Variable vs. Fixed Speed: A fixed-speed machine, is set at 1625 RPM, while a variable speed version is adjustable from 1725 RPM to zero by just turning a knob. If the machine is going into a production shop and will be used for only a single purpose, a fixed-speed model is probably the best choice.
Grit Size: For rough grinding, an 80 or 100 grit is most popular and for smoothing a 400 or 600 grit. The 100 and 400 are the most popular combination. Prepolish and final polish pads are also available from Glastar which makes this machine a complete beveling station
Motor: The B4 is designed for production. The motor choices are the very best available. The fixed-speed motor is a Fasco 1/3HP and the variable-speed motor is a RAE 1/3HP. The electronic speed control has current limiting to protect the motor and control. The base plate is 3/16" thick stee. Every aspect of this grinder is over-designed to create a machine that will last and be trouble-free
1. Magnetic Disc Holder: Grinding discs are held in place magnetically. This unique mounting arangement allows use of the total grinding surface without being concerned about the work piece striking a mounting screw. It takes only 2 or 3 seconds to change the discs.
2. Motors: Both 1/3HP motors are "industrial" quality, and the variable-speed is a permanent-magnet motor
3. Splash Guard: This removable rubber guard completely eliminates spray. Clips are provided to retract the guard at two points so that long pieces can be ground
4. Coolant: For applying coolant, there is an adjustable gooseneck, valve and 1/4" compression fitting. This flexible gooseneck makes it very easy to direct a heavy stream of coolant to any area of the disc. There is also an 8' x 5/8" drain line included
5. Housing: This 3/16" thic, molded polyethylene part is an exceptionally tough material which will not rust
6. Base: A 3/16" thick steel plate forms the base to which everything is mounted
7. Speed Control: The electronic control for the variable speed motor produces a constant torque and includes current limiting to protect both the motor and the control. By changing the dial, the shaft speed is continuously variable between 0 and 1725 RPM
8. Pump Receptacle: The on/off switch in the front energizes both the motor and this receptacle. Therefore, when the machine is turned on or off, the coolant pump is as well