How to build a stretcher
My father built my stretchers for me for the first three years of my career. When he handed over the reins to me, he gave me just one piece of advice and I’ve found it to be indispensable. Be generous with your carpenter’s glue. He explained to me that it’s the glue that holds the wood together, not the nails or staples.
Tools: carpenter’s glue, stapler, measuring tape and marker, saw and miter box, sandpaper, square, hammer, finishing nails.
Materials: quarter round molding and 1 x 2 boards for the stretcher bars, wood paneling for the corner triangles.
The first step is to glue the quarter round molding to the 1 x 2 boards. I staple the molding in place and clamp it as well to be sure that the molding and board become a solid unit. I remove the staples (and clamps) once the glue is dry. In order to cure properly, board and molding must sit for at least two days before being cut up.
As the saying goes: measure twice, cut once! This is especially true when you’re using a miter box and saw powered by your own muscle. Once you have the stretcher bars at the right length, sand off the rough edges and remove the dust. Cut the corner triangles out of the wood paneling and prepare them by hammering two finishing nails half way into either side of the triangle.
Put glue (lots of it!) on the angled edge.
Square it up.
Put glue (more of it!) on the corner where the triangle will secure the joint.
Nestle the triangle in the corner and hammer it into place (it is easier to drive the nails in if they are already half way in place since the glue makes the triangle slide around under the hammer’s pressure).
Repeat the process with the other three corners, being sure to square them up each time. The stretcher must dry flat for at least twenty-four hours, and it should be allowed to cure for another two days before stretching the canvas on it.
If the stretcher you want to make is 36 inches or larger in both height and width, consider adding a stabilizing bar in the middle.