Good evening all,

I can't seem to get MOI to fillet the yellow highlighted angles. I realize that they're pretty sharp in places, but I'm just trying to add in a slight fillet in order to soften the edges. I'm not sure what I'm doing wrong. Any pointers or ideas? When I try to fillet, even using values of 0.2 and similar, the program says its working on it, but then does nothing. I've tried restarting the program to no avail so I suspect its something with the model itself.

Yes, its a Star Trek saucer, for a very early Federation design.

Many thanks,

Bob

Hi Bob, so there are a couple of different things going on. One thing is it's rather difficult to fillet some of these kinds of juncture areas where multiple fillets are coming together at a common vertex but also I noticed that when I broke off those faces I was able to do some fillets that were not working on your full model.

So I examined the model and I found a couple of spots with degenerate faces in them, meaning faces that have all their surface areas trimmed away so that they are more like a line rather than a face with surface area. Those can mess up some kinds of traversal algorithms.

Those faces were in these areas:


I've attached a version of the model with those faces removed and now you can get some fillets done on some individual edges which can then make it easier to do some some other ones.

What I mean is put in a larger radius fillet here for example:



Then you can put in a little bit smaller radius fillet here:



And now with those areas smoothed out it will be easier to do an even smaller radius along here:





Fillets are generally easier to calculate along edges that are smooth to each other so some of the juncture areas can get easier to process when they are smoothed out with a larger radius first.

In other cases it can be better to do the fillets all at once and also do all edges coming out from a single vertex instead of only some of them but here you've got some difficult to handle junctures.

Another thing that might simplify things for fillet could be to cut off pointy spots something like this:








- Michael

You are awesome, thank you.

I'm just still unsure how those degenerate faces came to be. That's one of the things that I still find mystifying, both in MOI and a solid modeler like Alibre. For the Baton Rouge saucer, the big chunky part was made from a solid and then Booleaned down to shape. To make matters odder, MOI originally wanted to fillet the edges. But, I had to knock off work for the night so I undid the fillets and saved the file, wanting to do more work on the model the next day and reconsider the fillet radii. That next day is when, after opening the saved file, it wouldn't fillet. Again, odd as all I did was save the file with no other changes.

Oh well, no worries. You are the best and I thank you.

Robert