Tangent Mate Feature

tyeth_gundry

Hi readers, I'm a software profressional, with a fair bit of cad experience, but an onshape novice. Working through the learn guide while modelling a modular Pinch Valve based on a sliding carriage depressing a sprung lever.

https://cad.onshape.com/documents/86d6c2bfbb3298e493516ad9/w/1e0df0355910e4599ea9cd9b/e/ef19a4630b3a7828d985f69b

I've just started my Assemblies training, and am trying to mate a ball to a ball (lever top to chock bottom), as a tangent mate, but it fails, I believe due to using a swept curve instead of some normal thing. If I mate the tops of the balls then the carriage / chock becomes locked. It wont let me select both surfaces/faces, so do I have to create some alternative curve/surface type to get around some onshape shortcoming, or maybe a rack and pinion type thing, or am I using it wrong?

https://learn.onshape.com/learn/course/fundamentals-onshape-assemblies/mating-assembly-components/onshape-mate-types?page=4

GregBrown

Have you tried the Ball mate type? Also it is possible stack part instances and mates (ball to one part instance, slider from that part instance to the next… in whatever combination you might need. 

Just be aware that this is not a mechanism dynamics environment so you cannot directly model collisions/contact, unless you use some tricks like the one mentioned. 

tyeth_gundry

Ah I did wonder if the collision thing existed, or whether (judging by other posts and your comments it is the case) you must create hidden surfaces/paths etc. I realise I can fake the animation, but I'm more interested in testing a concept before 3d printing so the assembly/animation was just good practise. I did try ball, but the lever position remained fixed and the block rotated like a ball joint and then adding the slider failed. I think the slider as a secondary makes sense. I tried a slider first on the fixed rail and moving chock/block/carriage, then the rotation on the lever, but using the faces of the balls fails and using the points (vertex?) instead of face/surfaces fixes the objects.