Re: [CAD_CAM_EDM_DRO] Timing Belts vs. Rack and Pinion drive

Terry;
you can fix the screw stationary and make the nut spinning
mariano


Terry Toddy wrote:

> How do you support the leadscrew on a large machine? A 3/4" dia. x 10'
> long leadscrew will have considerable sag when the gantry is at one end
> of the machine.
>
> As for the timing belt drive I think that as long as the length between
> pitches is consistent any cumulative errors or stretch can be
> compensated for with software. When driving the gantry from both sides
> the trick is to get the belt tension equal on both sides.
>
> I only need .060" accuracy over 10', but it is a challenge to try to do
> better.
>
> Terry
>
> JanRwl@... wrote:
> >
> > In a message dated 23-Oct-00 10:38:47 Central Daylight Time,
> > tltoddy@... writes:
> >
> > << this is my first cnc project. >>
> >
> > Hope it isn't your last! I have no clue what kind of accuracy, backlash, and
> > repeatability you need, expect to get, will experience with the proposed
> > lashup, but for the "X-Y Tables" I have built, with working-areas from
> > 11"x17" to 5'x12', I used precision-rolled lead-screws; SS ACME on the
> > smaller ones, with Turcite preloaded nuts, and 1/2" pitch preloaded
> > ball-screws on the huge one. (Too expensive!). Timing chain, even Berg
> > stuff such as their Min-e-Pitch, is accurate enough, unless you will be only
> > cutting weldment parts.
> >
> >
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