Pocket goes bad

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yorik503
Posts: 4
Joined: Sat Nov 21, 2020 5:46 pm

Pocket goes bad

Postby yorik503 » Sat Nov 21, 2020 6:44 pm

Hi,

could you please explain why pocket operation does strange stuff to a body: it becomes black and the pocket got cut on side instead of being in the center. Please see attached picture and project. I tried several times, even use a cube from Part workbench, still it behaves wrong.
bad_pocket.png
bad_pocket.png (42.61 KiB) Viewed 212 times
Details:
OS: Debian GNU/Linux bullseye/sid
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.4.
Build type: Release
Python version: 3.8.3
Qt version: 5.12.5
Coin version: 4.0.0
OCC version: 7.4.0
Locale: English/United Kingdom (en_GB)

Thank you for the help!
Attachments
bad_pocket.FCStd
(22.81 KiB) Downloaded 8 times
drmacro
Posts: 2336
Joined: Sun Mar 02, 2014 4:35 pm

Re: Pocket goes bad

Postby drmacro » Sat Nov 21, 2020 7:03 pm

In Sketch001 where the arc and the upper horizontal are creating an acute edge and creating a convergence issue.

If you apply an perpendicular constraint between these two then al is good.
Attachments
bad_pocket_constraint.png
bad_pocket_constraint.png (152.15 KiB) Viewed 207 times
bad_pocket_good.png
bad_pocket_good.png (156.12 KiB) Viewed 207 times
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yorik503
Posts: 4
Joined: Sat Nov 21, 2020 5:46 pm

Re: Pocket goes bad

Postby yorik503 » Sat Nov 21, 2020 11:33 pm

drmacro, thank you so much, your advice helps!

Am I right that even if I would want to have sharp edge similar to that it will problematic? In real project I'm trying to do, I get sharp edge, but I can survive without it.
jmaustpc
Posts: 10525
Joined: Tue Jul 26, 2011 6:28 am
Location: Australia

Re: Pocket goes bad

Postby jmaustpc » Sun Nov 22, 2020 1:45 am

drmacro wrote:
Sat Nov 21, 2020 7:03 pm
In Sketch001 where the arc and the upper horizontal are creating an acute edge and creating a convergence issue.

If you apply an perpendicular constraint between these two then al is good.
Although that does appear to resolve the issue , it is doing so indirectly and is not actually the problem.
yorik503 wrote:
Sat Nov 21, 2020 11:33 pm
Am I right that even if I would want to have sharp edge similar to that it will problematic?
All I had to do was recompute the whole document without changing anything and it worked. Update your FreeCAD to the latest dev snap shot of 0.19 since it now has well over 6 thousand bug fix and new feature commits of code. It is way better than 0.18 and there is just no point in continuing with the older version.

As a general rule, you should always fully constraint your sketches, otherwise you have not fully described your object and you are more likely to have these strange issues. Unless you put it there for some other reason, there is no need for the construction circle in this sketch, you could have just directly constrained the arc with a radius or diameter constraint.

OS: Ubuntu 18.04.5 LTS (KDE/plasma)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.daily PPA
Build type: Release
Branch: unknown
Hash: 20649ec5292a31279f5593eccee2c5cd106bb099
Python version: 3.6.9
Qt version: 5.9.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/Australia (en_AU)
yorik503
Posts: 4
Joined: Sat Nov 21, 2020 5:46 pm

Re: Pocket goes bad

Postby yorik503 » Sun Nov 22, 2020 11:36 pm

jmaustpc wrote:
Sun Nov 22, 2020 1:45 am
All I had to do was recompute the whole document without changing anything and it worked. Update your FreeCAD to the latest dev snap shot of 0.19 since it now has well over 6 thousand bug fix and new feature commits of code. It is way better than 0.18 and there is just no point in continuing with the older version.
I tried that and it worked sometimes on that simplified example, but didn't work on my real project. I'll try to install 0.19, but I'm using debian and wasn't able to find easy instruction how to do that. I hope ubuntu package will work.
jmaustpc wrote:
Sun Nov 22, 2020 1:45 am
As a general rule, you should always fully constraint your sketches, otherwise you have not fully described your object and you are more likely to have these strange issues. Unless you put it there for some other reason, there is no need for the construction circle in this sketch, you could have just directly constrained the arc with a radius or diameter constraint.
The sketch was fully constraint in the real project, but it didn't affected the issue, so I didn't bother to do that in the example.
yorik503
Posts: 4
Joined: Sat Nov 21, 2020 5:46 pm

Re: Pocket goes bad

Postby yorik503 » Tue Nov 24, 2020 10:21 pm

I tried that with 0.19 from ubuntu and I got the same behavior again. But recompute helps always, I think.

Version I tried:
OS: Debian GNU/Linux bullseye/sid
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.
Build type: Release
Branch: unknown
Hash: 8d73c8f07fcbcb659cf073686fcf5149d31ec7ca
Python version: 3.8.6
Qt version: 5.14.2
Coin version: 4.0.0
OCC version: 7.4.0
Locale: English/United Kingdom (en_GB)