Hi LM, I think there's some kind of other bug coming into play with that particular model though.

I've attached a version that I made using Shell and it can do the partial chamfers ok.

- Michael

Michael, thanks for taking a look. I was able to do a small chamfer on the whole object like you did.

I also tried another object that to my human eyes looks kind of similar.



And I can chamfer just the front edges.



I know that to my eyes the shapes look kind of similar, but they must be quite different mathematically. Are there any suggestions for what to avoid if you want to later chamfer something? "Stick with only straight edges" isn't it, because I've done lots of fillets on curves. "Only planar surfaces that join each other" isn't it either, because this model shows chamfers on curved surfaces and edges.

Weird. I tried your model too and it works for me as well (the partial chamfer).

Then I took my first model, deleted the interior surfaces and recreated them using the Shell command, and then I could chamfer it in the way I first wanted to as well.

Do you know what the difference is between those two? My original model, and one recreated with Shell? Visually they look pretty much like the same thing.

In my original model, I created a sphere, used Shell on it, then boolean subtracted I think three other spheres.

Hi LM,

re:
> Do you know what the difference is between those two? My original model, and one recreated with Shell?
> Visually they look pretty much like the same thing.

Well in the shell model the "side walls" are basically a loft while in the original they were trimmed pieces of spheres.

I'm not exactly sure yet why your original version won't work, but it seems to be failing to trace out the fillet rails properly.

It seems to be a bug when processing these particular surfaces. I tried with making 1.1 times larger sphere cuts and that one worked ok too.

So I don't think it's illustrative of some kind of general case that you would try to avoid.

Also if you run ShrinkTrimmedSrf on your original object it will do the partial chamfer ok too. Select the object, type the Tab key and then type ShrinkTrimmedSrf and push Enter. That makes the underlying surfaces of the side walls to be smaller pieces of a sphere instead of being full spheres.

If you run into fillet troubles it can be worth a try to run both Merge and ShrinkTrimmedSrf on the object and try again.

- Michael