300 IPM - machine resolution and encoder slots

I think a 400 slot encoder with a 5 TPI screw should give you:

400 X 4 (quadrature) X 5 (rev/in) = 8000 counts/in

This is equal to a res. of 1/8000 = .000125 counts/in

Am I missing something?

Also, as far as steprate requirements, for 300 in/min (5 in/sec) at this
resolution you'd need:

5 in/sec X 8000 counts/in = 40,000 steps/sec

I know of several PC controllers that can do this easily, even up to about
100,000 steps/sec. That would allow 1000 slot encoders (w/ quadrature) and
5 TPI screws to run at 300 in/min with a resolution of .00005"/count (20,000
counts/in). Can somebody double-check this for me?

Carlos Guillermo
VERVE Engineering & Design

> > Ok Guys!
> with a 400 slots encoder and my 5tpi screws and no reduction on the
> transmission it would give me 0.0005" ressolution right?
> Is there a way to multiply the encoders couts?let's say x4,that
> would give me a much better resolution.
> I don't like the idea of using a belt reduction,to increase
> resolution,since it might intruduce backlash.(I've zerobacklash
> screws).