Need a toolpath

Hello,
Haven’t been around since the old newsgroup went away! Been using SolidEdge and now SolidWorks but still use my old Rhino 3 when they choke on 3rd party models. Now I need to create a toolpath for our CNC. The part is a round piece of plastic pipe which I want to spiral mill the bore to size including a groove that is tapered in at the top, out at the bottom. So I am trying to create one curve that will be followed with the end of the tool in engraving mode. My first thought was create the inside surface and intersect it with a surface created by spiraling a line about the center axis for the depth needed. Then use the intersection for the toolpath. Could’nt quite get Rhino to do it. Both of us are getting a bit old! Suggestions?

Does this help? I think it’s a version of what you’ve described.

Best regards,
Doug
toolpath pipe spiral 001.3dm (267.3 KB)

Doug,
any chance you could save this in the Rhino 3 format? I can’t open it. It may be time for an upgrade, my license says 2006!

Gary H. Lucas

Have you read my blog? http://a-little-business.blogspot.com/

Oops, you said you were working in 3.0…
toolpath pipe spiral 001 v3.3dm (355.8 KB)

Doug,
Thanks for your efforts. It wasn’t quite what I was looking for, I needed a spiraling expanding and contracting curve. I did manage to get exactly what I needed. The mistake I was making was not picking roadlike from top when sweeping a line along the helix. Once I did that the intersection of that surface and a cylindrical surface of my part gave me the correct curve.

Hi Doug, I am looking for a circular groove (not a spiral), but inside a tube like this. Can you explain how to make the groove?

Thanks in advance!

Hi CW,

I think one of these is what you mean; either the cross-section of the groove is circular, or the path the groove takes is circular. Regardless, the two examples on the left share one workflow, and the two on the right share a similar, but slightly different workflow.

The two on the left:
Extract Isocurves (one is U, the other is V)
Circle (Around Curve)
Sweep 1 Rail
Boolean Difference

The two on the right:
Draw curve, e.g. straight line, circle
Project Curves (additional projections have been deleted for simplification/clarity)
Circle (Around Curve)
Sweep 1 Rail
Boolean Difference

I hope this answers the question you were asking! If not, let me know and I’ll try again.

Best regards,
Doug

circular grooves.3dm (454.5 KB)