Re: counting encoder holes ? BEST encoder range ?

> 3. Your servo driver ~ 2 issues ~ 1. a PID multiplier will
> effectively reduce the number of pulses that the software needs to
> output. IE- if you use a 4X mult. you would only have to output

about

> 11,000 steps max from software to go the same as the max 45,000
> listed earlier (using Mach2 as and example) 2. If running a high
> count encoder & Gecko, you may have issues with error counts

because

> they are so small. In other words, depending on reduction etc, a

few

> encoder count errors may only total .00001" mechanical

error...that's

> just too small. You'll pull your hair out! The Rutex has a much
> higher error count...but if used with low count encoders, can cause
> the servo to hit an axis extent before it stops on it's own.
>
> Hope that helps...as said, I'm no expert...
>
> -Brady

your third point is interesting and pretty much where my attention is
focused.

if one has a motor that has a 2,000 step encoder, it would be similar
to a stepper with a 200 step and a 10x microstepper driver.

The encoder resides on the motor, so it is seperate from machine axes
and more on motor postioning.

A motor with 2,000 steps would move 0.18 degrees per 'step' from the
driver.

I'm not as concerned about postioning as it is for a plasma cutter
and the final accuracy is not that important.

But, the motor speed would be limited to pulse count of the software.
at 2,000 steps, it would limit the motor to 45,000 hz (for Mach2) or
22.5 rev's / second or 1,650 RPM for the motor.

Starting with a treadmill motor of 5,100 RPM at 110 V, the power
supply limit of about 66 volts (48-1.2*1.414) is 60% of motor design
or 3,068 RPM at the max voltage of the motor.

Then limiting that to 1,650 due to encoder limitations means the max
speed for the motor is roughly 32% of nameplate.

Seems that the compromises abound when trying to piece-meal parts
from surplus.

But, not have any experiance with servo's, I'm not sure just how
awful it would be.

Dave