulation before uploading. It reduces the size of the file to less than 1/10 here.
SnipScreenshot-332942.png
SnipScreenshot-332942.png (47.06 KiB) Viewed 1796 times
Attachments
millclmp2poc_cb.FCStd
(39.13 KiB) Downloaded 43 times
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
ericcsforge
Posts: 8
Joined: Thu Jun 17, 2021 11:28 pm

Re: 3D pocket produces nothing of consequence

Post by ericcsforge »

GeneFC wrote: Fri Jun 18, 2021 7:50 pm I am not sure what steps you are using. I loaded your file, inspected the g-code, and it looked quite reasonable.


Capture2.PNG


This is the screen shot of the paths generated.


Capture.PNG


I believe you will need to be more explicit in exactly what you are doing that leads to "nothing of consequence".

Gene
Hi Gene. How did you prepare this output??? I used the "Post process" button on the lower tool bar. It produces a bunch of gcode. I am only complaining about the last block, the 3D pocket operation. Here's the copy and paste:

(begin operation: Pocket_3D)
(machine: not set, mm/min)
(Pocket_3D)
G0 Z15.000
(finish operation: Pocket_3D)
(begin postamble)
M05
G17 G54 G90 G80 G40
M2

Note that the Pocket_3D operation only consists of a single command: G0 Z15
This is not going to do any cutting. I cannot see the appropriate section in your screen grab. It appears that it is a .png file and is not scrollable.

The second .png file shows the same tool path that my file does. The profiling, slot, and drilled hole worked fine. The nose of the clamp appears not to have been touched.

Sorry about the unclear nature of my post. I should have prepared a file with only one operation, the 3D one.
ericcsforge
Posts: 8
Joined: Thu Jun 17, 2021 11:28 pm

Re: 3D pocket produces nothing of consequence

Post by ericcsforge »

chrisb wrote: Fri Jun 18, 2021 8:40 pm You can't use a drill for 3Dsurface. I changed it to the 6.35 endmill.
And I changed the boundary adjustment to nearly the diameter of the mill.

Besides: Please remove the artefacts from the simulation before uploading. It reduces the size of the file to less than 1/10 here.
SnipScreenshot-332942.png
This is perfect! I take it that you did the job with 3D surface. When you say "artifacts", you mean the cut material?

By the way, I tried with all of the tools. None worked, even the endmills.
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