Tony, Rocco,
Points well taken I will ad a third variation For the economy DIY'r that will show Two motors wired to HF router controllers. I think this will convert the general layouts of the said designs. Please remember these are just basic starting points for those that want to put pictures to the earlier portions of the thread.
As Rocco Said My variac will go to 140VAC which will overdrive the motor a good bit. As you can see in the first drawing we use the 240VAC Payne device to run two motors.
I Hope this helps.
Rick