Thursday, September 6, 2018

Making a tenon saw 1, the spine (a bloody mess)

With the rehab of the Simpson saw out of the way, I felt confident enough to start on the tenon saw that I would make from scratch.
Technically I had already started it while at home, with borrowed tools that we haven't got out here.

The saw plate was supplied by Pedder, and he had not only stamped out the teeth, but also sharpened them for me :-)

I bought a piece of brass plate at a local metal working shop, and it was enough to yield two spines if everything went OK. It could have been thicker, but I had to settle for what they had which was 2 mm (~5/64")
At home I sawed it in half with the table saw. A positive thing was wearing safety glasses and ear protectors. A negative thing was wearing short sleeves.
The blade threw some fairly large and very sharp brass chips at my right arm, so when I was done it looked as though I had been fighting in a thorn bush.
Even my wife was impressed! I am still not sure if she was impressed by my stupidity or my manly looks with a perforated right forearm.

I haven't got a metal bending brake, so I decided to ask our local fork lift dealer if I could use their equipment. Those guys are always incredibly helpful, so I bought a case of beer as a way of saying thanks for the many times they have helped me by letting me borrow a special tool.
I can highly recommend to give them a call if you are even in need of a forklift or some service. It might help if you are in Denmark, as I am a bit uncertain if they do international service as well. But they just might.

So N&V truck had a metal brake that I used for bending the two spines the initial piece of way. That way I had something like a V shape.

I headed into the other part of their shop and aimed for the 25 tons hydraulic press.
My idea was to gradually close the V to a nice spine for the saw. So I tried that with the first one. It was definitely not a success. By doing it gradually (lengthwise) the entire back ended up having a swoop upwards and a not very straight line.
I was glad that I had a second chance. The next piece I managed to find some large steel bars that were so long that I could press the entire piece lengthwise in one operation. The most difficult thing however was to balance a V shape on the side with an 80 Lb steel bar on top, and not getting my fingers squashed in the process.
There was remarkably little cursing and swearing in the process, but somehow it ended up looking really nice.
I decided to take full advantage of the 25 tons of pressure available, so the spine was completely closed.

It had seemed like a great idea at first, but once out here I realized that I wouldn't have a chance of getting the saw plate into the spine unless there was some sort of opening.
Prying the spine open was quickly ruled out. I was simply afraid that I would ruin it. The logical step was to saw an opening all along the 20" of spine.
This can be reasonably fast if you have a thin circular blade and a milling machine. It might even be a pleasurable job that way. grinding down a hacksaw blade to remove any set of the teeth, wrapping it in tape and using 2" of the length as a mini saw sure wasn't fast or pleasurable at all. But I got an opening for the saw plate without messing anything up.

Filing and sanding the spine was uneventful and quite pleasant because it looked better and better for every change in grits.

Getting ready to split the brass plate.

Initial trickle of blood.

Metal bending brake.

Final setup.

Two spines, OK on the left, swooped and crooked on the right.

Re-opening the spine with a hacksaw blade.

First side getting filed.


  1. That press looks pretty awesome! It's good to know people who have machines like that. The spine is looking good. It's going to be another big ass backsaw!

    1. Hi Brian.
      Thanks. I agree that if you can't have the tools yourself - it is a great possibility to be able to borrow the tools.

      I hope this next saw won't disappoint.


  2. Hi Jonas!

    The second spine looks close to perfect!

    (My teeth are completly filed, sold the retoother a few years ago.


    1. Hi Pedder

      Thank you so much for the nice comment.
      I am in awe that you took the time to file the saw plate for me all the way from scratch! I was certain that you had a retoother.

      I think the spine will be OK even if it is not so heavy as the old Simpson spine. It might even be a small advantage, because that one sure feels a bit heavy in the front.

      Have a nice weekend :-)
      Best regards

    2. Hi Jonas,

      I sold the retoother to a friend, who has a better hand fo maschines than i have. But on small teeth like 9 or 10 pi filing ist done fast. And causes less tension in the blade, wich has to curred after stamping.

      Why do you file the spine?

      I really like spines, that are tapers over the length. That makes the toe a bit less heavy and the stearing easier.


    3. Hi Pedder.
      It makes sense that stamping teeth will introduce a bit of tension in the blade. But I have never really thought much about that before.

      I filed the spine on the bottom because it was not flat. One of the sides were a bit longer than the other one in one end of the spine. The spine ended up with a very slight taper of 1 mm from the back to the toe.

      I also filed the sides to remove a few tool marks before sanding it.