In Context Boolean, Mate Connectors Gone

famadorian

I edited a part in context, then added a derived part, transformed it and did a boolean union on the parts, but when I return to the Assembly, the mate connectors of the last derived part are gone?;)

famadorian

Hmm, I created a new part studio and a derived part studio and inserted it into an Assembly and the same thing happens. 

Here's the file: 

https://cad.onshape.com/documents/2d7dbc7b1261d40143e5ca98/w/fa81af3c990d6fb181f1d4c0/e/51a6f59a7d97cc92bfeee40b

Something I'm doing wrong here?;)

famadorian

As you see above, the left part is missing the mate connector in the Assembly, even though it exists in the Part Studio

famadorian

This got me stumped. What am I doing wrong here?;)

famadorian

I'm beginning to think this is a bug?

Happens almost all the time

famadorian

Should I file this as a bug?;)

alnis

My understanding here is that the mate connector that's not appearing in the assembly is owned by the second part (that part being "deleted" through the boolean that combines the parts), so when you insert the blue/first part, the mate connector associated with the (destroyed) grey/second part doesn't come in. I put together this example document that might help:
https://cad.onshape.com/documents/727e77bcc01633e6a48e5c08/v/703f703100ef01235b24781a/e/d8f7436596d5fb2a662499e8



Note that if we reverse the order in which the cube and disc are selected, we keep the mate connector when we insert it into the assembly, and the second gray part becomes missing since it was consumed and added to the cube with the mate connector.


This behavior definitely is a bit tricky. I wonder what would be a better way to handle it. One option would be to transfer ownership of mate connectors to the new "parent" part when a part with a mate connector is combined with another part, but I haven't thought much about this and there is probably some sort of drawback that I haven't thought of.

In short, I think this is expected behavior, but it's not super intuitive since the boolean feature merges geometry, but doesn't seem to add other data from the parts that were booleaned together.