Working on an intake CAD, and I’m at the stage of starting to mate together the parts in the assembly. After mating shafts to the respective holes on the intake plate on one side, I’m getting overconstraint errors when I try to mate the shafts to the holes on the intake plate on the other side. When I click on certain things that should be parallel, I also get a measurement of the slightest angle in some positions. I am using cylindrical mates in some places rather than all revolute, as I’ve seen recommended. But still the overconstraining mate error, and I think it must have something to do with things not being parallel that should be parallel… not sure how they got into that state. I assume others may encounter this - is there a preferred method to troubleshoot and correct? Thank-you.
I’m assuming you are coming from an understanding of SW mates. Onshape mates work quite differently.
Unlike SW, Onshape has unique mates that eliminate all unnecessary degrees of freedom. You need to select the correct mate. You should only have and need as many mates as you have parts, and more often than not you should have less because you should be grouping all items that never or rarely move relative to each other.
My guess is you are adding more than 1 mate to a single part. You need to instead select the correct mate you want for the application and use just that one.
More helpful would be sharing your document so we can see exactly what is happening.
Some pictures could help in figuring this out, but I’ll try and help best I can. Is the over constraint error you are getting related to how the two sides of the intake plates are mated? Are you trying to use the shafts to locate the plates? Any time I’m placing shafts they almost always only have a single fastened or revolute mate.
My advice would be to start by fastening the two intake side plates to each other utilizing an offset, then mating your shafts to only one plate.
That solved it, and then I also fastened the arms on each side to each other with offset, and now the overall assembly is moving as it should. One side of the intake is not connected to its mount at all, but it works because the thing is symmetrical anyway. I would not have thought I needed to do it this way, but glad to learn. Thanks a lot!
You’re welcome. I always try to approach assemblies as looking for the solution with the least mates, and trying to think about how the parts may change. I try to pay attention to where I can mate things so they are less likely to break when a part design is modified, but that’s mostly learned from having messed up mates a lot.
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