Is there any simple way to make the small turning motors turn in only one direction?

I never have tried this on a rod building motor, but have used one way bearings on stage props to do a one-way only motion. You have to mount the bearing in a fixed arbor to lock it down, You might even be able to mock it up with a hose clamp as a mount to check your action before you invest the time in a building a good frame. I know CSK makes one way bearings down to 8 MM, and I'm sure there are lots of other brands available. If you do a little googleing you'll find the component that will work best with couplings and/or shaft on your motor. Its not hard stuff to do.

Dennis,
I assume that you are referring to the timing motors that are commonly used for drying rods.
Generally speaking, there is no way to guarentee the direction of the motor on start up.
If you always want it to start the same way, you can simply put pressure on the blank in the direction you want the rod to turn, as you turn on the motor. If you use hand pressure on the blank in the desired rotation, the motor will start correctly every time.

Roger

Thanks very much for the info guys!