Offset holes in spiral surfaces - won't line up!

I have created a spiral with some holes in it as part of a sculpture. It will be two layers deep, with the holes offset from layer 1 to layer 2. I am having a terrible time getting the holes to line up - I have squished, unrolled, silhouetted the surfaces and applied the curves to the second surface, offset the holes by 1". Can’t get them to be concentric from one layer to the next. Can you help? I’m happy to send you my file for review. THANKS!

This is Rhino for Mac

Would it work if you created the 2 layers without holes, then created a bunch of cylinders which extended through both layers and used them to split the layers?

Don’t think so, if I understand your suggestion. The holes are of different shapes (square, squiggle, crescent, etc.) and reduced in size from layer one to layer two. The problem is that I can’t get the squished or unrolled surfaces to line up, so when I squishback they’re way off-kilter.


SPIRAL_020817-email.3dm (4.89 MB)

Hi Bill - try - DupBorder on the already trimmed surface and then Pull the resulting curves to the other surfaces. Use the results to TrimorSplit` the holes in the offset surfaces.



Are you flowing the geometric shape curves onto the outer spiral surface to create your cutouts?

Brian’s idea worked perfectly to offset the holes from layer to layer, but now the problem is offsetting the holes, reducing by 1" or so in the second surface.

OSTexo, I squished the surface, created the hole curves, then squished back to loft then trimmed the holes.

I appreciate everyone’s help!

Hi Bill - OffsetCrvOnSrf may help, but you may need to do some cleanup to get the curves you like.

Who’s Brian?? =)



Perhaps flowing the curves along the inner and outer surfaces and then lofting would provide a better result, but you’d need to work in reverse for a few steps to minimize distortion of the trimmed areas to layout your base surfaces. Does that make sense?

The guy in “The Life of …” ??

Yes, flowing geometric shape curves.

Brian is Brian James, with Robert McNeel. - But he didn’t include the TrimorSplit, which I’m going to try now, thank you!

Of course! No wonder he’s not in this thread!



Conceptually is this what you’re looking for?

Spiral.3dm (1.1 MB)

Sure is! I was pretty close, then realized my layers were too far apart, and the graphics I used on the DupBorder was wrong because I changed the distance, so sorta starting again.

Thanks for following up!

All set, everything worked, thanks a million everyone!