How to cut and clamp a mitered frame
There's no substitute for accuracy when cutting frame pieces. Let us show you the way to tight miters.
Another typical woodworking clamp-up is a mitered assembly such as a simple picture frame. You can apply the cutting and clamping techniques described here to other projects, such as mitered boxes. The only significant difference is that in box construction you use two or more band clamps.
Mitered frames require eight cuts, and any inaccuracy quickly multiplies into an unsightly gap. That's why accurate cutting is the key to your success. A mitered frame looks deceptively simple, but several things can go wrong. With a little patience, you can cut miters with deadly accuracy.
To ensure success, we used a simple homemade tablesaw miter jig to cut the miters as shown in the photo, above right, (see "10 Quick-and-Easy Scrap wood Jigs" in the December 1995 issue, page 52, for jig plans). Make test cuts in scrapwood until you get the angle right. If the corners of your test frame do not close up neatly, make an adjustment to only one of the miter fences if the error is less than 1° or 2°. Then, recut just one miter on each piece: all right- or left-hand cuts. This is half the work of adjusting both cuts, and the slight difference in the length of the miter won't show.
Dry-clamp the frame pieces, using a band clamp with metal or plastic corners as shown in the photo, below right. Gather the other items you will need: glue, rags, water bucket, and putty knife.
Spread a thin film of glue on each of the miters. Assemble the frame on a flat surface and carefully check it for flatness as you tighten the clamp. If you need to adjust the pieces, back off the pressure rather than trying to move the parts under tension. Avoid excessive pressure, which can crush the outer corners of the frame. Follow the glue-removal and drying instructions as described in the final two paragraphs of the previous section.
For more in-depth information on gluing and clamping, visit our Gluing and Clamping section in the WOOD Store.