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Using Bench and Portable Grinders

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Bench and Portable Grinders

The grinding process consists of removing material from the workpiece by the use of a rotating wheel that has a surface composed of abrasive grains.

A grinding machine is a machine tool used for grinding, which is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation. Grinding practice is a large and diverse area of manufacturing and toolmaking. It can produce very fine finishes and very accurate dimensions.

General Grinder Precautions:
Stationary bench grinders and portable grinders basically remove material by contact with an abrasive wheel or disc, wire wheel brushes and buffing wheels. There are safety precautions that apply to both type grinders and other specific recommendations that apply to specialized grinding operations.

Before operating a grinder compare the date on the nameplate
with the voltage source and be sure the voltage and frequency
are compatible.

Remove material or debris from the area that might be ignited bysparks. Be sure others are not in the path of the sparks or debris.


Keep a properly charged fire extinguisher available.

Always wear safety goggles or safety glasses with side shields
complying with current national standards and a full face shield when needed. Use a dust mask in dusty work conditions. Wear hearing protection during extended periods of operation.

Do not wear gloves, loose clothing, jewelry or dangling objects
that may catch in rotating parts or accessories. Tie back
long hair.

Your work area should have adequate, shadow free lighting.

Maintain proper footing and balance. Never attempt to grind in an awkward position. A portable grinder can kick and glance off the work if not properly controlled.

Always disconnect the tool from the power source before installing or changing wheels or discs. Use only those wheels and discs marked with a rated speed that is at least as high as or above the speed rating on the nameplate of the tool. Don't use an unmarked wheel.

Handle or store discs and wheels carefully to prevent damage
or cracking.

Mount wheels and discs in the manner described and with the
hardware (flanges, nuts, and blotters) provided or recommendedby the manufacturer of the tool, disc or wheel, in the owner/operators manual.

Be careful not to over-tighten the spindle nut. Too much pressure will deform the flanges and stress the wheel. Never operate a grinder without the proper guard in place.

After mounting a wheel or brush and replacing the guard, stand tothe side and allow a one minute run-up at no load to test integrity of the wheel. Your grinder should come up to full speed each time before you contact the work piece.

Do not apply excessive pressure to the wheel or disc that will stress the wheel, overheat the work piece and reduce your control.

Bench Grinders: Safety eye shields provided with bench grinders must always be used in addition to operator eye protection.

Tool rests and spark guards are adjustable to compensate for wheel wear. They must be reset when a new wheel is installed or after a wheel has been worn or dressed. The distance between the spark guard and the wheel should be within 1/16 in. The tool rest should be slightly below the center of the wheel with 1/8 in. or less clearance from the wheel. This prevents accidental jamming between
tool rest and the wheel.

Grinding wheels should be tested before mounting. Tap the wheel lightly with a nonmetallic implement such as the handle of a screwdriver. If it produces a ringing sound, it is in good condition. If it sounds dull, replace the wheel. DO NOT USE A CRACKED WHEEL.


Check your owner/operators manual for proper procedures.

Grinding wheels should be trued and dressed when worn out of round, or the surface face is clogged or worn smooth. This provides a clean sharp grinding surface and rebalancing of the wheel.

New wheels should be balanced by dressing and truing to eliminate vibration and possible mishap. Check your owner/operators manual.


Don't operate a grinder unless you are certain the grinder, its base and/or pedestal are securely mounted.

Use only the type and size flanges provided with the grinder.

PORTABLE GRINDER: If you drop a portable grinder or a wheel,
inspect carefully for damage.

Portable straight grinders should use only high strength,
bonded wheels. Position this type grinder away from you and allow to run for one minute before contacting work.

Tuck point grinders are a variation of straight grinders and are
equipped with reinforced abrasive discs and the appropriate guard, and by purpose engage in very dusty work. A dust mask and face shield in addition to safety glasses with side shields is highly recommended. Maintain firm control of the tool. Never overreach.


Carefully maintain balance.

Do not allow the grinding wheel to bend, pinch or twist in the cut.


Kickback may result.

Angle grinders are primarily used with reinforced abrasive
discs or wire cup brushes for the proper wheel and guard
combination is critical and must follow the manufacturer's
recommendations contained in the owner/operator manual.

Many angle grinders are equipped with guards that may be mounted with the opening in a variety of positions. Take care to position the guard to provide you with maximum protections. Many angle grinders may be converted for use as sanders. When guards are removed for sanding operations, it is essential that guards be replaced before
again being used for grinding.

Hold an angle grinder firmly with both hands to avoid recoil caused by jamming or wedging.