Why is this sketch not closed

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!
chrisb
Posts: 24414
Joined: Tue Mar 17, 2015 9:14 am

Re: Why is this sketch not closed

Postby chrisb » Tue Mar 17, 2020 8:41 am

Forthman wrote:
Tue Mar 17, 2020 8:21 am
The sketch seems to be attached on something
if i set "Map Mode" to "desactivated" it's ok :idea:
I guess this recomputes the sketch as well, so that may be the reason for the fix.
openBrain
Posts: 3984
Joined: Fri Nov 09, 2018 5:38 pm

Re: Why is this sketch not closed

Postby openBrain » Tue Mar 17, 2020 9:41 am

chrisb wrote:
Tue Mar 17, 2020 12:08 am
DogLeg recomputes here without leavong open vertices, Levenberg-Marquardt leaves it open at some tangents. I remember topics talking about this. LM solver should be used with great care.
I definitely mistook here and LM solver definitely is the reason. Thanks for overwatching @chrisb. ;)
chrisb
Posts: 24414
Joined: Tue Mar 17, 2015 9:14 am

Re: Why is this sketch not closed

Postby chrisb » Tue Mar 17, 2020 10:53 am

openBrain wrote:
Tue Mar 17, 2020 9:41 am
I definitely mistook here and LM solver definitely is the reason.
The sketch is rather simple, so without a faint memory of the issues I wouldn't have guessed that it could be the solver.
insomniux
Posts: 13
Joined: Fri Aug 02, 2019 3:19 pm
Location: Netherlands

Re: Why is this sketch not closed

Postby insomniux » Tue Mar 17, 2020 7:49 pm

Thanks to all who responded. All are right. Sometimes only recalculating helps, removing the attachment of the sketch helps, etc. I've done some comparison between FC versions and the different solvers. I can confirm chrisb's analysis. When I use DogLeg the sketch is valid and makes a valid pad, when I use LM the curve is not closing well and yields an invalid sketch for padding. I've confirmed this by switching several times between the two solver algorithms.
Thanks again for your input!
Mike
chrisb
Posts: 24414
Joined: Tue Mar 17, 2015 9:14 am

Re: Why is this sketch not closed

Postby chrisb » Fri Mar 20, 2020 1:25 pm

Here is a simplified version of the sketch. It can be padded after solving with DogLeg, and cannot be padded after solving with Levenberg-Marquardt. I will add this to issue #3658.
Snip macro screenshot-0bd2ed.png
Snip macro screenshot-0bd2ed.png (5.13 KiB) Viewed 50 times
Attachments
LMvsDogLeg.FCStd
(5.89 KiB) Downloaded 4 times