Does anyone know how to make a precise curved polar slot in a cylinder? All solutions I have tried in Blender do not have a constant width.

And should be theoretically possible to mill on a turn milling machine! I do not want a cad but I would like it to be as realistic as possible, as I later want to animate a pin that is gliding through the slot.

enter image description here

  1. Create the mantle of the cylinder, with simple polygons

  2. Add thickness to it

  3. Add a remesh modifier with a resolution, which is good enough for you (7-8) and apply it

  4. Make your mesh flat again. Delete the extra faces in edit mode, stet only the upper surface.

  5. Rotate the mesh to vertical pose

  6. Set the origin to the geometry

  7. Add a Simple deform modifier, with 360° bending and apply it

  8. Remove duouble verts.

  9. Add a solidify modifier.

Check out this: Polar slot in cylinder with Blender

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    $\begingroup$ I marked this answer for now because I think it is most precise answer. Even thou I did not write it explicit in the question (sorry my fault) but this part is theoretically not possible on a turnmilling machine. On a turnmilling machine the two sides of the slot would not be concentric but parallel (Imagin a milling bit milling the slot). I know it is knit picking but I would be very glad if you have an idea how I could realize that. Later I would like to animate a zylinder that is gliding through the slot. I also have to say that I am very Impressed with your creativity in using blender!! $\endgroup$ – josh schmidt Feb 24 at 20:30

1.pic: Make a cylinder like this (hit Ctrl+R to make edge loops)

2.pic: Turn on proportional editing (sphere), select the marked verts and move them apart with scaling "s key" use the mouse scroll to adjust ray of the proportional editing.

3.pic: Switch to smooth the proportional editing, select the marked faces and rotate them around the z axis R key and then Z key.

4.pic: Go to object mode and add a solidify modifier

5.pic: Click on smooth shading, turn on auto smooth and adjust it

6.pic: If you go to edit mode, select all faces by A key then hit Ctrl+T to triangulate the faces the surface will be smoother, but the topology will be worse.

enter image description here

  • $\begingroup$ Thanks that's a very interesting approach. But the problem for me is that the groove does not have constant width. The Width decreases at the bend. $\endgroup$ – josh schmidt Feb 18 at 15:41

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