Wednesday, May 22, 2019

Large Try Square

I need a large try square. I really like the look of the try square Chris Schwarz built based on the try squares from Benjamin Seaton. He wrote an article for Popular Woodworking that you can buy with how he did it, but I thought I could figure it out and put my own touches on it.
Here's the finished square.
I realized I needed a bigger square when I went to cut a panel down to size that is about 16" x 12". My little six inch combination square just wasn't accurate enough.
This is the only square I have here.
I started to think of Jonas, and the fact that he doesn't think you should build a tool in order to finish a project. (He later told me he probably would have just used a piece of paper as a square.)

By and large I agree with him, but I figured if I made an accurate tool that looked nice, I would probably be able to keep it and use it for years to come.

I recently pulled an awful lot of awesome wood out of the Golden Dumpster. More than 100 linear meters of  flat, 3/8" sapelle boards that are 3 1/2" wide and about six and a half feet long. Perfect for the blade of this square. The only problem being that one side is covered in white paint. I used paint stripper and then a card scraper to clean up the wood, and wound up with a blade about 5/16" thick, 3 1/4" wide and 17" long. For some reason this stuff is extremely difficult to plane, so I just left it at that, skipping the original tapered blade detail from Benjamin Seaton's squares.

The stock I chose was from an abandoned project of a plane build. Maybe I'll get back to that build someday. I have plenty more wood. This blank was already squared up and measured 1 1/4" x 2 1/4" x 11" or so. The only defect being that I had used a marking knife to lay out the angles for the plane I was working on before. I decided to leave those marks on the plane to remind me of where this wood came from. Oh, by the way, before it was going to be a plane, it was a stair rail that I found in the Golden Dumpster last year.

I didn't use any specialty tools for this build, except perhaps my new Veritas skew rabbet block plane that I got from Goerge. That plane wasn't necessary. One could use any old plane for the chamfers, but it's new, I have it, and it worked great.

I don't have a 5/16" mortise chisel here, so I decided to hog the waste out with an 8mm drill bit in my eggbeater drill. I marked where I was going to drill on each side, drilled three holes about half way, flipped the board over and drilled the rest of the way.
Starting the mortise.
Once that's done, I just went at the rest of the waste with a 3/4" bench chisel until I was all the way through.
I started in the middle, and worked my way out.
Pretty soon I had a decent looking Domino hole.
Still needs some tweaking.
I used the 3/4" chisel and a 1/4" chisel to clean up the shoulders.

I used my Dick saw (Ryoba) to cut the bridle joint on the top. This was way easier than I imagined it would be. Careful layout defined where to cut, then I just dropped the saw down to my mark. To get the waste out, I just chopped straight down to sever the fibers, then went in from the end to split out the waste, little by little.
Nibbling away the bridle joint.
Next I routed out a small bit with a chisel to connect the two joints. This is not critical, but it should make for a cleaner look. The cut away part on the blade will sink below the level of the stock so there is no chance to see a gap.
This part doesn't have to be deep. I think this is somewhere between 1/8" and 1/4"
Now comes the fiddly part. I think a sloppy joint here would be easier, and it would hold just fine, but I wanted the visible part on the back to look really clean. It basically took me a whole day of fettling, but I finally got the blade to slide in without too much force.
Halfway there.
Strangely enough, even when I got the blade to seat all the way, I had to continue fiddling with it. Every little hang up in this mortise is an opportunity for the joint to through the blade out of square.
Perfect fit.
One shouldn't use the inside of a wooden square because it is difficult to true up. I, however, wanted the inside to be as close to square as I could get it on the glue up. All that time fettling the joint paid off, as once there were no tight spots, the inside corner was dead-nuts on 90 degrees. And, it stayed put during the glue up.

Before I glued it up, I cleaned up all the surfaces, added some nice chamfers to the non-precision areas, and put a roundover that I laid out with a five Euro cent coin. Once I was happy, I glued it up with hide glue and added a c-clamp to the bridle joint.

After it set, I removed the clamp, cleaned up the squeeze out, planed the back flat and added a couple of cosmetic wedges to make the joints look better.

Linseed oil and soft wax was applied, and I was almost done.
I'm pretty proud of these joints.
All that is left is to tune the square. I mentioned that the inside corner wound up perfectly, but I think I'll not rely on that angle except for double checking and rough layout. The outside edge can be tuned to a very high tolerance.

It's easy.
Checking for square.
Just draw a line with the square, flip the square over and check how close the square is to the line. This square wound up being a little off. I suspect the joint caused the wood to move a little, throwing that outer edge out of square.

No biggie, a few swipes with a plane and check it again. I soon had an edge that is very, very close to perfect.

I look forward to using this try square. It makes me happy to look at it. It should last me many years. If it goes out of square, it is a simple thing to tune it again like I did this first time.

Here's some detail shots:
That little rabbet made this joint look very tight.

I wanted to practice this round over for a plane build.
What a fun little square to make. Let me know if you make one, I'd love to see it.

Next up: a famous celebrity will make a guest post about squares. You'll love it!


  1. That came out great. I still cringe every time I read "dick saw."

    1. Thanks, Steve! Haha, we must all find our entertainment where we can get it.


  2. Great project. Often the rabbit trails we take along the way to completing the project become as interesting as the "real" thing.

    1. One day I'll be as accomplished of a rabbit hunter as you! :D

  3. I am a firm beleiver in making the tools you need and this wil fill its purpose in many years to come. And looks good too

    1. Thanks, Ty! It's a bit chunky. Perhaps someday I'll make another.


  4. What, no fancy ogee curve at the end of the blade? That round-over of the chamfer looks so damned good. Nicely done!

    1. Hey, Matt! Thanks for the nice comment!

      No, Benjamin Seaton didn't do a fancy ogee curve, so I decided not to, either.

      For the roundover, I laid it out with a coin, then did the chamfers in the usual way with a plane. To get the rounded chamfer, I just used a paring chisel to even everything out the best I could by eye, then I cleaned it up with some 320 sandpaper.

      The idea was to practice that, since I hadn't done it before and I want to use that on a plane build I've been working on.