How to project a curve onto a cylindrical surface?

[freecad-heini-1]

Hello,
which possibilities are there in Freecad to project a closed Reflect-Lines (curves-workbench) onto an outer cylindrical surface?
In this way, I was able to create very good parting surfaces in Creo for tool- and mould making. The reflect lines and the projection curve of the cylinder surface have to be connected afterwards only by loft.
Who knows a trick how to project onto a cylindrical surface?
A scaled clone doesn't quite return the result I'm looking for.
Many greetings
Wilfried

project_reflect-lines_to_cylinder-face.png (33.75 KiB) Viewed 2489 times

project_to_cylindrical_face.FCStd

(202.64 KiB) Downloaded 89 times

[microelly2]

there is no default method but it is simple to map the coordinates of some discretized points of the curve to cylindric coordinates and than normalize the radius.
I will look for the script, I'm sure I had it already.

[saso]

Maybe not exactly what you need but it does give you quite a lot of room to play with the parameters and get different results out of it...

Note:
- I have not made the final loft surface between the section and the reflectlines
- I have scaled the clone only in X an Z directions (not Y)
- with the scale and placement properties of the clone one can get a lot of flexibility on the shape of the section curve
- this is just a quick test of the first idea I had and so I did not check if it is fully parametric or search for ways to make it

[microelly2]

Maybe not exactly what you need but it does give you quite a lot of room to play with the parameters and get different results out of it...

Note:
- I have not made the final loft surface between the section and the reflectlines
- I have scaled the clone only in X an Z directions (not Y)
- with the scale and placement properties of the clone one can get a lot of flexibility on the section curve
- I did not check if it is fully parametric or search for ways to make it

It's an intersting solution.
Here my method

Code: Select all

import numpy as np

s=App.activeDocument().ReflectLines001.Shape

eds=[]
for e in s.Edges:
    pts2=[]
    pts=e.discretize(100)
    for p in pts:
        h=p.y
        arc=np.arctan2(p.x,p.z)
        r=FreeCAD.Vector(p.x,p.z).Length
        R=150
        p2=FreeCAD.Vector(np.sin(arc)*R,h,np.cos(arc)*R)
        pts2 += [p2]

    Part.show(Part.makePolygon(pts2))

The results are the same

[saso]

The results are the same

Yes, it was also my first curious idea to check (compare) that after I generated yours

[microelly2]

I still have a little bit to fight with the self connecting cylinder face but this is a use case of uv projection from pyflow too.
the same result.

cp_019.png (141.53 KiB) Viewed 2441 times

[freecad-heini-1]

I still have a little bit to fight with the self connecting cylinder face but this is a use case of uv projection from pyflow too.
the same result.
cp_019.png

Hi Thomas,
that looks good. Many thanks to you and Saso for the help. Please upload your Freecad file, because I want to create the loft face to be able to judge it.
Many greetings
Wilfried

[freecad-heini-1]

- I have scaled the clone only in X an Z directions (not Y)

This gives a very useful result.
If you want an angle of attack to center the two halves of the mould to each other, you can also scale the other axis. Thank you.

[hammax]

… a solution with the means of PartWB and slice:

ProJCurve.PNG (40.85 KiB) Viewed 2413 times

[kisolre]

This gives a very useful result.

But he probably had to downgrade your original ReflectLines because they had overlapping edges and simply cloning and lofting gives wrong result. Are those overlapping lines supposed to be there?