Issue defining motion link between two cylindrical joints.

[alexanderhosford]

I have two cylindrical links that I would like to move in unison. They are representations of stepper motors for the Z-Axis of a small CNC device.

Each motor component has a cylindrical join defined, that determines the rotation of the shaft. 

The first video shows what is happening when the motion link is defined as part of a larger assembly.

As the assembly contains lots of components and joints, I was at first sure that I had done something wrong. I therefore created a second much simpler design, containing only two instances of the stepper motor.

The second video shows the same behaviour in the simplified circumstances, and how I am defining the motion link.

The behaviour occurs regardless of the order in which i define the joints or the values which I enter.

The joints behave as expected on their own, as do all other joints in the design.

There is a grounded component in the large assembly file, but not in the simplified test design that contains only two motors.

Although i have previously defined many motion links, this may well be the first time I have attempted to link two cylindrical joints to move in unison like this.

Is this a possible bug? Or am I doing something that does not make sense?

Thanks in advance for any assistance

[jhackney1972]

You will need to share your model to get an accurate answer.

[alexanderhosford]

Please find attached the simplified model in which the behaviour is occurring.

In any case, were you able to view the videos and see the issue I am describing?

[jhackney1972 · Accepted solution]

The issue you are experiencing is coming from the initial Revolve Joint on the motor.  You have it between the shaft and a body that is not either grounded or joined in the assembly.  I redefined this joint between the shaft and the mounting plate of the motor, a body I can easily ground or add a rigid joint to in the assembly.  Using the new revolve joints, the issue is solved.  Take a look at the Screencast.

[alexanderhosford]

Thanks John, 

I had also gone down the route of redefining the joints on the motor component before I saw your reply, having made a test component up with just a gear and a shaft and subsequently being able to link just like I wanted.

I believe the rotation was defined around the rotor and the stator of the motor I had modelled, albeit some time ago so I'm not 100% certain.

In any case I have redefined all the joints now to be more sensible and in sequence - I am more methodical about this these days but the motor component is a few months old now and I fear may contain many of my older bad habits.

Thanks again for the assistance.