Lathe Motor Upgrade (5 Jan 2006) My  lathe  came with a 400 watt, single-phase, single-speed  motor.  Changing spindle speed was accomplished by changing the belt-pulley position.   These changeovers were  not particularly difficult, but certainly  not as convenient as having as electronic speed control. One thing that I did find inconvenient about the original design was that the spindle tended to coast for a good while after power was removed.  This could be unsafe and at times I used my hand to slow the chuck's rotation.   An upgrade was planned for the lathe which  included the following : 1. Add a more powerful motor. 2. Provide electronic speed control. 3. Provide electronic braking.   The upgrade was accomplished by replacing the 400 watt, single-phase motor with a 750 watt, three-phase motor.  The new motor to be driven by a motor controller which would provide for electronic speed control, thus ending the need to shift the belt to different pulley positions.   Also, the motor controller would provide for electronic braking, thus greatly reducing coasting.  And, of course the new motor would supply considerably more power. The motor controller is a sophisticated electrical device, but basically it provides for motor speed control by supplying   variable frequency  power to the motor, under operator control.  And it provides for braking the motor by injecting a DC current after the AC power is removed.   For those interested in learning  more about the motor controller, the manufacturer is YASKAWA, and the model name is  "VS mini."  The web site is - http://www.yaskawa.com/site/Products.nsf/products/Industrial%20AC%20Drives~VSmini.html As shown below a new pulley was made to accommodate the larger shaft of the more powerful  motor.

	1.  Making the pulley for the new, 750 watt motor. The pulley blank  is cast iron - 140 mm diameter, 15 mm thick. A boss was made beforehand from cast iron and is attached to the back of the pulley blank.  The boss has been bored to accept the motor shaft.
	2.  Cutting  the second pulley groove.   The finished  pulley is 15 mm thick with grooves to accommodate a  4.2 mm wide belt.
	3. The L-shaped motor-mounting plate is shown in the foreground.
	4.  New motor -- 750 watt, three phase --  mounted on plate.
	5.  Close-up of new motor pulley and drive belt.  The pulley has been painted black to retard rusting and is held in place on the motor shaft with a set-screw. Normally, only electronic control is used to vary the speed of the lathe.  But the two-step pulley was included for the sometimes needed high-torque situations.
	6.  Control panel includes a readout of the frequency of the motor controller, proportional to the lathe spindle RPM.
	7.  The center unit is a step-up transformer used to supply the lathe  motor controller (VS mini), right side.   The milling machine's  motor controller is located on the left side.