How to rock a part in a half pipe

Henk_de_Vlaam

I want to rock a part by tangent mates on two rounds in a ‘half pipe’. The rounds are coupled by a tangent face. When I select the rounds one by one OS sees these rounds and the adjacent faces as one face and the tangencency behaves strangely (part 2 aligns at the flat surface).

When I move the adjacent straight faces a little bit (so breaking the 'tangency' between the two rounds) then everything is OK.

Also look at https://cad.onshape.com/documents/205b989eb647be35c6cd5d6c/w/fb11df06a4c02fea2d63ef92/e/3b6f196c0bc30c138e35ebbe.

How can I make it work without moving the straight faces.

mahir

There may be a simpler solution, but here's how I got it to work.

1. Create dummy surfaces in the part studio using Offset.
2. Import the surfaces into the assembly.
3. Mate the surfaces to the original part surfaces using Fasten.
4. Apply tangent mates to the separate surfaces.

https://cad.onshape.com/documents/0b248696c976765029d8a061/w/0186679472f4185dc4ac36fb/e/83bc3bb78cb30692f4257662

mahir

There may be a simpler solution, but here's how I got it to work.

1. Create dummy surfaces in the part studio using Offset.
2. Import the surfaces into the assembly.
3. Mate the surfaces to the original part surfaces using Fasten.
4. Apply tangent mates to the separate surfaces.

https://cad.onshape.com/documents/0b248696c976765029d8a061/w/0186679472f4185dc4ac36fb/e/83bc3bb78cb30692f4257662

jon_sorrells

Since you want the part to move in a circular path, you can just use a revolute mate, and set limits on it to prevent the part from coming off the half pipe.
https://cad.onshape.com/documents/5ac6c7b9d00ebca76cb3f0f3/w/b7a78f9c6d2cfdd04daaae7d/e/80b01e855344ea5b57e252d6

Henk_de_Vlaam

@jon_sorrells and @mahir thank you for the tips. The first is the easiest, the second the most flexible one. It can be used not only on circular but also on surfaces with a different shape.

However, both these are workarounds. It should be better if OS had the possibility to select a complete ‘tangencied’ surface or only one element of it.