Making a try square is a good idea for anyone getting into woodworking with hand tools, as I am. In the process we’ll work on planing, hand cutting to the line, accurately scribing & chopping mortises with chisels. As a bonus to practicing these skills, we’ll end up with a tool while using up some scrap wood. It might seem like a bad idea to make a tool like this out of only wood, with seasonal movement and all, but the good thing about this is that; 1) it’s actually quick to check if the square isn’t square, 2) Its just as quick to fix and most importantly 3) it’ll be a tool that you made, that’ll later be used to make other things.

Step 1: Select and Prepare the Stock.

Like with all projects, we first select our stock. Any kind of hardwood I think is a good choice. The wood I’m using is from an old couch that was in my basement when I moved in. The couch was old and ratty so I took it apart and found some pretty nice wood in there. I think it’s oak, but my skills at identifying wood is lacking, but also what else would be in a crappy old couch? The bottom piece in the first photo will be the handle, and the top will be the blade (the part we run our pencil or marking knife along). With the wood I selected, I had to spend some time pulling out staples and nails.

After the staples and such were removed I cut the pieces to length. The longest piece for the blade I could get was about 8”, so I did the same with the handle. The blade of course is going to be thinner than the handle (mind ending up being about ⅓ of the width), so I had to resaw that piece. This is where I first went lazy. I could've used a hand saw to rip the blade, but decided to go with the band saw, which was actually not powerful enough to do that. That should’ve been a sign to use a hand tool but went with my table saw.

NOTE: This kind of cut is dangerous. Use any and all of your push sticks, feather boards, etc to keep your hands away from the blade. I set my fence to half the thickness of the piece (This was also my first mistake, I’ll show why later when we cut the mortise), and the height of the saw to a little over half the width of the wood. I cut this in two passes, flipping the piece over for the second cut, making sure to keep the same side as before on the fence. After they were ready to plane.

I don’t have a regular woodworking bench with bench dogs or end vises so I screwed two pieces of plywood at an angle and used scrap pieces as wedges to keep the workpiece in place. Because of the wedge’s direction the workpiece stays put as I work on it. To remove it I just pull it towards me and it’ll come right out. This is a good trick if you don’t have any other way of clamping and don’t mind screw holes in you benchtop. Though, this didn’t work for the blade because it was thinner than the wedges. I could’ve made a set of bench hooks, but I went the quick way and used my box planer. With the faces of the blade and handle flat I trimmed the edges square on both pieces with the table saw. A shooting board could’ve been used in place of that. Now we’re going to mark out the joinery.

Step 2: Marking Things Out.

For the joinery we are going to use a type of through double mortise & tenon, with the top tenon being more like a bridle joint. If cut properly, The two tenons will help keep it square when we assemble it. The top edge of the blade is going to stick out a bit above the top edge of the handle. You might want to keep those edges flush, but keep in mind that when we true up these squares, we’re going to be plane along that top edge, which would then be the end grain of the handle. I’m not saying don’t do it, just saying it’ll take longer and be trickier to true up the square.

To mark out the joints, you could measure the thickness of the blade and the length of it, etc, but I wanted to try and just use the marking gauge to put this together. As you’ll see, mine came out a little more messier than they should have, so maybe using the actual measurements is a better idea. Also the way I’m going to lay out the steps may not be the way I actually did them, but they’re the way they should’ve been done.

First I marked the length of the tenons by setting the scribe to the width of the handle. Next I gauged the widths of the tenons using an outside caliper like a divider. I eyeballed them to be about a third of the total width. Be sure to mark the waste piece to be cut out. It’s easy to get in the “flow” of work and cut out the wrong piece. I gauged the width of the blade, minus the top edge that will be above the handle. With that length I marked both sides of the handle (be sure to do that as these will be through mortises). This gave me the bottom line of the mortise. Next I tried to hold up the blade to the handle to gauge the thickness of the mortises, this is where actual measuring would’ve made this more accurate, or a marking gauge with two cutters. With the marking gauge set I marked both sides. Again holding up the blade to handle (and again, this wasn’t the best way to do this), I marked the widths of the bottom mortise. With it all marked up, put an “X” on the waste pieces.

Step 3: Choppin'

Cutting the waste in the double tenon is easy with a chisel and hand saw. With the blade in a vise I cut the sides of the tenon with a hand saw. Next with the piece flat on the bench we can start to cut the waste off. Line the chisel up at 90 degrees from the workpiece, the chisel edge a little bit away from the shoulder line, and give it a hit with your mallet. Next do the same thing, cutting at an angle towards the cut you just made. Flick away the wedge piece that’ll come out and flip it over to make the same cut on the other side. Keep making these series of cuts, flipping the piece over all the while. After the cut goes through, use finger pressure (if the chisel is sharp enough, you could continue with the mallet) to pare away the material until you make it to the baseline marked before.

Now to the mortises. This is where the mistake I made resawing the blade comes in. I have a mortise chisel I got from a second hand shop. It’s ⅜” wide which, as I realized after starting to cut the joint, is wider than the blade’s thickness. I should’ve paid more attention to that so then I could make sure that I had a chisel the right size. Using pieces that are the same sizes as your tools can help keep joints more accurate and saves time. So I had to use a regular ¼” chisel and make a lot more cuts than I would have with the other chisel.

The cuts for the mortises are like the cuts for the tenon, though we’ll start at the middle and cut into it in a “V” pattern. So place the chisel in the center, holding it perpendicular to the piece, and strike it with the hammer. Then cut into the same way at an angle towards that center cut, that makes the “V” shape. Repeat that series of cuts, going in deeper and wider, but don’t cut to either end of the mortise yet. Flip the piece over and repeat the cuts until you break through. Then start making straighter cuts towards the marked edges. For the top mortise we do basically do the same thing, but before that we can use hand saw to cut the edges. Now we can try and fit it.

Step 4: Fitting and Trying.

We might need to trim the tenons or straighten out the mortises (mine were way off, due to the bad scribing). You’ll see in the photos how off they were. To fix this, hopefully you won’t have to though, I chose to fit in some wedges. After it fits well we can glue it up. It might look like the way I clamped it pulls it out of square (it totally does), but that’s ok the next step fixes this.

Find a straight edge you can draw a line on with the square. Flip it over and line up the blade to the line you just drew. In my photo you can see there's a high spot at the far edge, The gap near the bottom is actually double the material that needs to be taken off. So don’t go too crazy with the plane. After making a few passes over the high spot, run one along the whole edge and do the test over with a new line. It might take a couple of tries, but it still only takes less than ten minutes. The same process should be done with the inside edge of the blade, and it will be tricky to get a plane in the corner, so you'll have to switch to a chisel.

Step 5: (Optional) Decorative Touches.

This next step is optional and just for decoration. Using a small compass I made with plans from John Heisz (he has a great Youtube channel), I drew a small curve on the bottom corner of the blade and cut it with my band saw. This is also a good time, though I did this earlier, to think about the handle’s profile. I chamfered my edges, you could do the same or round them over. Another nice touch would also be a groove right where your thumb would go.

Step 6: Finishing and Room for Improvement.

To finish, I did some light sanding, just to take down the sharp edges to prevent splinters. I wouldn’t make, at least the blade, too smooth. Then it might slide around as you try to mark a line, which is never fun. Finally I applied a few coats of tung oil.

Thats it, you’ve used tools to make another tool. I don’t think there’s anything better than that. Just be sure, every once in a while check for trueness the same way we did before and fix it the same way.

Now I want to go over some of the things I would change if I did this again, which I probably will.

First, I would pick a differ piece to use for the handle. The knot in it looked really nice after it was finished, but it also made it terrible to plane. The grain direction switches in the middle of the piece, so tearout was common. It also made it hard to straighten the back of the handle, so I can’t really use it to square the inside of a case with the outside edges of the square. A toothed plane or aggressive sanding could help.
I would make sure that the blade was the same thickness as the chisel I would use to chop the mortise. That’ll make it quicker to chop and less prone to mistakes.
The way I scribed a lot of my lines weren’t too accurate. Next time I’ll do it with more care.
I should’ve sharpen my tools more often, as should anyone. I would’ve made the chopping quicker.
Maybe I should make the handle like 1” shorter. I think I’ll go cut that off now actually.