Tapping Set with chucks for or Mill Drill Press

[jjr2001]

Strange re: " The previous motor was a brushless variable speed DC motor.
The lathe is now much improved due to the increase in torque especially at low speed."

One of the most common criticism of VFD was that they lost torque at low speed.
My Brushless DC motors have lots of torque at low speed.

Ralph

Well I guess it all depends on the frequency you are feeding the motor.
The old motor was a 750 watt brushless DC for the MicroMark 7x16 mini lathe. I replaced that
with a 1HP 3 phase inverter duty motor and VFD..Why?
Well the original motor replacement cost $335.00. For that cash I was able to pickup
on Amazon a 120v VFD with 240V 3P output rated at 1HP and a matching motor and it was less cash for the pair
than just the cost of the replacement motor alone! Crazy isn't it?

New VFD plus 1 HP Motor for Mini Lathe or any lathe

Ok the new motor is much larger, I had to mount the VFD and Motor external to the lathe but
I have a much superior lathe system compared to the way it operated before. How much of
that "new power/torque feel" is due to the mass of the new motor and how much is related to
the reduction in speed I now have since the new motor is lower in rpm and I also added a jack
shaft and reduction pulley set. I never used the old motor past 50 or 60 percent of speed.
This one I will on occasion push it up to 75 percent of speed. (more than enough for carbide
and nice blue chips)!

Now the effect that I see is that this new setup does not choke at low speed when cutting off or
taking a large cut in steel like the old original little motor did. I keep the load on the lathe down to
about 1HP by setting a current limit on the VFD and would never think of going back to that
brushless original equipment motor even if it were free!

Here is a little torque/rpm chart with an explanation for KKurtz engineering:


Cheers, JR