I'm having a problem with the fillet feature.

I have a part which is a node of a truss. It has 6 cyllinders in the basal plane and then 3 cyllinders spaces 120 degrees apart inclined away from the basal plane by ~54 degrees. This part was created by mating the cyllinders in an assembly, then saving the assembly as a part and using "Combine->Add" on all cyllinders.

I want to fillet the node, so that I have a certain fillet radius between all the strut joints. My struts are 25 mm long, between 3 and 5 mm in diameter. A constant radius fillet of radius 1 mm works perfectly. When I attempt to increase the fillet radius to 2 mm, I get many errors.

Some joints work.

Some joints give the error: Cannot create a valid fillet/chamfer because either this filleted/chamfered face is self-intersecting or its loop is bad.

Some joints give the error: The radius of the fillet is too large to fit the surrounding geometry. It may be too large because it cannot fit within a tightly curving face near a selected edge or it would inappropriately eliminate an adjacent face. Try adjusting the input geometry and radius values or try using the "Face fillet" option.

Why am I getting these errors? I could understand if the radius I was attmpting was obviously too large e.g. it extended beyond the end of a strut or something. But SOME joints are working with the 2 mm fillet radius - just not all of them.

Ideas??

Thanks,

Adam