Well I modeled the part up to a point: The fillets are show stoppers. As I was fearing, here the OCC kernel fails miserably.
So I was mistaken when I said
normandc wrote:Well the part can certainly be modeled in FreeCAD
At least, not following the sequence shown in the video. And we may have no choice but to change certain conditions, like avoid edge tangency at a few places (among them the rounded end of the tombstone).
For example, try to apply the 3.99mm fillets to the rib, and admire the result! That big a radius means it intersects the base and it creates "ridges".
To get the fillets like we want, I don't see any other choice but to model the rib as a separate part, apply the fillets, then fuse the result to the main part. Unfortunately that means we cannot link external geometry.
The 2mm fillets on top of the cylinder and at the bottom of the bosses "explode" the part (some faces disappear) or simply fails to compute with a "Failed to create fillet" error. I can only get a 1mm radius for the bosses.
Even if making minute changes so edges are not coincident allow the fillet to succeed, FreeCAD (or maybe OCC) doesn't allow us to control the condition of fillets when they intersect other edges.
Here I changed the height of the tombstone profile so its rounded end comes 0.1mm short to touching the top face of the cylinder. I thought that would solve the problem.
Applying a 2mm fillet now works, but look at how it adds a "bump" over the tombstone:
Not at all what we expect. In commercial software, you can control how the fillet will react in similar conditions.
So it's a little disappointing...