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Tangent Mate is bistable (and I don't need it to be)
nathan_jenkins610
Member Posts: 6 ✭
I'm using tangent mate because the two objects make contact at curved points on both parts. The first image is how I'd like it to be mated, but if I click and drag it to the left or right, it will pop over to the other constrained position. I understand WHY it's bistable, I just dont want it to be. Is there another mate I can add that will disallow the unintended position without overconstraining the assembly? My assembly is parametric so I can't just fix it in the right place.
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Answers
I understand to some degree why tangent mates are bistable too, but the more users flag these examples as bugs with support tickets, the more that Onshape will be likely to focus some effort on fixing the issue. It's really hard to use a Tangent mate with any reliability due to their unpredictable tendency to flip like this.
Simon Gatrall | Product Development Specialist | Open For Work
Agreed with @S1mon , tangent mates like to flip even when they "shouldn't"… To solve your issue though, I would add an explicit mate connector in the part that is aligned with the tangent of the top edge (you probably already have some stable reference sketch or something that you could use for it). It will also perform better than using tangents!
I also fully agree. A tangent mate in a 3D model (maybe other than in a sketch) could refer to surface normals in order to make a tangent mate stable by default. That is what I would expect.
@S1mon do you recommend I make a bug report on this or are you just commiserating? Thanks for the reply.
@eric_pesty I could do that, except the parts dont actually meet at the point where a horizontal plane would be tangent. as you can see, its the inside of a curved part even on the top. this means the exact point where it is tangent is dependent on the specific geometry of both parts, and my part is parametric so I can't just calculate it backwards.
Right, you would need the geometry in the part studio(s) to locate the MC at the correct height. Not sure how your document is setup but it looks like it would be beneficial to have both parts modeled in the same part studio!