(Solved) Octagon Fail

Post here for help on using FreeCAD's graphical user interface (GUI).
Forum rules
and Helpful information
IMPORTANT: Please click here and read this first, before asking for help

Also, be nice to others! Read the FreeCAD code of conduct!
User avatar
Sam
Posts: 171
Joined: Sun Mar 20, 2016 6:19 pm

(Solved) Octagon Fail

Postby Sam » Mon Aug 14, 2017 11:23 pm

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?
Last edited by Sam on Thu Dec 07, 2017 9:21 pm, edited 1 time in total.
User avatar
bejant
Posts: 5933
Joined: Thu Jul 11, 2013 3:06 pm

Re: Octagon Fail

Postby bejant » Tue Aug 15, 2017 3:02 am

Sam wrote:
Mon Aug 14, 2017 11:23 pm
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:
Image
and follow the prompts...
User avatar
Sam
Posts: 171
Joined: Sun Mar 20, 2016 6:19 pm

Re: Octagon Fail

Postby Sam » Tue Aug 15, 2017 3:23 am

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
Site Admin
Posts: 14882
Joined: Thu Feb 19, 2009 10:32 am

Re: Octagon Fail

Postby wmayer » Tue Aug 15, 2017 7:57 am

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.
User avatar
Sam
Posts: 171
Joined: Sun Mar 20, 2016 6:19 pm

Re: Octagon Fail

Postby Sam » Tue Aug 15, 2017 9:36 am

wmayer wrote:
Tue Aug 15, 2017 7:57 am
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.
User avatar
Kunda1
Posts: 5761
Joined: Thu Jan 05, 2017 9:03 pm

Re: Octagon Fail

Postby Kunda1 » Fri Aug 18, 2017 10:42 am

closed issue #3160 in a favor of issue #3154
Want to contribute back to FC? Checkout:
#lowhangingfruit | Use the Source, Luke. | How to Help FreeCAD | How to report FC bugs and features
abdullah
Posts: 3174
Joined: Sun May 04, 2014 3:16 pm

Re: Octagon Fail

Postby abdullah » Wed Dec 06, 2017 3:49 pm

User avatar
meme2704
Posts: 2926
Joined: Sat Apr 01, 2017 2:47 pm
Location: Vosges

Re: Octagon Fail

Postby meme2704 » Wed Dec 06, 2017 6:35 pm

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
User avatar
Kunda1
Posts: 5761
Joined: Thu Jan 05, 2017 9:03 pm

Re: Octagon Fail

Postby Kunda1 » Thu Dec 07, 2017 7:10 pm

Want to contribute back to FC? Checkout:
#lowhangingfruit | Use the Source, Luke. | How to Help FreeCAD | How to report FC bugs and features
User avatar
Sam
Posts: 171
Joined: Sun Mar 20, 2016 6:19 pm

Re: (Solved) Octagon Fail

Postby Sam » Thu Dec 07, 2017 9:21 pm

Thread title updated