Absolute beginner- simulated marble shoots off in weird direction

Hi, I’m a beginner in blender, and trying rigid body sim for the first time.

The scene I’m trying to set up is a disc with some notches cut out, which spins and pushes a marble.

Managed to model the disc, a “support cube”, and a couple of empties for the constraints; one for a hinge constraint, and the other for an angular motor.

There is also a plane for the marble to roll on.

The disc spins nicely.

When I add a UV sphere in one of the notches, instead of being gently pushed tangentially by the wheel, it shoots off like a bullet in an orthogonal direction at high speed.

I have tried playing with the margin settings, but that hasn’t seemed to made any difference.

As I’m a new member, I can’t attach the file, but I have uploaded it to Google drive:


The eventual goal is to learn enough about this to use it to design and demonstrate ball machines for non-Lego GBC build events at our makerspace.

Suggestions and advice appreciated!

Thanks in advance!