Gunner Asch fired this volley in
:

How long is the (2) wires between your pot and your controller? You
do know you can make em longer...right?

You should read my responses to that before you ask! 'Chopper-type' PWM
controls (triac type with Zero-crossing turn-off) have very high rise-
times on turn-on. This type of switching doesn't 'play well' with 150'
long leads between controller and motor. (unless you're willing to use
LARGE-gauge stranded wire with capacitive and inductive 'tuning' at both
ends).

That sort of treatment isn't in the vocabulary or budget of most folks
seeking to run a ball mill.

Lloyd