A bench grinder is an essential tool for both professional and hobbyist woodworkers. Its versatility, ease of use and minimal need for safety makes it a great addition to any woodworker’s tool kit.
This grinding machine is used to drive abrasive wheels which sharpen cutting tools like chisels, drill bits, tool bits and gouges. The wheels are interchanged to enhance the machine’s functionality. As such, you can clean, sharpen, polish, buff and shape wooden or metal objects using a bench grinder.
Here’s an in-depth overview of the functions of a bench grinder:
Sharpen Tools
The bench grinder is your go-to equipment for sharpening tools that have grown dull after prolonged use. You need to use the right grit size depending on the workpiece. Wheels with 36-grit are suitable for sharpening gardening tools, while 60-grit wheels are designed for grinding plane irons and chisels. 80-100 grit wheels are ideal for more delicate jobs like shaping metal parts.
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Be sure to choose an appropriate grit type to sharpen the tool. Aluminium oxide grit wheels are suitable for sharpening workpieces made of low and high carbon steel while pink and white types are ideal for hard steel materials. Use silicon carbide grit wheels when sharpening softer metals.
Ensure the machine has a tool rest as it keeps the tool in place when sharpening. It should be 2-3 mm away from the wheel to prevent the workpiece from slipping down between the tool rest and the wheel. If sharpening a chisel hold it firmly using both hands while pushing the blade against the grinder slowly.
Slant it slightly up or down depending on the construction of the blade. This up and down motion enables the machine to grind on the tool without overdoing it. Be sure to keep a tray of water close to cool the blade.
Shaping Wood
Apart from the apparent sharpening function, a bench grinder is used to shape pieces of wood pieces. The machine shapes severely deformed metal pieces using rough stones on the wheel edge. A bench grinder is also ideal for shaping metal workpieces before fitting them on other parts or welding.
When shaping pieces of wood, you need to use a back and forth motion as if grinding off part of the wood. The machine also makes it easy to smoothen wood surfaces instead of using a chisel.
Buffing
A bench grinder is also used to buff wood pieces, but a different set of wheels is required for this task. You will also need a buffing compound to increase the effectiveness of the grinding wheel. Buffing compounds are available in different colors and types each designed for different uses. Rough compounds are ideal for removing scratches from metal surfaces while mild ones are used to provide a smooth, shining finish on a tool.
The black emery compound is the most common and is used to remove small pits, scratches, paint, plating and lacquer from metal surfaces. It comes in handy when you have involving jobs as it saves you hours of removing deep scratches.
The greystar compound is excellent for a range of applications. It is best used on stainless steel materials along with more rigid buffing wheels. If buffing softer metals like aluminum, brass and copper use the brown Tripoli compound. It is also used on wood surfaces giving them a glossy finish.
A lower speed is ideal for the buffing process (usually 1725 RPM), and you need to keep moving the workpiece to avoid overheating. Also, when buffing wood apply a little wax to make the job easier and more efficient. Allow it to dry before buffering the wooden piece.
Remove Rust from Tools
For this task, you need to replace one of the grinding wheels with a wire wheel. Be sure to buy a high-quality wire wheel as cheap ones have wire bristles that fly off when the machine is operating at high speed. Wire wheels come in three varieties: fine, medium and coarse. Fine wire wheels are suitable for restoration of metal pieces, but for rust removal you need braided or knotted wire wheels.
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The wheels are also made of different materials including stainless steel, brass and mild steel. Stainless steel wire wheels are suitable for materials made of the same material while mild stainless steel wire wheels are ideal for restoring tools made of softer metal. Since the wire wheel throws off parts and debris, it is essential to wear safety glasses.
You also need to reduce the speed of the grinder since rust is not set deep into the surface. Reduced speed keeps you from grinding too much of the material from the surface. You should also consider performing preventive measures to prevent rust buildup. You can store them in a cool, dry place and toss some silica sachets to keep them from absorbing moisture.
