Model B4 - 8" Diamond Disc Grinder with Magnetic Holder

Model B4 - 8" Diamond Disc Grinder with Magnetic Holder

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Diamond grinding is the fastest and most economical way to grind glass or stone. Because it is so much faster than any other method, it pays for itself in a very short time. Now, it is possible to grind and polish all on one machine and change media in 2 or 3 seconds.

We feel that if the B4 is the only grinder in your shop, it should be as versatile as possible. With the variable speed motor, lapidary shops can take advantage of the different speeds for different materials.


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

Optional Accessories

Glastar stocks a very large choice of diamond discs and polishing pads. Create the combination that works best for your needs.

An industrial pump is available so that coolant can be recirculated over the diamonds which will improve life by 10-15%


Drive Shaft
Mounting (Steel Disc Only) Magnetic Hub with 1/2" Centering Pin
Rotation Counter Clockwise
Type Direct Drive
Fixed Speed Motor
Power 1/3 HP
Voltage @ 50 or 60 Hz 115V or 230V
Current @ 115V 3.6A
Current @ 230V 1.8A
Speed @ 60 Hz 1625 RPM
Speed @ 50 Hz 1350 RPM
Breakdown Torque 26oz-ft
Type Permanent Split Capacitor
Bearings Sealed Ball Bearings
Manufacturer Fasco
Variable Speed Motor
Power 1/3 HP
Voltage @ 50 or 60 Hz 115V or 230V
Current @ 115V or 230V 1.25A
Speed @ 50 or 60Hz 0 to 1725 RPM
Torque @ 1250 RPM 23oz-ft
Type Permanent Magnet Electronically Controlled
Bearings Sealed Ball Bearings
Manufacturer RAE
Weight 35 Lbs
Size 13" X 15" 1/4 X 9 1/2" High Including Plumbing


B4R DISC DRIVE (8" magnetic hub)
1/3 HP Fixed Speed 115V, 60Hz P33367 $780.00
1/3 HP Fixed Speed 230V, 50Hz P33368 $820.00
1/3 HP Variable Speed 115V, 60Hz P33369 $1,020.00
1/3 HP Variable Speed 230V, 50/60Hz P33370 $1,075.00
Crystal Repair Head 600 grit P34131 194.00
Model B4RV
For Grinding / Polishing Straight edges, and outside curves
Model B4R Variable Speed Disc Grinder P33369 $1,020.00
8" 120 Grit Diamond Roughing Pad P34002 $122.50
8" 400 Grit Diamond Smoothing Pad P34004 $88.75
8" Diamond Resin Prepolish Pad P33925 $52.50
8" Polyester Felt polish Pad P34181-02 $23.25
8" steel Disc 4@ $19.00 ea P33986 $23.25
Total $1,383.00