Reshaping/Sharpening Saw Teeth

[ChrisG]

Hey Folks,

This is my first time posting to this forum. I'm somewhat active at another "neanderthal haven" (the one up the creek near the sawmill), but I decided to stop over here for a change.

Anyway, I decided to try my hand at sharpening a couple handsaws this week. I started by doing a light sharpening on a 7ppi rip, which, to my surprise turned out very well. So I thought to myself... "this whole saw sharpening thing isn't all that hard"

The next night I decided to try my hand a 26" 8ppi crosscut saw. I made some guide blocks for both fleam (20 degrees) and rake (15 degrees - relaxed direction). I gave the saw a light jointing, and set about filing.... this did not go was well as hoped. As I filed I began to realize that I couldn't get the flats to disappear evenly from tooth to tooth. The result - a saw that barley cuts (by the way before I messed with it was cutting ok, just a bit rough).

I've chalked this issue up to two things. 1. I think the rake and fleam I put in must have been too different from the previous filing and 2. I'm thinking the saw teeth may not have been properly shaped to begin with.

So my guess is that I now have to do a heavier jointing and reshape the teeth??? I've watched Bob R's saw filing podcast, LNs youtbe videos on the topic, and read everything I can find online about saw filing, but have a few questions.

First, when reshaping teeth, what do I need to be paying attention/looking for to know I'm doing it properly? Am I mainly trying to even out the depth of the gullets and filing a consistent rake? How do you tell when the gullets are even.... do you mark a line... or do you just eyeball it? For the shaping portion does one not worry about the tips of the teeth since they get rejointed after being set anyway?

Also, when shaping a crosscut do you include the fleam during the shaping process or do you wait until the final filing to put the fleam in? And finally, when doing the final filing on a crosscut how do I know when I've filed enough on the first side? What I mean by that is, when filing a rip the flats disappear evenly because your filing straight across, so it's pretty easy to tell when they are half filed away. But when filing a crosscut the flats seem to disappear at an angle, since your filing at an angle. So is their something additional I need to pay attention to on a crosscut saw when the determining the correct number of file strokes to do on on the first side? Hope that last question makes sense.

Any input or advice would be much appreciated (yes, I know... I need more practice). THANKS!

[Bob Rozaieski]

Chris,

As you have found, it's really easy to sharpen a saw with properly shaped teeth. This is one of the reasons I completely disagree with the recommendation to learn saw sharpening on old beater saws. These old saws rarely have well shaped teeth, and therefore typically require significant reshaping before sharpening. The reshaping is the hard part, especially if the teeth are really bad. That's why I always recommend that first time filers either practice on their shiny new Wenzloffs/LNs/etc., or get a brand new cheap saw from HD/Lowes to practice on. These new saws are going to have properly shaped teeth already. Only after one is comfortable with sharpening properly shaped teeth should one attempt reshaping an old beater. That's my opinion anyway.

As for your conundrum, what I usually do is hold off on filing fleam until the end if the teeth need a major reshaping. Joint the saw down so every tooth has a flat on it. Then file straight across as if you are filing a rip saw, at the rake angle you want in the final tooth (15 degrees in your case).

You want to remove the flats evenly. If one tooth has a much bigger flat than its adjacent teeth, then the adjacent teeth are too small and the tooth with the big flat is too big. So you will need to "move" the adjacent teeth toward the bigger tooth. This may require several jointings to do, so you have to deide of you want to do it all at once, or gradually as you continue to sharpen the saw. I usually just do it gradually rather than waste a lot of steel by doing a lot of jointing. To "move" a tooth, you direct more pressure against the side of the tooth that needs to be moved. Take it easy doing this as it is very easy to go too far and make other teeth too big by moving the tooth too far. It's a delicate process.

As you are filing, don't focus on the gullet depth. This really doesn't matter. You can have perfectly even gullets but still have different sized teeth. When this happens you will have some teeth that stick up above the rest, and that is a bad thing. Instead, focus on keeping the tops of the teeth even, and ignore the gullets. You want the tips of the teeth in the final sharpened saw to all be at the same level. This ensures that all the teeth, regardless of their size, are engaged in the cut, and provides for the smoothest and most effecient cut. If your teeth are not all exactly the same size, the gullets will not be even, but the tips will all be, and that's what is important.

Finally, you are ready to add the fleam. If you need to set the teeth, set them now before you joint again. After the teeth are set (or if the saw had a lot of set to begin with you can skip setting), then joint again and add your fleam, holding the same rake angle. This gives you another opportunity to "move" the last few "too big" teeth as well. Go slow only filing 2-3 strokes on every other tooth. Then flip the saw and file the fleam on the teeth you skipped, again, only 2-3 strokes.

At this point, you will probably still have small flats on top of each tooth. That's OK. You want to add fleam evenly, so it's best to alternate sides and only file a couple of strokes on each tooth at a time so that the flats are removed evenly from both sides of the tooth.

Now, with very small flats remaining, I will flip the saw again (remember to flip your rake guide each time you flip the saw around; DAMHIKT), and go back over the teeth, this time filing only 1-2 strokes on every other tooth. Teeth with larger flats get 2 strokes, smaller flats get 1, and really small flats may not get any depending upon which side of the tooth needs the additional stroke. Once I work my way down the plate, I'll flip the saw (and the rake guide) again and do the same thing, 1-2 strokes, from the opposite direction.

Now your teeth should all be filed to a sharp point at the appropriate rake and fleam. If you still have flats on some teeth, flip the saw two more times, addressing only the teeth with the remaining flats this time. Finally, side dress the teeth with one pass of a hard, fine honing stone on each side of the plate, and test your saw out. If it drifts to one side, dress that side with an additional pass of the stone (heel to toe).

Reshaping teeth that are in really bad shape is a bit of a chore, but once you've done it several times, you get the hang of "moving" the teeth and your filing gets more even. It's time consuming to do it the way I do, but for me it's just best to take it slow, in stages so that I'm only fixing one problem at a time. I just find it easier that way rather than trying to do everything all at once. I can usually do a saw in really bad shape in about 1-1/2 hours. But after it's done, it only takes a few minutes for the touch-up sharpening when the saw gets dull again.

Hope that helps .

[ChrisG]

Thanks Bob! That helps a lot. I was hoping you would chime in. You answered my questions very well.

Both saws I was working on had actually previously been worked on by a friend of mine who had more saw filing experience then me, so I assumed a light filing would be all it needed. This was the case with the rip I filed, but not with the crosscut. I think the reason I ran into trouble was the rake and fleam angle I filed in may have been significantly different than what my friend had filed in, and therefore, I inadvertently found myself having to doing quite a bit of reshaping. Additionally, I think the reason I was having trouble getting the flats to disappear was because I had jointed the teeth down more than was needed. Also, I was taking a lot of strokes per side (10-15), instead of flipping the saw back and forth several times as you suggest.

I actually went back last night (before reading your post) and gave another shot at filing the saw. I realized one of the reasons I was having trouble was because I was not keeping my fleam angle consistent through the file stroke and I was applying too much pressure with the hand (left) that was guiding the front of the file. The result, the teeth set in one direction were getting filed more aggressively then the teeth set in the other, so I was over filing every other tooth. By focusing on a more consistent stroke and taking the pressure off the front of the file, I was able to get to get the saw filed more evenly.

The crosscut saw is now cutting decently again, but I will probably go back a third time, do a light rejointing and follow the advice you just gave.

Thanks again Bob!

[ChrisG]

One more thing Bob (or anyone else). What's you're opinion on sloped gullets? (I've been reading too much about Mark Harrells sharpening technique) Do they make a difference? And how much complexity do they add to the sharpening process? Basically.... are they worth it? I read the Norse Woodsmiths write-up about them but would be curious to here another opinion.

[Bob Rozaieski]

I don't typically file sloped gullets on my crosscut saws, and never on my rip saws. They're not a lot harder to do, but it's just another angle you have to worry about. I really don't think they add a lot, but that's just my opinion. You really need to try it out for yourslef to see if it's something you like or not. Fortunately, when you can file your own saws, it's easy to try things like that . I've filed a few crosscut saws with sloped gullets, and I really didn't notice any difference in cut between my typical crosscut filing (15 degrees rake, 25 degrees fleam) and one with sloped gullets.

One important thing to keep in mind: if you are filing a rip saw, adding sloped gullets essentially turns that rip saw into a low fleam angle crosscut saw, because the process of filing the slope adds a bevel to the teeth. I don't like the way rip saws with sloped gullets cut, so for that reason alone, I never file rip saws with sloped gullets. YMMV.

[ChrisG]

Thanks Bob, again.... You've been quite helpful. I think I'll hold off on sloped gullets until I get better at basic shaping and filing. Definitely, something I'll want to try eventually though.