Re: [CAD_CAM_EDM_DRO] Re: Synchronizing Two Servo Motors

Yahoo wrote:

> Jon,
> Thanks, to you and a couple of other guys, for the ideas on big machines,
> but this is a small one, only 24" travel X & Y. I've thought of many
> different mechanical solutions, but every one ends up being too complicated.
> The only practical one would be to slave the two screws by a chain or belt,
>

If you belt the two screws together, you don't need two motors!

> but it seems like this could cause the motors to fight, leading to potential
> oscillation problems or excess current when idle. Setting the controller to
> stop everything when any channel faults, and slaving two channels for the
> dual lead probably would work, except in case one of the motor couplers
> failed. This failure also would not be covered by any electrical solution
> that relies on the motor encoder signals, as they are mounted on the motor,
> not the lead screw. The only really fail safe solution would be a
> differential switch controlled by a timing belt at the far end of the
> screws. If only I could find a belt long enough. It would need to be roughly
> 6' and anything too thick would eat up a lot of torque just in friction.
>

Hmm, yes, 6' of belt or chain would flap a lot. If you constrained it
with guides, that would add friction.

Jon