Hi andaras, it looks like there are some accuracy problems with the fillet-like surface there.

Even though it is joined to the other one, the actual surface itself does not pass very closely to the other ones.

That's the reason why the projection does not join up, the projection is calculated on the surface and when the surfaces are not close to one another, the projections will also not be close to one another.

How was that in-between piece created? When I untrim it, it does not appear to be a fillet, it's a rather strange wavy thing:





Also various pieces of the model are problematic, when I look at the underlying surface for this part here:



You can see there are some chaotic control points in some areas of it:




There is just a low level of accuracy throughout the piece, for example this spot here:





That's a gap of 0.01 units, which is rather large.

Were those pieces created inside of MoI, or did they come in as an import from somewhere else? Or was the object possibly modeled at a different scale level and then scaled to its present size?


So what I would do would be to run ShrinkTrimmedSrf on those larger pieces to throw out the bad parts of the underlying surface, then untrim them (select an edge, use Ctrl+A to select all edges, then delete), which gets you this:



Then select those 2 faces and run Fillet to generate an actual fillet surface between them. The fillet surface will be touching each of those surfaces to a much higher level of accuracy than the previous ones that just looked like fillets were:




Now with the accuracy of the surfaces improved, you can also project on to it and have the projected pieces match up well. I've attached a 3DM model file (project_join_problem2.3dm) that is ready to have an accurate projection done.

- Michael