Re: Timing belts

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Chris Horne" <chris@s...> wrote:

> Just wondering if a wire drive would work?
> if it did, it has got to be pretty much the cheapest and simplist.
>
> The same kind of mechanism as the old draughting table parallel motion.
> with a shaft driven by the servo/stepper, with a plain cylindrical
> pulleys at each end...
>
> The wires are captive on the driven pulley... run to the carriage..
> then to a fixed, adjustable idler at the far end and back to the drive
> pulley..
>
> I imagine it would be possible to build a machine almost as big as you
> could imagine..
>
> accuracy would be determined by the stretch of the wire under load,
> the accuracy of the pulleys and the cleanliness of the drive
> system... the pulleys could be enclosed with just a wiped, hole for
> wire exit.
>
> As I see it, the advantage over toothed belts would be that keeping a
> wire cable clean would be much easier, a simple wiper would suffice.
>
> Chris

A wire can work. take your threaded rod and put it on your gantry.
wrap the wire around the threaded rod 10 times, and then follow the
angle of the thread to determine the attach points on the ends of the
machine. (I have a CAD or pdf drawing if you like)

as the screw turns, the cable will not change angles from the ends to
the screw, that way, the geometry never changes.

the movement per rotation is based on the center of the cable diameter
around the screw.

There is a guy who has a router in his garage, vertical, and in
France, that does this and has a web site. I'm not sure of the URL
for it.

Dave