Blend Surface Tangency Not Along Edge


I’ve had trouble finding a solution online to a blend surface challenge. I need to find the tangency between two surfaces that are varied in width. One surface is a fixed fillet radius of 1.5" and I need to preserve the radius but trim the length of it to be tangent with the bottom edge. See attached for reference images, and thank you in advance. problem 3

Hmmm - it looks like you are drawing lines from the lower edge to be tangent to isocurves on the fillet - correct? So to my eye, if the line you draw is in plane with the arc/isocurve on the fillet, then you’re doing it in a way which ought to work if you make enough lines…


Hey Pascal,

Yeah, I figured that was the brute force way. I imagined there would be a method to essentially interpolate the blend surface along the U and V coordinates of the original surface, similar to BlendCrv but in 3 dimensions?

Hello - it is probably not too hard to script the brute force way to at least speed things up a little- can you post a file or send it to me via PM? You are looking for a curve on the fillet surface that corresponds to the edge of a tangent ruled surface, correct? If my assumption about the lines being in plane with fillet isocurves is correct then it should be pretty easy (famous last words).

In case anyone is watching, here’s a script that may help in at least some cases. (3.2 KB)

To use the Python script use RunPythonScript, or a macro:

_-RunPythonScript "Full path to py file inside double-quotes"


@nikodellic why you’re starting from the radius and not from the side surface?
for me the fillet tools give you the exact result but from a sharp edge.
if you sweep1R the vertical section and make the fillet it should work and it’s much faster.

In this particular instance, there were too many variables that prevented the fillet edge from working cleanly.

any chanche you can share this part of the drawing?
I’m interested in give it a try.

Hi Skysurfer,

Fortunately Pascal was able to assist me with exactly what I needed. Thanks anyway :slight_smile: