Can't get pin to follow slot correctly at all

aakash_sunkari207

Hey everyone,
I've been working on a project where an inside chamber with a pin follows a slot on an outside chamber such that when you twist the inside chamber, it follows the path on the outside chamber and achieves linear motion. However, I haven't been able to get this to animate properly at all. I've tried all sorts of mates - pin slot mates, tangent mates, cylindrical mates - and I've tried surfaces and edges. I can't seem to figure this out. Could someone assist me?

https://cad.onshape.com/documents/76e13495e80ad3cb6c562716/w/0a4277775054c18484a0aeed/e/b6e0d42f1c057348de2fa339?renderMode=0&uiState=6388e0fef036a21b7214d8e2

EvanReese

Try using a rack and pinion mate. I know it sounds wrong for this, but all it does is link a linear motion in one mate with a rotation in another mate, so it would at least work for the helical part. If you want it to follow the whole path (helical and straight), then you probably need to create some dummy geometry and use a tangent mate similar to how these are done: https://forum.onshape.com/discussion/18614/mates-geneva-mechanism

MichaelPascoe

For the most control use Evans method.

The tangent mate is a little tricky, however it should work too. You have to make sure all edges are tangent if you want the "Loop tangent edges" to work. Notice how I select the face of the pin, but the edge of the slot, this gives the mate more freedom so that it doesn't break for this particular instance. Also, the assembly must not be over-constrained, the revolute mate was keeping the tangent from working and the cylindrical mate already produces a revolute constraint.

https://cad.onshape.com/documents/ef01bb24a9f7c1488a0d1fdc/w/966be8f6c9cd053c42445ee8/e/3678dc3bda71e0cba66f50d1?renderMode=0&uiState=6388ef33c0a52f0b9983a0c9



To get animation to work you can either combine Evan's method with this. Or if you only need partial control, just animate the cylindrical mate.