Making a guide for cutting irregular shoulder on a chair leg


I would like to recreate the cylinder pictured on the left such that the angled slice in the cylinder follows the same path as pictured on the inner wall, but cuts through the cylinder thickness perpendicular to its center axis.

Put another way, I’m making a chair leg with an irregular shoulder- I am roughing it out on a lathe before hand paring the complex angle. I am printing a jig to help not only scribe the line but route up to it closer, thus I need the approximate angle of the shoulder, cut, but not the angle of the shoulder wall. I will then use the cylinder pictured on the left to pare the wall.

Please let me know if this makes sense, its a strange operation to attempt to describe with language.

…or maybe its just Monday.


paring_guide.3dm (3.7 MB)

Hello - Something like this?


Exactly like that in fact. How did you do that Pascal?

And thank you!

Hi Revel -

ExtractSrf these surfaces:

Untrim the outer ones:


DupEdge & Pull these edges to the untrimmed surfaces:

Join all the curves into two closed loops, and Loft between them - I used the Rebuild option to 32 points.


Awesome as always. Missed this forum!

the lofted surface has the right geometry but is an open surface and thus is not able to trim the outer walls of the cylinder. I’ve tried the limited techniques I have for making it a closed surface to no avail.

paring_guide copy.3dm (3.8 MB)

Hi Revel - ExtendSrf the outer edge - (Type=Smooth, Merge=Yes) through the cylinder a short distance, then use that surface and the cylinder surfaces to trim one another - all in one go - and then Join.


very cool. SO I end up with a closed polysrf even though one of those surfaces is open… works for me, thanks again, Pascal