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Winter 2013-2014

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Shed Doors 6: Hinge Mortises


Last summer, I added a small shed to my old garage. I hung some temporary plywood doors, and built the real doors in the shop here at American Woodworker. Here are links to the first five parts of the story: Shed Doors 1 and Shed Doors 2 and Shed Doors 3 and Shed Doors 4 and Shed Doors 5.

The doors are ready to glue together, but first I have to cut mortises for the hinges. I chose to make the mortises by hand, the old-fashioned way. Is that a nutty thing to do? Well, we'll see.

The tools needed are pretty simple, and I have the pleasure to own some very nice ones:

A 6" Starrett square, my favorite layout tool;

A Tite-Mark marking gauge, which has a precise micro-adjust mechanism;

An old Greenlee 1-1/4" butt chisel;

An old Stanley Everlast 3/4" chisel (both of these chisels hold their edges quite well);

A Calvo brass mallet, which is beautifully balanced.

And last, a secret weapon, which I'll share with you later in this blog.

The first step is to mark one end of the mortise. I prefer to use an edge tool to score a line rather than draw a line with a pencil. A scored line is much more accurate. A marking knife would work, too, but I just use the corner of my chisel.

I mark the other end of the mortise with a pencil, though-about 1/8" shy of the hinge's length. I'll score an exact mark later.

I use the marking gauge to define the width of the mortise. It also makes a fine scored line.

Next, I establish a shoulder at the scored line. By paring towards the line at a shallow angle, I can pop out a small shaving. Then I stand the chisel up on the line, bevel towards the waste side, and strike it with the mallet to deepen the shoulder. Another paring cut makes the shoulder about 1/32" deep–good enough for now.

I do the same thing along the length of the mortise, paring at a shallow angle up to the scribed line.

Then I deepen the shoulder with a mallet blow on the wider chisel. A wide chisel really helps to ensure that the line stays straight, which is why an old-time carpenter would always have one in his tool kit.

The fastest way to remove the bulk of the waste is to make a series of closely-spaced cuts with the wide chisel. The bevel faces away from the waste, and the chisel is slightly slanted back. To get to this depth, I hit the chisel twice. On the second blow, the chip breaks off by itself. The whole operation goes very fast.

Here's the tool that's going to give the mortise a perfectly flat bottom: a router. A router without a plug. Hand routers are quite old, but this is a new one from Lee Valley. I've got a couple of old Stanleys, but this tool is better.

First, it has a depth stop, which the Stanleys don't have. (I'll show you how that works below.) And second, the cutter is much easier to sharpen. The Stanleys have a one-piece cutter, shaped like an L, which is tough to hone accurately. The Lee Valley cutter is actually two pieces: a cutter and a shaft. The cutter is screwed on to the end of the shaft. To hone the cutter, you just unscrew it and mount it in a device that makes it easier to hold. Now you have a unit that's as easy to sharpen as a chisel.

One thing about a hand router–you don't go for the final depth in one shot, the way you would with an electric router. With a hand router, you lower the cutter bit by bit, one shaving thickness at a time.

Here's the first pass. I'm just taking off the high spots of the rough surface left by the chisel.

For the next pass, I lower the cutter by turning the brass knob on top of the tool. The nut engages in a groove in the cutter's post, forcing it downwards. A quarter-turn of the nut lowers the cutter enough to take off another shaving. I shave the entire bottom of the mortise, staying within the shoulders I defined earlier, then lower the cutter again.

You keep doing this until you reach the final depth. There are two jam nuts on the threaded post, underneath the depth-of-cut adjusting nut. They automatically set the maximum depth of cut.

When I make the next mortise, I'll raise the cutter back up, and just keep lowering it until I bottom out on the jam nuts again. That's pretty slick. I'm not sure why the brains at Stanley didn't figure this out: I'm going to see if I can retrofit my old routers with similar jam nuts.

Once down to full depth, I place the hinge in the mortise and scribe the other end with the chisel. After chopping this shoulder, the mortise is done.

Here it is, a perfect fit, with square corners and a flat bottom. Start to finish, the whole job only took about 15 minutes. I'll grant you that an electric router would be faster, but not half as much fun. I wonder if John Henry felt the same way?

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