Lathe Motor Replacement

A while back I was fortunate enough to get my hand on a surplus 1.5KW (2 Hp) Brushless Servo Motor from Panasonic. As it turns out, the WJ200 series of VFD drives has firmware features to run a brushless motor in sensorless vector control mode. This means, that the servo can be used without using the encoder.

New Servo Motor vs Old Induction Motor - Half the Size, Twice the power :)

Fist I temporarily hooked the motor to the drive for my mill. Luckily, I found some crimp connectors that fit over the pins in the MS connector used on the motor. Using this setup, I was able to verify that the drive could indeed run the motor.

New Motor with proper connector and QD Pulley on Shaft

 Once I got the motor running, I got a matching MS connector from E-Bay and wired it with some 12-4 SOOW cable. I also ordered some pulleys and a QD bushing to get the correct ratio to be able to cover the original speed range without having to change the belt ratios inside the cabinet.

Motor Mount Concept Layout

 I have some aluminum angle on order to make a motor mount to use with the existing motor mounting plate in the lathe. I think I might be able to get the motor mounted in the cabinet by the end of next weekend, after the paint has had a chance to dry. Once that is done, I can get a better feel for the space available for the electronics. Ideally, I would like to mount the drive in the base of the lathe instead of having to have another big box like I have for the mill.

Finally, I did a comparison of the available torque for both motors. As the graph shows, the old motor had a bit of an edge at the really low speeds due to the mechanical advantage of the lowest set of pulley grooves. At the higher speeds, this advantage quickly is lost. Also, the graph shows how the new setup has the ability to run at virtually any speed between 44 and 1750 RPM instead of the old set of 8 speeds.

In conclusion, if you can find a reasonably priced high power servo motor, this setup might be useful  for other lathe restoration projects.