How to Cut Precise Angles with a Miter Box

A miter box helps you to make straight, correctly angled cuts. You can think of it as being like training wheels on a bicycle.

In your local retailer, you may see a miter box and a tenon saw sold in one package. However, in the combination that I tested, the saw was of poor quality. Buying one separately costs extra, but is worthwhile. Look for a tenon saw, back saw, or miter saw with hardened teeth, greatly reducing cutting effort. Stanley FatMax 17-202 is ideal.

CLAMPING YOUR WORK

Many people will tell you that you can saw wood by placing it on a sawhorse and holding it there with your foot. I’ve worked this way myself, but accuracy is difficult to achieve when you are standing on one leg, anchoring the wood with your other leg, and working at arm’s length.

For the projects in my new book Make: Tools, you will need to make precise cuts. The best way to achieve this is to clamp your work to a solid bench or table.

A trigger clamp is the easiest to use, as shown in Figure 1. It is also known as a bar clamp. The small metal lever is the trigger, which releases the jaw of the clamp, allowing it to slide up or down the bar. Let go of the trigger, and the large black plastic lever closes the jaws of the clamp when you squeeze it repeatedly.

If you are using a miter box, Figure 2 shows how to clamp it to stop it from jumping around. Anytime you are not using a miter box, you can apply a clamp directly to the wood that you’re working on.

CUTTING A USABLE LENGTH

Long pieces of wood are difficult to control precisely. If your piece of wood is longer than 36″, reduce it to about 36″ or slightly less.

Place the wood in the miter box — I used a square dowel in Figure 3.

The miter box that I have is equipped with a couple of pegs, described as “cams.” You insert a peg in a hole close to the wood and turn it to lock the wood in place, as shown in Figure 4.

If your miter box doesn’t have this feature, you can hold the wood in the miter box with your left hand, as shown in Figure 5. (If you are left-handed, hold it with your right hand.) Be careful not to put your hand too close to the saw. I do recommend that you wear work gloves while using a saw.

Beginning a cut can be difficult, because the saw tends to dig in. Draw the saw toward you a few times, to create a shallow groove in the wood. Now when you push the saw, it should cut more easily. If you still have trouble, drag the saw toward you a few more times. Keep your free hand at least 4″ away from the saw blade, as shown in Figure 6.

Don’t press too hard when you are cutting the wood. You shouldn’t be fighting a battle. The saw should do most of the work for you.

YOUR FIRST MITERING EXPERIENCE

The best way to learn is by practicing, so I suggest you use some square dowel to make a small frame measuring 6″×5″ along the outside edges.

First, draw two vertical lines 6″ apart on your dowel (Figure A). (Picture frames are usually sized by their inside dimensions, so that you know if your picture will fit, but for this project it’s easier to start with the outside.)

In Figure B, the dowel is in the miter box, and the saw is in the slots angled at 45°. A cam could be used to hold the wood in place, but I assume you may not have one, as many boxes are supplied without them. You can use your thumb to hold the wood, but keep your fingers away from the saw blade. Cut carefully down the outside of the vertical pencil mark, while pressing with your thumb as hard as you can, as the saw will tend to push the wood around.

Check the length of your work, as in Figure C. You may be tempted to smooth the fuzzy sawn edges with some sandpaper, but sanding will tend to spoil the accuracy of the cut.

Now the good news: cutting your first piece at 45° automatically creates a 45° angle on the remainder of the dowel, so that it can be used for the next section of the frame. This is shown in Figure D. Just make a new measurement, and cut that section, turn it around to fit the first, and continue until you have a total of 4 (Figure E).

Check that the angles fit correctly. To secure the corners, use carpenter’s glue and wrap a ratchet strap around the frame, or use heavy nylon rope with a slip knot. Tighten well, wipe away glue that squeezes out, and let dry.