Pocket goes bad

[yorik503]

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 (42.61 KiB) Viewed 213 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!

[drmacro]

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.

[yorik503]

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]

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.

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]

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.

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]

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)