Unable to create movable linkage

joseph_newcomer

I have a model where I am connecting an arm from a servo to a linear slider.  I am using a representation of a solid wire that is used to make the connection.  I have a problem.

With nothing connected, the slider moves and the servo arm moves.

If I create a revolute mate between the wire and one of the moving components, everything works fine.  I can rotate the wire, and if I drag the wire, the connected part will move.  But if I connect both ends of the wire, the resulting model is unmovable.  I have tried connecting the wire to the slider, and it works fine; I have tried connecting the wire to the servo arm, and the wire can rotate and the servo arm can rotate.  But when I connect both ends, it becomes rigid.   What have I missed?

The share link to my (public) model is 

https://cad.onshape.com/documents/9c65dae5ba9f40e5873510e7/w/e616647a24c89275f9f2733d/e/6fb1fce46ba27f32b90fb3a0?renderMode=1&uiState=61d2cda03a7c3d6a862f13e3

and the component is Assembly1.  This is a device which mounts on an XY table and will push objects around on the table.

steve_shubin

@joseph_newcomer

https://cad.onshape.com/documents/c04c9089468dca011c34d273/w/2f8c93afb770875e6d84e378/e/b5b4cddf0cb2fb94afc9f3ab

That gold piece is colliding with the main part. So you may want to elongate that gray piece that slides up and down

steve_shubin

@joseph_newcomer

I was not able to copy and work with your document

I had to export the assembly and then import it and apply my own mates

But here’s what I believe is happening with your document

You have one part — a bent wire

You have a revolute mate at each end of this bent wire

In this case the two revolute mates are fighting against one another as one mate is trying to pull the other mate off of its point of connection

In your case, you need to use a revolute mate at one end, and a cylindrical mate at other end

On your assembly, I used a cylindrical mate at the connection of the wire to the servo arm

steve_shubin

@joseph_newcomer

https://cad.onshape.com/documents/9c256192ed4d0b9c70753ac4/w/7266693fb4ff852b232988da/e/4aaca3fb1d00014d61471849

I looked at the assembly some more

It’s a matter of where the hole is for that linear slider also. Especially when using a slider mate

I moved the whole a bit closer to the main body. But I still ended up having to change from a slider mate to a planar mate. As a result, I was able to use two revolute mates — one at the servo arm and one at the top of the linear part

If I would’ve had access to your sketches I might’ve been able to get by with using a slider mate also

I know it’ll work because I made up another document showing that you can use two revolute mates in combination with a slider mate

https://cad.onshape.com/documents/ba35b884074f1aa303e51672/w/cbbf258d8d66e4cb5ced78ec/e/c949d025836dbdf461c8747e

steve_shubin

@joseph_newcomer

https://cad.onshape.com/documents/e736543fb1a0d5fa84202f8a/w/41bf654cc947bf12a74ea2c1/e/ff147497932da1005f2ee457

Here is an assembly where the revolute mates are NOT on the same plane and the linear part uses a slider mate. And yet it works.

But all the parts were made in the same part studio — in position — relative to one another

But in your case, it’s easiest to use a more forgiving mate combo. That being cylindrical / revolute / planar

steve_shubin

@joseph_newcomer

Another way of dealing with this is by using In-context editing

This will allow you to have two revolute mates that are not on the same plane, and to have a slider mate