Re: [CAD_CAM_EDM_DRO] Re: Timing belts

Hi Chris,

As an old school draughtsman trained in the early 70's I can give you my
experience of using this type of drawing board for the odd hour or two.

If you move the square from one end quickly the motion goes out regardless
of how much tension is one the wires. This was avoided by gripping the
square at the centre. There for if you had more back preessure on one end of
your gantry the wires will slip and cause the motion to go kak.

Regards,

Terry

| 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
|
| ..--- In CAD_CAM_EDM_DRO@yahoogroups.com, "mmeyers1111"
| <mmeyers1111@y...> wrote:
| > I'm building a 3ft by 4ft router. Has anybody successfully used
| > timing belts to control gantry movement and could you recommend a
| belt
| > type and a supplier? Should I expect backlash problems controlling
| > movement over a 4 ft distance? Other problems?
| >
| > The belts and pulleys seem to be relatively inexpensive, it seems
| > relatively simple to implement, and gantry speed could be changed
| > easily with pulley diameter changes. How come timing belts don't
| seem
| > to be used more for cnc router control?
| >
| > Mike