Changing the Rake Angle on a Back Saw

[Richard Line]

I have a Davis back saw (private brand of Disston) that I like the feel. My only complaint is that it seems to cut slow; yes it is sharp. The saw is 12 in. long, 13 ppi, filed ripe with a 15 deg. rake angle (measured using my Veritas file holder).

I want to reduce the rake angle to 10 deg., at least as a 1st step. Is this changing the rake angle seemly sharpening it with the new rake angle. Will I need to take multiple passes. Am I completely missing something here?

Thanks for you help.

[Jim Koepke]

15º is a very relaxed rake for a rip saw. No wonder it is a bit slow. You may find 10º also a bit slow once you get used to it.

Vintage Saws.com suggest 8º for beginner's rip saws.

One of my most recent saw sharpening endeavors was to file a small back saw at 13 ppi with 5º rake and fleam. It is very fast and aggressive. Works well rip or crosscut.

The amount of work it takes to change the angle depends on the hardness of the saw. Try to work each file stroke with the same amount of effort. Keep a close watch on the teeth and you will quickly see how much work is needed.

It will likely only take two or three passes to reshape each tooth.

Let us know how it goes.

jtk

[Chris Griggs]

That's the rake angle you'd generally put in a xcut saw. Are you sure its filed rip and doesn't have any substantial amount of fleam in it?

Anyway, changing the rake angle isn't hard. You just need to joint the saw down further than you otherwise would.

Because it is rip you can file it all from one side without filing every other tooth. Just go down the line tooth by tooth at the new rake angle taking a few passes on each tooth trying to keep the flats even. You may have to go down the tooth line a couple times until the flats are gone.

The one issue you may run into is if it already has minimal set jointing it down to much may mean that you need to add a bit of set back in. So start with the idea that less is more. You don't need to joint the teeth WAY down. Just enough so that when the flats are filed away you are hitting the front of one tooth and the back of the other all the way to the tip with file. You'll see what I mean when you do it, but the first few file stroked you'll only be hitting the back of each tooth at the tip of the tooth line because you are turning the angle towards the toe. If the first filing doesn't get there you can always joint a little more and continue filing, but unless you are Dr. Manhattan it is difficult to add steel back on.