Tangent Mate - edge and plane - when I animate the motion, the whole model displaces

rob_mackie008

I have a silly model. A "live mouse trap" as an exercise to see what I can do in onShape. In this model I have a shape that rotates on an axle, and another shape that rotates on another axle. When the second shape moves, it leaves space for the first shape to fall. To simulate this, I mated an edge of the first piece to a top plane of the 2nd piece with the tangent mate. I figure when the 2nd piece moves out of the way, it will "drag", by its tangent mate, the first piece into a new position - the position to which it would have fallen in the real world. (in fact due to geometry, it only moves part way, but I don't mind that.)

Mostly, it works as expected, given the geometry I have. HOWEVER, the line where the surface and the edge are tangent (a line which moves across the surface), remains fixed in the geometry with respect to the coordinate system defined by the "center". So as my parts move, nicely coordinated with one another, the entire assembly has to move across the screen in a manner that is totally NOT intuitive, nor desired. 

Wondering what I have done to lock that position to the coordinate system.  Here is my model (I think you can use this link?)

  https://cad.onshape.com/documents/b536b8ecc26376a7634c780f/w/c5c86be766f24280b388d13c/e/577fb3a95ec1ad3db6329980 
  
To see the issue, select "trap arm motion" revolute mate, right click and animate it.  
The intended effect is that the balance tube and the pendulum move as they do, with relation to one another, and that the over all assembly, the "chassis" stays in one place..

Any explanation of what I've done wrong and how to think about it - well that would be very welcome.

Thank you, 
Rob.

romeograham

Your problem is simple: you need to fix the Chassis in space so that it doesn't move around when the other parts are animating.
I used a Fastened mate between the bottom face of the Chassis and the Origin.
You could also just Fix (Right-click on the Chassis component and select Fix), but a Mate will generally be more robust. 

romeograham

Your problem is simple: you need to fix the Chassis in space so that it doesn't move around when the other parts are animating.
I used a Fastened mate between the bottom face of the Chassis and the Origin.
You could also just Fix (Right-click on the Chassis component and select Fix), but a Mate will generally be more robust. 

rob_mackie008

Wow that is simple, and easy to do. Thank you!