Sunday, March 13, 2016

Backsaw with copper back 3, the saw plate

When I attended the ATC class at Dictum five years ago, Chris Schwarz told me that it was possible to make a backsaw using the steel from a plaster scraper, if a person just wanted to try making his own saw, and do it in a cheap way.
I found a shop in the port where we are at now, that has cheap tools. So I walked there the other day and bought myself two 10" scrapers at around 10$ a piece. 

Normally I dislike destroying usable tools, but I decided that this destruction would serve a higher purpose.

I didn't want to accidentally bend the steel plate, so I decided not to bash the handle with a hammer to loosen it. 

After a bit of experimentation, I decided that the easiest way to remove the future saw plate from the scraper was to first split the upper part of the scraper where the two halves met. I think the two handle parts were cast separately and pressed together later. There was a clear joint that was easily split using  hobby knife.
With the plate mounted in the vice, I used a heat gun to soften the plastic on both sides.
As soon as the plastic softened, I pulled the two halves from each other. That made the upper part of the plate accessible.
A bit more heating and I cut through all the plastic that was in the holes of the plate.

I didn't time myself, but I think the process of removing the plate could be done in 10 minutes, if you don't try to experiment with other removal methods first.

The plate itself is 0.5 mm thick (0.02"), and on the plastic handle it said "Made in Sweden", so I guess that the steel is also Swedish. There is a very slight cupping along the length of the steel suggesting that it came from a roll. But it is easily within the capabilities of the back to keep it straight.

I used a tool bit from the lathe to scribe a line on the plate, so I could cut off the holes in the top. A small file or a permanent marker could have done the same. A pair of metal shears easily cut the thin plate.

The dovetail saw I have at home has got 20 TPI, but I didn't think I could manage to file that fine a set on my first attempt. So I settled for something a bit easier: 18 TPI.

I printed out a diagram, but it was 7% too small, so instead I wanted to use a trick advocated by Pedder from Two Lawyers Toolworks. The trick is that if you are going to make very fine teeth, you can use the blade from a hacksaw with the same toothing as a guide.

After about a third of the saw plate, I decided that it didn't work very well for me. Probably due to a crappy work station. I couldn't stand in a decent way with the file, and the whole idea of a narrow saw vice was somewhat destroyed by the way I had fixed the plate.
I took a quick decision and removed the hacksaw blade - and made the rest of the teeth freehand.
In hindsight I should probably have read up on how successful people file a set of teeth, but I never bothered.
My approach was to file every other tooth, and then reverse the plate and file the remaining teeth. It doesn't look too pretty, but the saw works which is the main thing. I'm sure the correct tools will help quite a bit, but it can be done without them as well.
My file was a triangular needle file, without a handle, so I ended up wrapping some tape on it to protect my palm a bit.
At first I just made an indication of where each tooth should go, then followed up with a second stroke to form it.

Raw material for a backsaw.

Splitting the handle.

Heat and a hobby knife gets the plate out.

This is what it looks like.

Nice looking Swedish spring steel (presumably). 

Start of filing the teeth.

These were filed freehand.

Half the teeth done. The other half started.


  1. When I made a backsaw a long while back, filing the teeth was definitely the worst part. I may try it again some day with the TGIAG link you sent, since the handle making part is pretty fun.

    1. Hi Jeremy.

      I agree that making the handle is quite fun. If you look at Two lawyers toolworks, they take the handle making to completely different levels. Their saws look absolutely stunning.
      I think I'll have to try making a new handle at home using some decent wood instead of plywood. Or perhaps I will bring some wood with me on board next time.

  2. What a great project to undertake in your floating workshop! You've convinced me to add a backsaw to my to-do list.

    It sounds like you're having issues printing pdfs formatted for US letter-sized paper on A4. Usually you can go in to the printer settings and tell the printer to not compress/modify the print size and make it work.

    If you're having trouble printing bitmaps, jpegs or other image files, try downloading GIMP. This is powerful image editing freeware, and will allow you to scale or change print resolution, and there's even a set of dividers (calipers) to help you with measuring on the drawing itself.

    1. Hi Hans

      Thanks for the comment.
      Making a backsaw is actually easier than I thought. But if I didn't have access to a hydraulic press, (and I wasn't so cheap), I would probably order a set from TGiaG or a similar place. But I like making stuff the hard way, that way I can easier come up with a n excuse if something goes wrong too :-)

      I tried all the setting s I could find on the printer, but I really couldn't make it work. I even tried to copy the image to a jpeg file, then enlarged it and printed. But that wasn't a success either.
      We're not allowed to download programs to the ship's computers, so the GIMP route is also kind of closed.

      I think that the "problem" is that computers and computer programs get the same attention from me as the Danish handball team i.e zero :-)

      But thanks for the suggestions.


  3. I once saw an article in a woodworking magazine showing a small jig which could be used to file the teeth into a new saw plate. I have to imagine that it would take several files to complete one blade, as it must be pretty hard on a file to create a tooth from scratch.
    I think it was Tom Calisto who had refurbished a saw filing machine, but I've yet to see one of those on the market.
    Either way, I think your saw looks awesome!

    1. Hi Bill

      Thanks for the nice comment.
      Actually the steel isn't terribly hard. I was amazed that I could even drill it without too much trouble. I have to admit that I used a brand new drill, but still it went way better than I had anticipated.
      At, the author suggests that you only use one side of a file for one saw plate, because files are cheap and working with dull files won't get you anywhere. But I guess he is thinking about somewhat larger saws. I didn't have any problems. But the teeth I filed are really small.
      A saw filing machine sounds like a wonderful and unnecessary thing to have. I am a sucker for old machines, so if I ever stumbled upon a cheap one I would probably try to buy it.

      I think Foley Belsaw made some machines that could stamp the teeth on saw plates. Having one of those would really make it a lot easier. I have to admit that accurately filing 20 TPI is not easy for me. But on the other hand. I have no intentions of taking up saw making as a profession, so being a bit slow doesn't matter.


  4. I like your methods, just get busy trying something, if it works, great, if not, try something else until it does work. That is my way of doing things as well. Eventually you become skilful because you have spent a long time in the University of Experience.

    1. Hi Johann

      Thanks for the nice comment.
      I sometime think about making a "real" project from proper parts, but in a way I am afraid that it would remove some of the fun.