Hi Dan, also what radius are you attempting to fillet your original model with?

That model is already at a small size, so only a pretty darn small fillet radius will actually fit in the space that is available there. You may be trying to use too large of a radius than will physically fit in that area.

Here is what it looks like over here loading your model, selecting the entire object and then running Fillet with a radius of 0.01 units:



Sometimes you may be surprised at how much space fillets will actually take up, when you run into filleting problems one of the first things you can try is to try a much smaller radius, like 1/10 or even 1/100 of the value you were previously trying with and see what that does.

- Michael