Four precision tools from a quarter sheet of plastic
Synopsis: This article shows how to make unusually sized squares you can’t find at stores or through catalogs. Gary Williams chose to make four different-sized squares from plastic so they would remain stable in variable humidity levels. A carbide-tipped combination blade will cut the acrylic. Basic construction plans and tips for assembling the parts to ensure that they are accurate are included.
A good square is an indispensable tool in the shop. So it makes sense to have several of them within easy reach of your workbench. For checking small parts, a 2-in. machinist’s square is a good choice. As parts get bigger, a 6-in. try square or 12-in. combination square is nice to have. And for larger parts, a framing square comes in handy.
But there can be a need for a shop square that’s sized somewhere between a combination square and a framing square. For an especially big project, like a cupboard, it would be handy to have a shop square that’s even bigger than a framing square.
Unfortunately, you can’t run to the hardware store to get such odd-sized shop squares. And you won’t find them in a mail-order catalog or at any nearby woodworking store. So I decided to make my own. That way I could size the shop squares to suit my needs to a tee.
Just one word: plastics
To be of any real value, a shop square needs to be dead accurate. So when making one, it’s best to use a stable material that won’t warp when the relative humidity starts changing. I ended up choosing acrylic plastic sheet, a product sold under trade names such as Plexiglas and Lucite.
Don’t worry if you haven’t cut acrylic sheet before. A sharp, 60- tooth, carbide-tipped combination blade does a nice job. The acrylic colors you’re most likely to find locally are white or clear but more interesting colors are available from suppliers like Ridout Plastics (800-542-6325). Ridout will ship you a 2-ft. by 4-ft. piece, which provides more than enough material to make the four squares shown on p. 69. You can also order the acrylic sheet on-line at www.ridoutplastics.com.
You’ll also need to order special glue for acrylic plastic. The easiest to use is a water-thin product called Weld-On No. 3. It’s used with a squeeze bottle that has a needle applicator and is drawn into the joint after clamping.
From Fine Woodworking #148
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