To Flip or Not to Flip, That is the Question (Datum Planes)

[chrisb]

In the version shown below it is as run_the_race describes. thomas-neemann is right, that on creation of a DatumPlane in XY-plane the axis cross points initially in the right direction. However, it stays in that position even if the DatumPLane is moved.

OS: macOS 10.16
Word size of FreeCAD: 64-bit
Version: 0.20.25065 (Git)
Build type: Release
Branch: master
Hash: 4de2ad46b2b9c78ac2721a0dbea7c19306261095
Python version: 3.9.4
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.2
Locale: C/Default (C)

[run_the_race]

For me it is like this, if I start the datuplane in the xy plane, I can move and twist it as desired, it always corresponds to the coordinate system.

Okay I see, thats a point worth remembering. However in this case it is attached to some reference sketch geometry, not a plane.

[thomas-neemann]

However in this case it is attached to some reference sketch geometry, not a plane.

if I understand it correctly, it shouldn't be done because of the topo ... problem

[chrisb]

However in this case it is attached to some reference sketch geometry, not a plane.

if I understand it correctly, it shouldn't be done because of the topo ... problem

In the opposite, we usually recommend to attach to the main planes or to sketches, see this page, especially the paragraph about creating stable models. Yet attaching to sketches can cause toponaming issues.

[run_the_race]

However in this case it is attached to some reference sketch geometry, not a plane.

if I understand it correctly, it shouldn't be done because of the topo ... problem

In the opposite, we usually recommend to attach to the main planes or to sketches, see this page, especially the paragraph about creating stable models. Yet attaching to sketches can cause toponaming issues.

I have read that very good advice and tried to apply it. I thought I was applying the concept of a use a "master sketch", so then I thought its okay to attach a datum to a "master sketch", you reckon rather not?

[chrisb]

I have read that very good advice and tried to apply it. I thought I was applying the concept of a use a "master sketch", so then I thought its okay to attach a datum to a "master sketch", you reckon rather not?

You did it right by attaching to the sketch! I think thoma-niemann got it wrong. He may had thought about attaching to faces instead of sketches.