Another Fillet Issue

I need to run a 0.250" fillet around the edge highlighted in the attached file. None of the filleting tools I’ve tried will work, which perhaps isn’t surprising given the geometry (be nice if they did though). Before I blunder on manually creating the filet I thought I’d see how the Rhino Gurus on the forum would tackle this situation. Any advice offered is much appreciated.

Cheers.Fillet Problem.3dm (268.1 KB)

Hello MisterB
This is the best I could do. Couldn’t do it using fillet though.Fillet Problem-sol.3dm (442.5 KB)

Thanks very much, Tony. That’s a good solution, although I may need to keep the radius a little closer to 0.250". I’d be interested to know what your work flow was, perhaps I can adapt it to adjust the radius.

Again, thanks very much for taking the time to help. It’s much appreciated.

Cheers, MisterB.

Not much of a workflow. Just Pipe to trim out the unwanted stuff and sweep 2 rail (chain edges). Added a couple of extra curves near the bends (blend curve) to keep things smooth. I should add that I left the pipe in the file on default layer.

Thanks again, Tony. I guessed that may be the way you approached it; that’s how I would usually tackle it too (although I missed the pipe on the default layer). I hoped there might be a very clever way to do it that I hadn’t encountered before, perhaps there is. In the meantime I’ll give the pipe method a go, not having the radius bang on 0.250" really shouldn’t be an issue (inside of a casting).

Cheers, MisterB

If I were doing this I would avoid using all fillets of exactly the same size. Having the .25 fillets wrap around slightly larger fillets in the corners avoids the 3 sided surfaces in the corners and makes
the geometry more bullet proof for exporting to other Cad or Cam systems.

In this example I used a combination of .26 and .25 fillets and made all the fillets with the filletSrf command. The difference in actual shape between a .25 and .26 fillet in this example is less than your absolute tolerance.
Fillet ProblemX.3dm (288.3 KB)

Thanks, Jim. Your method gives very similar results to the solution Fusion 360 gives me (I just downloaded it to try and it’s done this fillet and several others in about 30 seconds). I hope V6 brings some much needed improvements.

Thanks again for taking the time to help, its much appreciated.

Cheers, Misterb