I think you will end up needing a new VFD, too!

For testing, I borrowed a 1HP Teco VFD from my surface grinder.
I decided to buy a 2HP Teco VFD dedicated to this machine so
that I can use a bigger motor if I need it. For now, I suspect
the existing motor will work ok. I still think that an 1200
RPM motor would give me a big increase in low speed torque
and if I find a cheap one I will try it out.

What does it do when it fails to start?

It hums. I started using a custom VF curve and started the motor
out with a higher percentage and I made it start reliabily.
I think the default it 5% and I pushed it to 20% to make it start
well. However I think this means I should not operate the motor
at too low a freq or it will burn out the motor.


If the VFD can be set for higher than nominal amps, try setting it as
high as it will go.

The VF curve change solved the problem. I also enabled a torque boost
but that didn't seem to make much difference. The VFD will also tolerate
an overload for 1 minute.

thanks for the advice!
chuck