Learning indexing servos by reverse engineering a system

[JeffKiper]

I have a customer that wants to convert about 7 to 10 1398 Servos to 2098. They have both PDM and DDM versions. They would like to standardize on 1 family of drives.

So here is my question is if I have a 12.466” Circumference roll with an 8:1 gear ratio from the motor and 2000 PPR encoder on the motor does that give me a 0.00077” per pulse of the encoder? I think so, but I don’t know motion systems
Thanks for your help

 

[Steve Bailey]

Your arithmetic is accurate, although that nominal 2000 PPR could actually be 8000 counts per revolution if it's a quadrature encoder.