Hello, I have been having some difficulty extruding a profile along 2 rails. I have used various extensions and just cannot seem to get it correct. If you have any info on how to do it properly that would be appreciated. I will attach file with this post!
Extrusion Help.skp (392.2 KB)
One way to do it.
First, scale it up by a factor of 100 or 1000 to avoid the tiny faces issue. Since the shape is symmetrical left to right and front to back, just extrude a quarter of it. Then copy and flip the resulting extrusions to make the whole. I delete the short edge between the rails just for clarity. Do not plan to use the faces in the extrusion setps. You’l also need to adjust the profile curve on the one midway along the long side so its shape is correct and the ends meet the rails.
Extrude Edges by Rails (TIG’s Extrusion Tools) results in this for the first step. Do not delete the original curves at this point.
Add in the edges for the top. Divide them into two segments and weld them so they become curves. Then run Extrude Edges be Rails on those to get that surface.
Use Flip/Copy to make the other quadrants.
By the way, you could do this in halves instead of quarters but the extension will have to create twice as much geometry in each step so you’ll just have to wait longer.
Screenshot 2026-05-20 at 4.18.54 PM2874×1758 162 KB
Thanks for responding so fast! I followed what you said to the best of my ability and ended up with something like this… Is there anything you notice that I may have done wrong? I scaled it up by a factor of 1000, redrew the profile curve to hit the rail, etc. Also, if you have a recommendation of a better method to do this overall, please let me know. Thanks!
I think Extrude Edges by Rails is the best way. Did you weld all the curves?
I believe so, I am welding all edges. Is welding curves different?
I will try doing it in halves. Did you just copy the same profile over and flip?
Yeah I used the same one.
It wouldn’t hurt to use fewer segments in your rails. That would speed things up.
It looks like you did the same thing I did. I also did it by using the curves at the ends as the rails and the long curves as the first and last selected curves. I’m not sure why you are getting different results. Maybe @TIG would have some insight. It’s late for him now though.
Thank you for the help! I have still been trying to play around with it. Hopefully @TIG can provide some more guidance.
Extrusion in SketchUp using TIG Extrude Tools extension and Fredo Spline.
Full quads, good flow, proper amount of geometry.
Finally got it to work, I selected them in opposite order like you described! Thanks for the help.
Thank you very much for the help!
