For any square to be of use as a layout or marking tool it must, of course, be square. The most dimensionally stable material to use for this project would be a manufactured sheet goods such as MDF or Baltic Birch plywood.

This version is made of three different species: the arm is wenge, the edge guide is makore and the straight surfaces have been edge-banded with quarter-sawn white oak. Not only does the while oak provide a durable long lasting guide surface, but it also contrasts nicely with the other two species.

Square Stable Stock

While you can choose from a wide range of wood to use in your square, it’s important to select dimensionally stable wood, preferably quarter-sawn, else your square may be, seasonally out-of-square. When milling your stock accuracy is important – you want all of the parts to be flat and square.

It is easier, as well as safer, to make two squares at once – this lets you work with larger pieces when preparing the initial stock on the jointer and thickness planer. The dimensions in the materials list reflect this. Of course, you can easily modify the dimensions to suit the kind of work you do. You might want to make one large square for use on cabinetry and sheet goods, and a smaller one that would be more manageable on your workbench.

• Use a jointer and thickness planer to prepare your stock. For the square to be of any use, it will need to be accurate, so be sure to begin with flat, square stock.
• Prepare the pieces for the arm (A), edge guide (B) and the edge banding (C, D). Check them with an engineers’ square to be sure the sides are 90º to both faces.
• Glue the two pieces of edge banding to the arm and set it aside to cure. The banding blanks should be just a little bit larger than the edge they will be glued to; it’s not critical to center the banding on the edge, but it must cover the whole piece.
• Decide which side of the edge guide will get the banding, and glue it in place. Be sure it covers the entire edge and doesn’t move out of place as you apply clamping pressure.
• After the glue has set, remove the clamps from the pieces and use a fine hand saw to trim the edge banding back on the ends. If there is an overhang here, it is likely that your router bit will catch it and tear the edge out at the end of the cut.
• Set up a piloted flush trimming bit in your router table and trim the banding flush on the arm and edge guide blanks.
• Use your band saw to re-saw the blank for the arm. You will end up with two pieces, each slightly less than ½” thick. As necessary, re-joint each piece and then thickness plane them to ⅜”.
• Square up the edges with a light pass on the jointer.
• Thickness plane the edge guide blank to a finished thickness of ⅝”.
• Use a cross cut sled on your table saw to cut the two arms to the finished length of 10 ½” (see ‘Cross Cut Sled’, Feb/Mar ‘07, Issue #47).
• As the cross cut sled has already been optimized for making accurate 90º cuts, it makes sense to use this jig to cut the dado for the arm. Measure the width of the arm and set a couple of end stops on the back fence of the cross cut sled. Set these to limit the cut to slightly less than the required width.
• Raise the blade to take a ¼” cut. Cut the dado using multiple passes over the blade.
• Place the edge guide on the sled, against one of the end stops. Loosen the other stop and slide about ten pieces of paper between the end stop and the part. Tighten up the end stop, remove a piece of paper and make the cut. Test fit the arm and repeat this until the arm fits without any play.
• Pencil a pleasing curve onto the top of the edge guide and cut it out with a band saw. Use sandpaper to smooth the curve.
• Set up a 45º chamfer bit in your router table. Chamfer only top edges of arm. Do the ends first and the long grain cuts will remove any tear out from the first cuts.
• Sand all of the parts and apply a coat of Watco Natural Oil. Be sure not to get any finish in the area to be glued.
• To make gluing up this project easier, build a little jig using some melamine offcuts. Cut two pieces of melamine, one about 12″ square and the other about 4″ square. Be absolutely certain that the corners on the smaller square are exactly 90º. Screw the smaller square to the larger one, and then use this to align the arm and edge guide during the glue-up.
• Apply glue to the dado and use the jig to align the two pieces. Clamp the edge guide to the jig, and then apply clamps to hold the arm in place until the glue cures.
• After the glue has cured, give everything another coat of Watco Oil and then follow this up with a few coats of paste wax.

These layout squares are sure to be some of the most useful accessories in your shop. Make some in several lengths and you’ll always find a use for them, from laying out full size drawings to a fast and accurate clamp down fence for your router.