Tool restoration: Disston back saw

Today I'm restoring a Disston back saw.  It's not an old model but the method is the same.  I should be able to do a good user's saw with it.  We will look at sharpening, rust/paint on the saw blade and how to restore the handle.

This saw has a 17" long plate and 10 TPI.  I will sharpen it as a crosscut saw.

The initial condition is typical.  The teeth are not straight, they form an arc.  I will need to joint them.  The saw plate is straight and there is hardly any rust.  The handle is in good condition but has lots of sharp edges and is not comfortable in my hand.








The saw plate has some sort of lacquer on it and it makes the sanding difficult.  The result is so,so.





The teeth need to be flatten.  You can see below that the teeth are not on a straight line.



I use what is called a "Morin gauge" to hold a flat file.  I first file at each ends because they are the high points.  I know that I'm completed when I can see a flat - created with the file - on every teeth.  All the teeth are now at the same height.



Using a triangular file I begin by reducing the larger flats at both ends of the saw plate.  My goal is to reduce all of them to the same size.

To help me I use a Veritas file holder and I set it at 12 degree of rake and 20° of fleam.

Because the flats are very large at each ends, I rotate the saw in the vice, filing from both sides.  This will help to keep each tooth the same size.  I now have equal size flats and a normal sharpening can be done.

My goal now is to remove completely all those small flats very carefully.  I stop filing immediately when the flat disappear.  Most likely I will need to set the teeth but I will not do that until I can make a test cut and see if it's really required.

I now begin to work on the handle which have 95% of it's original varnish.  I remove it because I want to round all those sharp and uncomfortable edges.

With the side of a chisel or a card scraper I remove the varnish.

I've rounded those edges with a rasp, sandpaper and a card scraper.  It took 10 minutes and that handle is now comfortable in my hand.

Two coats of shellac and 0000 steel wool.  I then complete with bee wax.

I reassemble the saw and it's the moment of truth.  Is it cutting properly - easily and straight?

No, not really.  The teeth needs to be set.  When I sharpen a saw this is the part that where I need more practice.  It's a bit tricky to do this properly and it's very easy to bend the teeth too much.  Not enough set and the saw will bind in the cut and too much will mean a larger cut - more effort for nothing - and a saw that will be difficult to cut straight with.

Tool for saw setting.

Too much set can be fix by stoning lightly the teeth.  One light stoning on each side and I go for a test cut.  Repeat as many times as required.

The goal is to have a minimal set.  This will help you for sawing to the line.

 This is the final result.

It's not a fancy expensive saw but it's working properly.  That was the goal.

Normand