Configurations and in-context updates

CSchmidt

Can someone help me better understand how in-context changes work with configurations?  The link below contains a "near" and "far" assembly configuration that I want to drive the solution for the "part 2" configurations of "near" and "far".  I'm very new to onshape but this is a test of the capability of the onshape software.

https://cad.onshape.com/documents/62d3b5bb28ca4c453e9dcf45/w/b49a3342b1cf1ac494a18e20/e/805abc891f408ae64289f425?configuration=default&renderMode=0&uiState=63014bb88ecc1b6bcec511af

eric_pesty

One option would be to use a separate branch where you update the context to use the far configuration of the assembly but that gets a bit messy. What you need to do here is create a separate context for the far configuration.

The difference with other CAD is that contexts are "independent" from each other so the near and far contexts aren't actually related so while you can update the one context between near and far, you can't quite directly pick which one to use in each part configuration.

The way to deal with this is to create a "new context" for the "far" configuration, and configure the part to reference that context in the "far" configuration. In this case I edited sketch 1 to include regions that go up to to the "far" context and configured the selection of extrude1 but there are may ways to do this. For example a "move face" on the end of the part "up to" the far context also works (try unsuppressing "move face1" in the near configuration). Or you could have create a reference plane for the end of the part is configured to be coincident with either the near or far context, etc...

Note that there is no need to "convert" the edges of the context as you can directly reference them.

Hope that helps:
https://cad.onshape.com/documents/373fa56230e061663261fba1/w/f403936d800937feb3036beb/e/b2811c8a707f1660bdf4c74b

CSchmidt

Was hoping to do all this in the sketch 1 (without creating extra features).  This appears to be a limitation with the software.  Seems like a lot of work to accomplish something very simple.

eric_pesty

In the example above it is all in sketch1 and there are no extra features required...
Adding configurations to the part and a second context does seem like a bit of extra work in a really simple example like this but the tradeoff is that it is "stable" and won't just rebuild in unexpected way, which gets more important as the complexity of your model increases...

The only real "limitation" I see if if you want to have something that constantly updates automatically as you move things in the assembly. Solidworks was in theory able to do this but it would sometimes often stop working for no apparent reason so that "in context" relations had to be used very sparingly.

So I wouldn't necessarily call it a "limitation" but more of a tradeoff: a bit more effort in exchange of stability/predictability, and also a lot more flexibility as this allows creating contexts in multiple assemblies.

In this use case, (controlling an arbitrary length of a part), I would likely use a configuration variable instead as this is a simple and robust way of doing something like this:
https://cad.onshape.com/documents/373fa56230e061663261fba1/w/f403936d800937feb3036beb/e/fa66080f3cf860e4c383a8bb