Hi, BurrMan.

The main thing I was trying to understand was how to use MoI to construct the section between the cylinder and the retangular block.

In ViaCAD Pro v7 I can use the Lofted Solid tool to make the transition, I couldn't see an equivalent in MoI, so I experimented with the construction.

Working in MoI, my method was to extrude four rectangular surfaces and four semi-circular surfaces (for the cylinder), which I then joined piece by piece with the Blend tool and using a Bulge of about 1.3 to get the right shape. I then capped the ends and used the Join tool to make it into a solid.

My attempts to fillet the curvy edges were a bit hit & miss - I knew this would stress MoI's filleter due to the fade-out of the edges, but the slightly odd thing was that some fillets were made underneath the geometry whilst retaining the areas that should have been deleted.

At this point I think I exported to ViaCAD as a .sat file and it came in looking Ok.

I tried to use ViaCAD to fillet and shell the part, which initially failed. The Check Object tool reported the solid as being damaged (edge gaps, I think) and also offered the option to repair it. After which this part filleted and shelled OK.

I made .sat and .step exports, with the intention of bringing them into MoI for further working and it was at this point that I found the problems with some wonky geometry.

I'm pretty sure there are other ways to make the part in MoI, but I'm still learning!

Martin.