Most of my wedges, however, are born on the table saw because it is fast and, contrary to what some think, safe. Vise racking stop: Instead of spacers, I use a wedge with a lid to support the open end of the vise to keep it from racking. If it’s a good painting it may be worth the effort, and it could be a learning experience to practice re-stretching.

Mitre clamping jig: When gluing up picture frames or mitred moulding pieces, I reach for some wedges and the mitre clamping jig. It is good practice to try to get your bars to spread apart a bit before you start tapping in your wedges, rather then just using the wedges themselves to push the bars apart. Often a couple of millimetres is all it takes to make a loose canvas taut again, or pull a sag out of a corner. Best practice is that you should do all the movement of the bars by pulling and tapping on the bars to expand them and only inserting the wedges after you have expanded the frame.Due to our machining capabilities we are able to cut hardwood wedges to any size and specification required. They can easily be made tauter with corner tightening wedges, which expand the mitred corner of the bars slightly, enlarging the frame by a millimetre or so. You might try first just to re-stretch the the 1/4 of the painting that has the problem, it might be enough. After hearing a few experienced artists say they just threw their wedges away and later hearing them wonder about the best way to tighten up a slightly sagging canvas, I decided maybe the humble canvas wedge needed some clarification.

I came up with a cutting jig that is unlike most wedge-ripping jigs; it is adjustable to make wedges of different slopes and sizes on the table saw. But I find that on all canvases but especially on large canvases, I get a better tension if I hammer on the centre of the bar with a block of wood against the bar and then tap the wedges in.I used to insert my wedges parallel because it looks tidier, but now I prefer it so that the wedges are angled out toward the centre of the canvas, they seem to work a bit better.