Can You Use A Bench Grinder To Sand Wood? Here's What We Found

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A quick look at the bench grinder in your shop or garage may be enough to discourage you from trying to use it to sand wood. For one thing, the work "table" — the surface that supports work while grinding — is too small to support large pieces of wood, and the edge of the grinding wheel is too narrow to spread out the grinding action. Moreover, the grit on a grinding wheel is fine enough to get clogged with sawdust — a combustible material – and frictional forces can ignite it. 

That doesn't necessarily mean you can't use your bench grinder to sand and shape wood, though. One way is to replace your grinding wheel with a flap wheel, and another is to convert your bench grinder to a belt sander. You can buy a conversion kit, or you can DIY the conversion.

Woodworkers use flap wheels with a drill or angle grinder to sand aggressively and in tight places, and you can install one on a bench grinder. A flap wheel is not the same thing as a flap disc, which has shorter flaps and tends to leave deeper scratches. Even with longer flaps, a flap wheel is an aggressive tool for sanding wood, so it's best to set the grinder to the lowest possible speed. Standard bench grinders rotate at a speed around 3,500 rpm, but a variable- or low-speed model can spin at around 1,725 rpm, which is a safer speed for wood.

If you really want to use your bench grinder to sand wood, the safest way to do it is to convert it to a sanding machine, and an easy way to do it is to purchase a conversion kit. The KFMK 2"x 36" Belt Sander Attachment for Bench Grinder, available on Amazon for $109, replaces the grinding wheel with a device that includes an adjustable-angle sanding belt and a sanding disc. The belt is useful for sanding flat surfaces, while the disc is best for shaping, smoothing, and rounding wood and metal pieces. The three kit models available all accept 2-inch belts and work with 6- to 10-inch grinders, depending on the model.

If a conversion kit is beyond your budget, you can take a tip from YouTuber Mark Susak and do the conversion for under $5, using scrap wood. His idea is simply to replace the grinding wheels with wooden discs made from plywood, to which he has glued some Velcro to hold the sanding discs. He made the wooden discs to fit the grinder, and the sanding discs he bought were the same diameter. He also built a sturdy wooden table to support the work he was sanding. 

Whenever using a bench grinder, it's important to work safely, whether you're grinding metal or sanding wood. Always wear eye protection, and don't wear gloves or any loose clothing that could get caught in the machine while the disc is spinning.