On Dec 12, 10:13*pm, Jon Elson wrote:
toolbreaker wrote:

If cogging is real important one might try a 3 phase induction motor
and a motor controller. * We have *project that uses this aproach will
good results. *It wont be snappy but it will be smooth

Actually, typical induction motors tend to cog a fair amount if run
at very low speeds, as the induced rotor poles slip from one set
of rotor bars to the next. *There are special motors built for servo
use that have many much thinner shorting bars, and put a helical twist
to them.

Jon

Thanks , I learn somthing every day