(Solved) Octagon Fail

[Sam]

Code: Select all

OS: Ubuntu 16.04.3 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.11779 (Git)
Build type: None
Branch: master
Hash: 7c87549e4ba992cf324c59986908a22ccb5fcf4c
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: English/UnitedKingdom (en_GB)

Start FreeCAD
New document
Part Design WB
New sketch on XY plane
(Auto constraints on)
Create Octagon
Centre on origin
Radius on horizontal axis; x > 0 y = 0

The octagon is created with zero size. Trying to set the radius of the circumscribing circle is not allowed; conflicting constraints.

Thoughts?

[bejant]

Thoughts?

To Constrain the radius of the blue construction circle that is created after you make the octagon:
Select the blue circle,
Click the Radius Constraint:

and follow the prompts...

[Sam]

I mustn't have been clear. I have worked around the issue. No worries. I am reporting unexpected behaviour.

Creating the octagon in the specific way I described caused an octagon of zero size. Therefore the construction circle is not visible. Finding and editing the constraint via the constraints dialog in the tasks tab fails due to conflicting constraints.

[wmayer]

From a mathematical point of view it's not a bug because the sketch fulfills all constraints. However, from a user point of view one of course doesn't want to have a circle with a radius of 0.

In the past we had a similar issue #0000909 where when creating a circle in origin and the rim point on an axis then the tangency constraint forced the circle to degenerate to a point.

So, I think we should also implement a workaround to avoid to degenerate the circle.

Feel free to open a bug report.

[Sam]

Feel free to open a bug report.

I just played about some more, and it seems to only happen when the suggested constraints are point on object, and horizontal.

Issue issue #3160 created. But, balls: It's duplicate of issue #3154.

Sorry for the noise.

[Kunda1]

closed issue #3160 in a favor of issue #3154

[abdullah]

https://github.com/FreeCAD/FreeCAD/pull/1141

[meme2704]

Do not panic, this is not the work of the wicked weevil, it also happens in V0.16, it combines the constraints of the center with those of the starting point of the circle or the poligon
Solution: with the capture window grabbed this common point, and gives 1 radius

[Kunda1]

git commit 2e1d219377720bb2

[Sam]

Thread title updated