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Tangency flipping on sweep profiles...
dave_franchino
Member Posts: 63 ✭✭
Help Modeling Pipe with Clocked Bends in Onshape
Hey folks,
I'm hoping someone can help me troubleshoot a problem I'm running into while trying to model a parametric pipe system in Onshape. Ultimately, I'd like to create a custom piping tool using FeatureScript, but I'm starting by manually building the geometry in a Part Studio—and I’m already hitting some snags that make me think this will be trickier than expected.
Here’s a video showing the issue (linked below), and I’ll do my best to describe it here: https://youtu.be/5n34GXwETfY
What I'm Trying to Do
The concept is simple: a pipe composed of straight segments and fixed-radius bends. All pipe diameters and bend radii are constant for now.
- The pipe begins with a straight segment L0.
- At the end of L0, there is a bend with angle B1, followed by another straight segment L1.
- At the end of L1, I begin the next segment. This involves:
- A bend B2
- A clocking angle C2 to rotate the bend around the previous straight segment (L1)
- A new sketch plane based on that clocking angle
This process repeats: each segment consists of a bend (with a clocking angle) followed by a straight section. I'm driving all of this with a variable table.
The Problem
Everything works fine within certain ranges of angles. But when I change the bend angle or clocking angle, things start to break down. Specifically:
- The tangency on the bend segment often reverses unexpectedly
- I suspect the normal vector of the sketch plane flips, causing the arc I use for the bend to flip directions
This behavior makes the model unstable and unpredictable, which obviously wouldn’t work for a scripted solution down the line.
What I’m Looking For
- Is there a better way to handle this kind of construction in Onshape?
- Is there a known trick for stabilizing sketch plane orientation when chaining arcs and rotations like this?
- Would FeatureScript help avoid this kind of instability, or would I just run into the same reversal issues?
I’d love to hear any suggestions or strategies. I'm decent with Onshape modeling but still pretty green with FeatureScript—any guidance would be greatly appreciated!
Thanks!
—Dave