Mating THREE parts

eric_schreiber

I Fastened Mate pulley on a hub with Fastened Mate screws.
But when I mate the Pully+Hub assembly to the Servo Motor the Fastened Mates shift.

Any thoughts?

https://cad.onshape.com/documents/1ac006629d1f18ddfa25dbaa/w/5ff21e9e433b2bd13dbfc637/e/c6dc10ad3fb7af9e7a024fd9

mahir

I took a closer look. Actually, you should be able to add a fasten mate between the pulley and screws. Just make sure to pick the round side of the slot that aligns with the holes in the hub. However, if you wanted to mate between the screws and hub that would also be possible. You would just need to add a Z offset in the mate definition that is equal to the hub thickness.

Btw in general fully modeling male/female threads is considered unnecessary and computationally expensive. If you have control of the models I would surpress them. It also makes mating easier since you have a nice clean hole or cylindrical surface to pick for mate connectors.

mahir

Looks like the hub is mated to the pulley using a revolute mate. The screws aren't moving. It's the hub moving relative to the pulley while the screws remain fastened in place relative to the pulley. Just switch out the revolute mate for a fastened mate. Also, the screws should probably be mated to the hub not the pulley, since there aren't really any features on the pulley to locate the screws.

eric_schreiber

@mahir Thank you for your time and attention. 
The Hub+Pulley+Screws need to be all fixed. When I change the revolute mate for a fastened mate, the Hub shifts 45 degrees.
Can you try it on your end?
Also, how could I Fastened mate the screws to the hub with the pulley in between?

mahir

I took a closer look. Actually, you should be able to add a fasten mate between the pulley and screws. Just make sure to pick the round side of the slot that aligns with the holes in the hub. However, if you wanted to mate between the screws and hub that would also be possible. You would just need to add a Z offset in the mate definition that is equal to the hub thickness.

Btw in general fully modeling male/female threads is considered unnecessary and computationally expensive. If you have control of the models I would surpress them. It also makes mating easier since you have a nice clean hole or cylindrical surface to pick for mate connectors.

eric_schreiber

@mahir
I tried now to fasten mate the assembly from the other side of the hub and it works better.
Indeed, picking a better 'anchor' edge or point worked better. I was anchoring the mate point wrong.
Thank you for the good tip on supressing threads.