Re: 20 Amp 80 V $99 DC Servodrive

--- In CAD_CAM_EDM_DRO@egroups.com, "Ian Wright" <Ian@i...> wrote:

> ----- Original Message -----
> From: Ron Ginger <ginger@s...>
> OK, I think I see the problem.
> If I had a 1000 line encoder on the motor, and a 3:1 pulley ratio

to the

> screw, I would need 3000 steps per rotation, or 30,000 steps per

inch

> given 10tpi screw. So my software would have to generate 30,000
> steps/in, vs the 2,000 steps per rev for a 200 step stepper motor

direct

> coupled to the shaft. This might be byond the speed a PC running

windows

> could do. Your pulse multiplier of X10 would take each incoming

pulse

> and generate 10 pulses, so the software would only have to do 3,000
> steps per inch.
>
> Or presumably you could move the encoder to the leadscrew when the

pulley

> ratio would not come into play. Don't servo motors use quadrature

to get

> 4000 steps from a 1000 line disk?
>
> Ian
>
> --
> Ian W. Wright
> Sheffield UK

You are correct about the 4000 counts; a 3:1 ratio would bring it up
to 12,000 per rev.

The encoder must be on the motor shaft for loop stability. If it were
on the pulley, the belt "give" or compliance would certainly exceed
0.05 degrees (+/- 1/2 count for a 1000 line encoder) and the loop
would be impossible to compensate.

Mariss