Besides the efficiency of the Variable Frequency Drive (VFD) unit, being able to select a specific speed is advantageous for selecting the best grinding rate for particular blades, such as small trimmers, to minimize heat distortion. A twist-knob potentiometer with a 1-10 scale is used to set and adjust the speed. The VFD can be programmed to set the rate of acceleration and deceleration. The electronic brake minimizes the need for a mechanical brake to stop or slow down the disc.

The VFD model lowers the amperage draw down to 6 amps on start up and 1 amp running. This means a mobile sharpener can run our full sized machine with just a 1000 watt inverter, granted that it is a quality brand. The unit will function on both modified and true sine wave power. We recommend at least a 1500 watt inverter to allow for other items to be on at the same time such as lights, etc.

In comparison, our single speed machines, using a capacitor-start 1/2 hp motor, draws 34 to 37 amps for 3 to 4 seconds on start up and runs on 7 amps. This requires a 5000 watt inverter or larger to operate.

Cleaning the disc, applying the lapping solution, and recharging with grit is easier when the best speed can be set and it stays steady for the duration of each operation.

As with all the motors we use the units are taken completely apart, the armatures dynamically balanced, and the bearings checked and preloaded for the vertical load application of a clipper hone. Since electric motors are typically designed to bear a horizontal load as with a belt and pulley, or be used inverted as with a pump application, bearing rattle and noise and premature failure and vibration can ensue if the the bearings are not retained and preloaded in the same direction as the down load of the disc.