Understanding Finishing Sanders

A finishing sander is a power tool used to deliver a smooth, fine finish to materials. Generally called a block sander because of their square shape, these sanders provide a close and smooth finish while also delivering optimized corner access. Because the sander is square, finishing corners is far easier than with a sander with a circular base (an orbital sander, for example). Block sanders use standard size sandpaper sheets; this is advantageous for several reasons. Standard sandpaper is much easier to find and replace, and it doesn’t require any trimming or shaping; this can save craftsmen both time and money. Random-orbit sanders are often lumped into the finishing sander category. They are smooth and quicker (a little rougher) than a block sander, but end results are not quite so polished. Orbital sanders require special circular sandpaper sheets, but the tool is generally quite inexpensive, so sandpaper costs are almost negligible. Ultimately, though it may take a bit more time to finish with a block sander, it removes less material with each pass and generally results in a much better, smoother and finer finish.

Maintaining finishing sanders is generally simple and straight forward. Block sanders and random orbit sanders each use backing pads to support their sandpaper sheets. As the tool is used the pad will gradually wear down until it needs to be replaced. It’s good practice to check the pad every time you change the sandpaper. These backing pads are fairly simple and inexpensive to replace, so don’t risk the quality of your materials or finish because of a worn out backing pad. You should also blow out the interior of the tool when changing the pad; dust and debris is the power tool’s nemesis. As with all power tools, it is important to keep finishing sanders clean. A great deal of dust and debris is created when sanding, so it’s important to blow out the tool after every use – periodically, at least. Taking good care of power tools isn’t hard, so although these sanders are less expensive than some of the tools in the shop, they save craftsmen a lot of time and energy and deserve the same attention as our miter saws and routers.

With all sanders it’s important to let the tool do most of the work for you. Don’t push or pressure the tool too hard, this can result in an uneven finish or gnarly divots in the material. Rushing a finish job can quickly become a disaster, so be cautious and work with the rhythm of the tool. It takes only one moment to make a mistake while sanding, and hours to repair it. Remember to keep your sanders clean, and to appreciate the smooth and precise results a block sander will bring to your finished products.

As a student at the Univ. of Utah, Mallory Kramer is currently earning an English degree. Three years ago she joined M&M Tool adding to their over 150 years combined experience; she specializes in tool parts & web communications. For over 60 years M&M Tool has provided the best service to the tool industry with parts, sales, & service to expert woodworking products, tools, & machinery. Visit M&M Tool’s forum for woodworking articles & advice.

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