projecting curves

I am trying to project a helix onto the face of a cylinder. I have done it before but I forgot how.

Bob

Reply to
<castlebravo242
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We have to ask why?

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Reply to
manager

To model threads on a wood screw.

Bob

Reply to
<castlebravo242

I got it to work but the results are quite ugly. the sweep cut or bossbass on a projected helix is quite ugly. It has to be done with helixes made from circles to look decent.

Bob

Reply to
<castlebravo242

If you project a helix onto the surface of a cylinder then it is no longer a helix but just a projection. As such there is some approximation going on because of that process. That approximation may make the result somewhat jagged.

If you are making a thread on a wood screw a cylindrical helix or even a tapered helix may not work. In that case you may need to make a curve by defining points and using them to define your curve.

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Reply to
Paul B. Kellner

If you want to add a thread to a non-cylindrical face, try it this way:

  1. Make a helix that is larger than the largest diameter of your shank
  2. Make a surface sweep of a straight line from your helix, such that the straight line points straight toward the center of the shank. The end result looks like an auger.
  3. Use the intersection of the auger surface and the shank as a guide for your thread section sweep.

When you make your thread section, be sure the section has positive penetration into the shank surface. If you go line-to-line, there may be zero-thickness issues when generating your thread.

I used a similar method for creating a barrel-shaped spring. See spring model in "hinge.zip" at

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Reply to
That70sTick

I used 3 merge helixes for the path. I had to make two one for each cutter shape.

Bob

Reply to
<castlebravo242

Is it possible to force a sweep with a self intersecting profile? I think Inventor will do it with a warning.

Bob

Reply to
<castlebravo242

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