Is there a method by which an angular limit to the 3 rotations in a Ball Mate can be achieved?

StephenG

The Ball Mate doesn't allow a range of min/max angles for the 3 degrees of rotational freedom.

Trying to restrict angular movement to reflect a hard interference limit in an mechanism.

mahir

I can't think of any way to do this directly with just mates. But one workaround is to use an invisible dummy part. This part can be anything that has a flat surface you can use for orienting it. In my example I used an L shape just to illustrate the mates better. Next, add these 4 mates.

1. Ball mate #1 between the "joystick" part and ground MC.
2. Ball mate #2 between the dummy part and the joystick, but not at the pivot point.
3. Parallel mate #1 between the dummy part and the ground MC from ball mate #1
4. Parallel mate #2 to orient the dummy part and constrain rotation

The rotational limits can be implemented via X/Y min/max in parallel mate #1. It will function sort of like a universal joint.

https://cad.onshape.com/documents/57acdfaae4b005c413ed9b6f/w/3fd585a46d3af1b3ba413c53/e/c8f982e2ff311457b1c60bd0

mahir

I can't think of any way to do this directly with just mates. But one workaround is to use an invisible dummy part. This part can be anything that has a flat surface you can use for orienting it. In my example I used an L shape just to illustrate the mates better. Next, add these 4 mates.

1. Ball mate #1 between the "joystick" part and ground MC.
2. Ball mate #2 between the dummy part and the joystick, but not at the pivot point.
3. Parallel mate #1 between the dummy part and the ground MC from ball mate #1
4. Parallel mate #2 to orient the dummy part and constrain rotation

The rotational limits can be implemented via X/Y min/max in parallel mate #1. It will function sort of like a universal joint.

https://cad.onshape.com/documents/57acdfaae4b005c413ed9b6f/w/3fd585a46d3af1b3ba413c53/e/c8f982e2ff311457b1c60bd0

StephenG

Thanks for the advice. I tried it and it worked.
However I only needed 1 parallel mate to achieve the desired effect.



Note: I used a surface as a the dummy part.

(Comment: Shame the Ball mate doesn't have a rudimentary way to limit the amount of rotation about the rotational 3 DOF.) 

mahir

Glad it worked out for you. Yeah, one parallel mate makes sense. For some reason I thought the Z rotation DOF needed to be removed, but it doesn't.