Adventures in saw sharpening

These last few months, I have been slowly getting together some tools and rehabbing them. So far, I have four saws. One of them is a nice old rip saw that is about worn out (not much blade left), another is a Disston that might be about 50 years old. I also have an almost new and not-too-rusted Stanley backsaw that has a price tag on it of about US$12. Another saw that I haven't rehabilitated yet is a really old dovetail saw with damaged saw nuts and a handle that is worn out but still usable.

I have sharpened each of these saws once (except the dovetail saw). I filed the Stanley backsaw for a rip cut. It was my first ever try at sharpening a saw. I did this one without a proper saw vise, without proper lighting, and without any jigs or aids.

The blade on the Stanley backsaw was a bit rusted, so I sanded it down and then filed it. I think I set it before filing it or after a first pass at filing. In retrospect, I put way too much set in it. Even after another filing, it would probably still have too much set for my work. It is about 13 teeth per inch and cuts reasonably well now, although it leaves a rough kerf. I did stone one side of the blade after sharpening to make it cut a bit straighter. It could be improved upon considerably, but it is better than it was.

My second was a nice old rip saw with little blade left. The blade was pretty straight with no major kinks. I corrected a few little things with a few hammer blows. It didn't take much and it straightened up nicely. The big problem was that the saw was breasted, but it was not even. Instead of a nice curve, the edge formed a sort of wave. I jointed it until some of the teeth were all but gone (and those are big teeth at about 5-6 tpi). Then I had to reshape the teeth and then file.

I had a saw vise for this one and better lighting. I also wore out a file on this saw. Really, I should have been well into a second file, but I kept using the old one since I wanted to finish and didn't have a second one. It now cuts much faster and also tracks nicely. I still am not happy with the shape of the saw since even though it is breasted, it still has a flat spot at the back. I have pretty long arms and so I use the full length of the saw and the flat part bothers me a bit. On the next filing, I will probably work on it some more. I suspect that I could still make this one cut about 50% faster with some more work. It may take a couple more filings for me to get there though.

My third, the newish Disston, really helped me to understand the difference between a quality saw and a cheap saw. This was a modern saw that was not high quality. It was filed originally for crosscut at about 8 tpi. It was dull, but the teeth were in pretty good shape. Also, it was a bit rusty, but not pitted.

First of all, I spent several hours sanding down the sides of this one to try to get it to something resembling shiny. I started with paper that was too fine and ended up switching back to some pretty rough paper (about 80 grit I think) before working back up through the grits to 320 or 600 or something like that.

You see, this was a cheap saw, and it had a really rough finish from the factory. I am not sure how to describe it, but the surface of the steel blade was almost textured if you looked closely. I didn't get it all out, but I did smooth out a lot of it. I still wouldn't say it has a mirror finish, but it does reflect some light.

After finally getting the surface smoothed out, I thought I was getting somewhere. I was wrong.

Even though the blade was seemingly straight with no noticeable kinks, closer inspection revealed a different story. You see, after the rip saw, I was of the opinion that straightening a saw would generally just involve a few well placed hammer hits and all would be sunshine and flowers again. As I started to apply some judicious hammer blows to this one, it became readily apparent that things were not that simple. Remember, this is a cheap saw. I doubt it had ever been tensioned or straightened. I would guess that the blade came straight out of the steel mill, had some teeth cut into it, a handle bolted on, and a price tag stuck on it.

As I started to try to straighten it, I quickly began to wonder if it was even possible. Whereas the rip saw had only required fairly light blows, this one was requiring heavy blows to do anything. Also, it seemed that the more I worked, the worse it got at first. I finally figured out that I needed to remove any cupping from the middle of the blade and then work on the top and bottom edges to straighten the saw along its length. After several hours of work, I finally got it about as good as I was capable with my newly acquired experience and poor equipment. Instead of an anvil, I used the side of a sledgehammer that I had flattened a bit with a file. For a hammer, I used a common Sears carpenters hammer and a half-sized carpenters hammer I had. I mainly followed my instincts and this forum post to straighten the saw.

Then I set the saw and started to work on the sharpening. This was my first crosscut, so I made a little jig to hold the end of the file at a consistent angle, and it helped tremendously.

I thought I had put too little set in the saw and almost put more in it, but after using it for a while, I think it has plenty. As for the straightness, the saw looks pretty straight and cuts straight. I don't think I got it tensioned properly (I think it is too flexible), but it does reasonably well. I don't plan on touching it until it needs to be sharpened again. I will probably try to put some more tension in it eventually.

All in all, I probably spent 10-14 hours on this saw. I did learn a lot, I could do it a bit faster now, if I had to do it over, say maybe in 8-10 hours or less with the proper equipment. It is, however, very tedious and somewhat boring work even for the most patient among us.

Lessons learned? If you are just getting into saw sharpening, or not satisfied with your results, you should avail yourself of every possible tool and aid. This isn't rocket science, but it is very tedious. Go over to www.toolemera.com and read the old saw sharpening manuals there. Go to www.vintagesaws.com and read their article on filing saws. Read Leonard Lee's The Complete Guide to Sharpening, and so forth. I haven't seen it, but you could also try Tow Law's handsaw sharpening video.

Not only should you be doing some reading and studying, but you should also try to avail yourself of every possible aid. Proper lighting is extremely important. You need the light to come from behind the saw so that it reflects off the tips of the teeth. How else are you going to know if it is sharp if you can't see it? You need a vise or some mechanism to hold the saw properly. Good files, a handle for both ends of the file and so forth.

I still haven't turned out a saw that I didn't think could be improved upon considerably, but so far, they have all been quite usable and greatly improved from their previous condition.

With some study, preparation, and much patience, even the uninitiated can do a decent sharpening job.

Luke Townsley
www.UnpluggedShop.com
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