Rotational object issues

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anno
Posts: 26
Joined: Sat Jun 13, 2020 7:15 pm

Rotational object issues

Post by anno »

Hi,

I have created a easy rotational object with b-splines but I have some issues with it.
  • Why is not possible to revert 1 drawn? If i use CTRL+Z in sketch, the whole B-Spline is reverted?
  • If I want to close the drawing I get an constraint error (attachment image 1-3 in the zip archive) but If I do a revert with CTRL+Z the constraint error disappears. I think it is right because I only want to close the sketch but not the first display of the constraint error.
  • If I select my object with double-click in the combo view is not entered and the axis are not displayed (almost the same as here https://forum.freecadweb.org/viewtopic.php?f=19&t=56904). It only works with the body cross-sections object. (attacment 4)
  • Last but not least I get some rendering errors after finishing the sktech (attachment 5) on the right hand side. The left hand side looks good.

Freecad:

OS: Ubuntu 20.04.2 LTS (ubuntu:GNOME/ubuntu)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.19.1)
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.8
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.4.0
Locale: English/United States (en_US)
Attachments
cup.FCStd
(34.11 KiB) Downloaded 71 times
5.png
5.png (123.84 KiB) Viewed 3064 times
4.png
4.png (102.15 KiB) Viewed 3064 times
sketch.zip
(763.8 KiB) Downloaded 75 times
chrisb
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Re: Rotational object issues

Post by chrisb »

I have no problem to close the sketch: I select the upper point of the vertical line and the right end of the B-spline and create a coincidence.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
anno
Posts: 26
Joined: Sat Jun 13, 2020 7:15 pm

Re: Rotational object issues

Post by anno »

Well, I have tried it again. For me it only works, if I delete the revolution objekt in the combo view and ceate a new one but not with the existing revolution.
Last edited by anno on Sun Mar 28, 2021 11:31 am, edited 1 time in total.
anno
Posts: 26
Joined: Sat Jun 13, 2020 7:15 pm

Re: Rotational object issues

Post by anno »

One question more:

How can I measure dimensions of b-splines? I can not use measure tools or even draw the dimension in TechDraw workbench because there no anchor points to measure something.
Attachments
TechDraw.png
TechDraw.png (56.89 KiB) Viewed 3033 times
chrisb
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Re: Rotational object issues

Post by chrisb »

anno wrote: Sun Mar 28, 2021 11:19 am How can I measure dimensions of b-splines?
Currently this is not really possible. With additonal sketch geometry you can get the control points.
You can, however, create the curve from several B-splines which are connected appropriately. Then you can measure to the endpoints.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
anno
Posts: 26
Joined: Sat Jun 13, 2020 7:15 pm

Re: Rotational object issues

Post by anno »

I modified the model a little bit and I get the next rendering error.
Attachments
cup2.FCStd
(34.36 KiB) Downloaded 59 times
hidden lines.png
hidden lines.png (23.79 KiB) Viewed 3004 times
chrisb
Veteran
Posts: 53785
Joined: Tue Mar 17, 2015 9:14 am

Re: Rotational object issues

Post by chrisb »

The default export uses the same mesh used to display the object. The defect is to be seen in 3D view as well and vanishes if you set the view property Deviation=0.1 .
Besides that you can alway use a different mesh algorithm in the MeshDesign workbench.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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