Re: Treadmill motors as Servos

Hi Les,

Your consideration and experience is Greatly simplifying what
could be an expensive and frustrating, trial & error experience
for me.

I am as grateful as a person can be.

I'll go with the surpluscenter encoders...they're proven to work
on your setup. Plus I'll have a few spare motors for (something)?

I'm looking at these pulleys

http://www.sdp-si.com/estore/CoverPg/Shaftloc/HTD5_Pulley.htm

I'd get a 20 and an 80 for 4:1 reduction.
I think I've got that right.

John


--- In CAD_CAM_EDM_DRO@yahoogroups.com, Leslie Newell <lesnewell@...>
wrote:

>
> Hi John,
>
> > http://www.usdigital.com/products/rotary-kit-encoders.shtml
> >
> > Is there any advantage to using these over the others?
> >
>
> If they do one that fits the shaft on your motors it will save a bit of
> hassle. Otherwise it doesn't make a lot of difference. Depending on
> gearing you probably want somewhere between 200 - 400 CPR. Increasing
> the CPR increases the positioning accuracy but reduces your maximum
> speed. Ideally you want to be using close to the maximum available

pulse

> rate when moving at rapid speed. Remember you effectively get 4 steps
> per encoder line so a 200 CPR encoder is 800 steps/rev.
>
> > What about the gearing reduction, How did you do it?
> > Timing belts?
> >
>
> 5mm pitch, 15mm wide HTD timing belts. I used them because the spacing
> between the pulleys worked out right with the reduction ratio I wanted.
> Theoretically HTD have slightly more backlash than trapezoidal
> 'classical' timing belts but it is so small that it makes no real
> difference.
>
> > I don't want to push my luck with the questions, though, I'm trying
> > to do it in the open for anyone else who may be follwing along.
> >
>
> No problem. :-)
>
> Les
>