Bspline and sketch problems

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martin.proks
Posts: 3
Joined: Sun May 13, 2018 7:46 am
Location: Czech Republic

Bspline and sketch problems

Postby martin.proks » Mon May 14, 2018 11:50 pm

Hello,

I'm just newbie in the FreeCAD, I'm playing with it the second evening. I'm trying to create little unconventional wing for RC model "UFO" style for 3D print technology. But I have some problems:

1) B-Spline problem. It looks that the B-Spline works just with small amount of points. If the amount of points is bigger than some number, the spline start doing unexpected things. See the file spline-problem.png. The airfoil was imported from file of points and it made DWire - flat surface bounded by lines based on the points. Then it was converted in Draft workbench to the B-Spline and changed to open spline. See the b-spline-problem.fcstd and spline-problem.png. When I tried another way, degrade the DWire airfoil to the points and create the B-Spline manually, it looks that FreeCAD B-Spline works well to some number of points. Am I right, or am I missing something - doing something wrong?

2) Sketch problem. When am I working on a geometry and there is more objects, the sketch creation makes problems. It looks to me that the sketches are created randomly inside the feature tree. I have active some feature or node (or how does it called in FreeCAD), but the sketch is created somewhere elsewhere. I have to seek where was the sketch created and then move it where I want to have it. It is quit annoying. Am I doing something wrong or is it a bug? See the file wing.fcstd and try to make new sketch in Part Design.

Thanks for answer

FreeCAD 0.17
Revision 13522 (Git)
Ubuntu 16.04.4 LTS
Attachments
wing.fcstd
(750.75 KiB) Downloaded 6 times
b-spline-problem.fcstd
(18.48 KiB) Downloaded 4 times
spline-problem.png
spline-problem.png (15.05 KiB) Viewed 75 times
Martin Prokš
martin (dot) proks (plus) freecad (at) gmail (dot) com
chrisb
Posts: 14104
Joined: Tue Mar 17, 2015 9:14 am

Re: Bspline and sketch problems

Postby chrisb » Tue May 15, 2018 5:19 am

martin.proks wrote:
Mon May 14, 2018 11:50 pm
2) Sketch problem. When am I working on a geometry and there is more objects, the sketch creation makes problems. It looks to me that the sketches are created randomly inside the feature tree. I have active some feature or node (or how does it called in FreeCAD), but the sketch is created somewhere elsewhere. I have to seek where was the sketch created and then move it where I want to have it. It is quit annoying. Am I doing something wrong or is it a bug? See the file wing.fcstd and try to make new sketch in Part Design.
I sort of can confirm the issue here, but at a second look it seems to be ok: There is exactly one body now in your model, "Wing spar" and the sketch is correctly inserted there. It might seem random only because you have buried the body deep in the Part tree.
If you want it at top level, create a new body first.