How to Use a Bench Grinder
A bench grinder is probably not a tool you’ll use every day. However, if it’s available and set up correctly, you’ll be surprised how often it comes in handy for everything from sharpening tools to rounding over thread ends on a cutoff bolt. We’ve assembled these tips to help you get the most out of your grinder.
Keep a container of water handy
To avoid ruining the edge of a tool by overheating, keep water nearby to cool the tool. A good technique is to move the tool once across the grinder for no more than a few seconds. Then dip it in the water. If the steel edge does overheat and turns color, grind the edge back to good steel and start over.
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Grind small objects safely
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Consider a low-speed grinder for sharpening
Another advantage of a low-speed grinder ($100 to $150) is that this type typically includes friable white grinder wheels, which do a better job of sharpening than the gray grinder wheels usually included with high-speed grinders.
Dress wheels frequently
To use a dressing tool like this, start the grinder and wait for it to reach full speed. Then press the diamond wheel dresser against the spinning wheel, holding it perpendicular to the face of the wheel. Be sure to wear a good-quality dust mask. The fine aluminum oxide dust is very bad for your lungs. Draw a pencil line on the wheel before you start to help you gauge when you’ve removed enough material from the wheel. Dress the wheel just until the pencil line disappears.
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Watch for the sparks to come over the top
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Make an Angle Gauge
1. MARK THE ANGLE ON CARDBOARD
Align the center mark on the protractor with the top edge of the cardboard. Then turn the protractor until the desired angle is also aligned with the top edge. Draw a line along the protractor to mark the angle. Don’t forget to label the angle. Cut along the line to create the gauge.
2. ADJUST THE TOOL REST
Set the cardboard on the tool rest and adjust the angle of the tool rest until the wheel contacts the center of the angled portion of the cardboard gauge.
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Upgrade the tool rest
There are several variations, some made for specific tasks like sharpening lathe turning tools. This Veritas model has two adjustments for positioning and aligning the tool rest, and levers for easy tightening. You can also buy an attachment that holds chisels or plane irons.
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Make your grinder portable
The stand is built from two 12 x 16-in. pieces of 3/4-in. plywood separated by two 4 x 12-in. uprights. We used two 5/16-in. bolts with washers and nuts to attach the grinder, leaving enough space in front of the grinder to mount a stand-alone tool rest.
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Set up a polishing station
To use the polishing wheel, hold the stick against the buffing wheel as it spins to transfer some polishing compound to the wheel. Then hold the object lightly against the wheel and let the compound polish the surface.
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• Turn the grinder on and stand aside until the wheels come to full speed. If there’s a problem, you won’t be in the path of flying debris.
• Inspect grinder wheels for cracks or damage. Before you install a new wheel, suspend it by a screwdriver through the center hole. Tap the wheel lightly with the plastic handle of another screwdriver. The wheel should ring. If you hear a dull thud instead, the wheel is probably cracked and should not be used.
• When you install a wheel, don’t overtighten the nut. Just snug it up. Overtightening could crack the wheel.
• Keep the shrouds and spark shields in place. And maintain a 1/8-in. or less gap between the tool rest and the grinding wheel.
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