Sketch rotating problem

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klosiu
Posts: 3
Joined: Tue Nov 13, 2018 8:18 am

Sketch rotating problem

Postby klosiu » Tue Nov 13, 2018 9:02 am

Hello all!
Recently I started playing with FreeCAD. I tried some tutorials, made few my own models. From time to time it crashes, but I learned to save often, so it's not a big problem. Especially, that I use it for amateur, hobby things.
However, yesterday I faced a problem, that I can't cope with.
Problematic file is attached.
Now, I want to rebuild some part of "szkielet" sketch, so I double click it to enter edit mode. For some reasons, FreeCAD crashes at this step. Sometimes, but very rarely. When I enter edit mode, I want to delete constraints 107 and 108. When I do that, whole drawing tips over. I found out, that's because of constraint to external sketch "otwory" which, for some reason, changes angle to 180 degrees when I remove constraints in another sketch.
What is a reason for that behaviour? Is it wrong to edit sketch after other operations were made (like pad, or pocket)? Maybe I shouldn't attach "otwory" to pad face, which was made from another sketch depending on "otwory"?
Also, is pad supposed to update itself, when I alter sketch it is based on? I added an arc - element 56 in a sketch "szkielet", but as you can see in a file, part based on this sketch didn't reflect the altered sketch.

I use Part Design and Sketcher workbenches only.

This file was originally created in dev version 0.18.15188 on windows 10 x64. Reason for using unstable version is that, I had a similar problem in 0.17, and I wanted to try dev builds, as I thought, that there may be a bug, that's already fixed. I also tried that on another pc with windows 7 x64, with the same results.
Attachments
prowadnica.FCStd
(192.06 KiB) Downloaded 10 times
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HarryGeier
Posts: 1167
Joined: Mon Jul 10, 2017 12:36 pm
Location: Hof Germany

Re: Sketch rotating problem

Postby HarryGeier » Tue Nov 13, 2018 11:29 am

Hi,

you have strange relationships , in fact not possible relation in the model.

If you look
2018-11-13 12_26_16-FreeCAD.png
2018-11-13 12_26_16-FreeCAD.png (53.26 KiB) Viewed 178 times
you can see there are red dependencies that make it totally instable.

I would recommend study the concept of using a MASTER Sketch and rework it accordingly.

Also... some improvements to consider:

5 Circles = 1 constrained with radius/diam and 4 EQUAL ..
similar with the lots of 1 mm lines...
Kaum macht man´s richtig , gehts´s
My Video Tutorials on Youtube: https://www.youtube.com/channel/UCoe3B ... p8Q/videos
My FreeCAD Stuff on Hidrive: https://my.hidrive.com/share/qr3l1yddy6#$/
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klosiu
Posts: 3
Joined: Tue Nov 13, 2018 8:18 am

Re: Sketch rotating problem

Postby klosiu » Tue Nov 13, 2018 12:00 pm

I started with installing graphviz, so I can monitor dependencies.
Then I removed CYlinder, Cone , Pocket and detached otwory sketch from Pad's face.
I understand how szkielet depends on otwory, and Pad depends on szkielet. However, I don't know why otwory still depends on Pad, and why szkielet points to itself.
1.png
1.png (48.17 KiB) Viewed 168 times
As of master sketch, otwory was supposed to be one, and szkielet was drawn around it. I then took shortcut, and reuse otwory, to make actual holes. I will redraw it of course. Thanks!
Also, thank you for tip about using equal constrain.

Edit:
I guess I figured it out. It was a real mess. Once again, thank you.
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HarryGeier
Posts: 1167
Joined: Mon Jul 10, 2017 12:36 pm
Location: Hof Germany

Re: Sketch rotating problem

Postby HarryGeier » Tue Nov 13, 2018 1:10 pm

Fine that you solved your problem,

a MASTER Sketch should only contain geometry that is NOT used to create a feature directly. For all feature sketches you should use references to the master sketch . Look at my videos, where i use master sketches in a variety of ways..

Her i add a simple example file showing 2 ways how to use a master sketch.. I might extend that somehow later or make a video espcially on the different ways of referencing the master sketch
2018-11-13 14_23_36-FreeCAD 0.18.png
2018-11-13 14_23_36-FreeCAD 0.18.png (131.44 KiB) Viewed 150 times
Attachments
demo_mastersketch.FCStd
(16.67 KiB) Downloaded 10 times
Kaum macht man´s richtig , gehts´s
My Video Tutorials on Youtube: https://www.youtube.com/channel/UCoe3B ... p8Q/videos
My FreeCAD Stuff on Hidrive: https://my.hidrive.com/share/qr3l1yddy6#$/
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miniellipse
Posts: 73
Joined: Tue Apr 24, 2018 9:09 pm

Re: Sketch rotating problem

Postby miniellipse » Tue Nov 13, 2018 9:42 pm

HarryGeier wrote:
Tue Nov 13, 2018 1:10 pm
I might extend that somehow later or make a video espcially on the different ways of referencing the master sketch
2018-11-13 14_23_36-FreeCAD 0.18.png
That would be nice. Thanks in advance.