Hi ello - yeah it's not going to be good for filleting to have areas like this where your side surfaces get all narrow and collapse down to a point:



Fillet doesn't know how to cross over edges from other surfaces than the ones that are directly joined to the edges being filleted, so basically it is limited to have to be smaller than this edge here:




It would help a lot to make a more simple and regular topology to your surfaces rather than having them come to that "pole" collapsing point at the tips.


Did you see some of the other strategies that I mentioned previously:

http://moi3d.com/forum/index.php?webtag=MOI&msg=1002.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=3137.1

Those would probably give you a topology with a better shot at filleting.


What radius of fillet are you trying to create? It might be possible to get some fillets on your existing shape here using the lower level surface/surface fillet. That can be applied if you break your model into individual surfaces using Edit > Separate and select 2 surfaces at a time and run fillet. That creates the fillet using a different technique than the edge-based filleter, and it can can build some kinds of fillet pieces that the edge-based one has difficulty with.

For example here I broke your model into individual surfaces with Edit > Separate, and then selected these 2 surfaces:



Then running Fillet will build this fillet surface:




That surface/surface fillet is kind of a more low level tool than the edge-based one, it will give you some various surfaces and you will need to do some trimming and joining of those surfaces to get back to a solid.

If you know you want to fillet something, it does help a lot if you create a more regular sort of topology for it though, you kind of want to plan in advance that your shape is not going to be poorly configured for filleting.

- Michael