How to Mate these Parts?

brucebartlett

@philip_thomas @billy2 the only issues is, it takes 3 mates (same as old CAD) and is not a logical solution for the general punter. I haven't used SW for a while but seem to remember symmetric mate for situations like this, maybe we need a symmetric mate which could be added from 3 mate connectors. 

philip_thomas

We def need something - I will talk to the assembly group tomorrow

Don_Van_Zile

philip_thomas said:

We def need something - I will talk to the assembly group tomorrow

@philip_thomas - Can I change this to my accepted answer!?

malay_kumar

I will throw some light on why we don't allow between mate connector using two part instances. Currently mate connector is always defined with respect to one rigid part and it's location is calculated before all mates are solved. If we allow mate connector to use geometry from multiple parts then it's location will be dependent on two parts relative position and so it has to be part of mate system solve. With some work and new concepts we can potentially support a (new kind of) mate connector which is computed as part of solve. It could potentially add some confusion also in understanding if location is before solve or after solve (but probably not a real issue if behavior is robust).

We understand that in practice most of the time two parts involved are rigidly connected so we may allow it in future if we can detect that though it will fail if that condition change. We could also support these kind of use cases modeled as some kind of mate between three parts like width mate. We plan to support it in future some way but not necessarily as a mate connector definition. Currently it can be defined using in-context and defining in partstudio. 

brucebartlett

Hi @malay_kumar thanks for joining in and shedding some light on how the mate connectors work. Calculating before the mates are solved makes sense and sounds like going across multiple parts could create solving issues. 

Rather than a mate connector solution for this, I would be happy to see symmetric mate, which would be a new mate category as it needs 3 mate connectors rather than 2 but would solve this issue and could be used in multiple other applications as well. 

Here's my back of an envelope icon sketch

Don_Van_Zile

@brucebartlett I think something like this would be what would be needed "internally" if/when Onshape decides to implement a Dynamic Part Mirroring command. However, it would still be a much welcome addition for obvious use cases as we've shown.

billy2

@philip_thomas just finished video, been on vacation.

Fantastic video. You hit it out of the park, home run!

Can't wait for the next one.

Link to Philip's assy video