Amateur saw filer needs practical tips

[Michael Ray Smith]

A few months ago, I described the horrible results produced by my first attempt at filing a handsaw, and I received several good tips that helped me move down the road a bit in improving my technique. Now I'm ready to tackle a few of my acquisitions that need more than just light sharpening -- they're seriously out of joint and the teeth need to be re-shaped, big time. However, I'm not yet ready to even think about changing the TPI or anything else that involves filing below the bottom of the existing gullets.

My first practice attempt at jointing and resharpening wasn't too bad if you didn't look closely, but when I tested it out, the saw nearly jarred itself out of my hand. Well, maybe I'm exaggerating a little, but not much. Looking just a little closer, I could see that the teeth were not of uniform height, i.e., the tips of the teeth weren't in a line. So when I tried to use it, the saw jumped from one long tooth to the next. I've re-read much of the handsaw-sharpening advice on the web on jointing and re-shaping teeth, and in my next attempt I'll pay more attention to the size of the flat on top of the tooth and trying to remove about half of it from each side -- and then stopping!

Does anyone else have any particular advice? Tips that helped you advance past my current neophyte stage?

Thanks!

[Chris Griggs]

Make sure you have a good lighting - I don't in my shop and it makes filing that much harder. I sometimes grab a table lamp from upstairs.

Use marks and guide blocks to as much of your advantage as possible. I always at least mark the tops of the teeth with colored marker to help me see when the flats are gone. When I'm setting teeth and/or filing a crosscut saw, I will also mark the side of every other tooth (the ones pointing away from me) to avoid either setting a tooth the wrong way or filing fleam in the wrong direction. If I don't do this I almost always screw up and file a tooth the wrong way.

Always use a rake guide block, and really work to keep you rake angle consistent. A little variation doesn't actually matter, but if you get to far off or consistently of in one direction you are likely to end up with varied size teeth.

File from one side and one side only when ever possible. I always shape from one side, always file rip from one side and often file x cuts from one side (though some will disagree with that practice).

Most important...file deliberately, bias your lateral pressure as need to file the flats evenly. There's a good chance you'll have a natural tendency to file a little harder to one side of the other, so don't assume that you are filing evenly on both teeth just because it feels like you are. You need to watch the flats, throughout the process, and adjust accordingly throughout, especially until you develop a little muscle memory.

For the saw you are talking about I would give it a nice heavy jointing and more or less reshape from scratch. Good luck... you'll get there with a bit of practice.

[Chris Griggs]

Another thing. One of my nice old disston rippers always cut the way you're describing - it would jar up about halfway through the stroke. I refiled it a couple times being very careful to make sure the teeth were even, but no matter what I did I couldn't get it to behave well. There were no kinks in the blade. Finally, I held a wood straight edge up to the tooth line and could clearly see that the tooth line was slightly concave throughout its length. It was like the center had been filed more heavily over the years. Sure enough, the point where the saw was jamming was right about where the concavity turned back up hill - deeper heel was clearly catching. I still haven't fixed it completely - even though the concavity appeared subtle there was/is actually a good deal of metal for me to remove on the toe and heel to get it straight or slightly convex (convexity is fine).

[Jim Koepke]

Patience and practice is what will eventually help you work your way to fine saw filing.

If you need a fleam guide, here is my solution:

http://www.sawmillcreek.org/showthread.php?180440-Saw-Fleam-Bevel-Gauge

Since this post a second kerf has been added to help with changing position on the saw when filing from one side or the other. Marking the fleam angle on a piece of wood to reset the gauge when changing sides is helpful.

When a saw doesn't cut well, a straight edge can help find the offending teeth. Also a small block of wood to pull along the teeth backwards can help to find tall teeth. Sometimes a few short teeth will cause the same problem.

My tendency is to file from both sides of the saw. Even on a rip saw. My reasoning for this is the burrs all end up on one side when the filing is from one side. This can cause the saw to pull to one side. Stoning can take care of this. For me the short rest in the middle of filing while turning the saw around is refreshing.

Sometimes it is necessary to "finesse" the file toward the face of one tooth or the back of another to "attack the flat."

Another consideration is that old saws may not be of the same hardness over the full length of the plate. This can cause a difference in tooth geometry even though the filing is done with the same pressure over the full length.

My filing is definitely not professional grade. Though each time one of my saws is filed a new bit of understanding comes my way.

Have fun and let us know how things start coming together.

jtk

[Isaac Smith]

Lighting is very important. I file with a single point light source, specifically an LED light with a flexible neck. No other lights, as they are distracting and impede visibility. I position the light about six inches away from the teeth, directly opposite of where my eyes are. If you think of the tips of the jointed teeth as a mirror, I like the light to bounce off of them and directly into my eyes. This makes it easier to see the teeth and their reflections. You will need to reposition the light every couple of inches or so.

I use Dykem before every pass I take with a file. If you are filing the teeth on a saw that has not been sharpened recently, there will be a large contrast between the patinated surface and the freshly filed surfaces. This makes it easy to see where you have filed. However, on the next pass, it is extremely difficult to see what you have just removed. Using Dykem (or a marker, or soot, or what have you) to completely color the entire tooth (including the gullet) makes it very easy to see what you have just filed.

Even if you have very good eyesight, take a look at your teeth under magnification. I have excellent eyesight, and I still routinely check each tooth I file with a 10x loupe. It can be very enlightening. Even when your eyes tell you the teeth are good, magnification will often reveal a small land on the tip of a tooth (they really stand out because of the Dykem). If the intersection of the front and back of the tooth is not a perfectly straight line, the tooth is not as sharp as it can be.

Given your experience of a jarring cut, you now know the necessity of jointing. After jointing and marking the teeth, concentrate on removing the flat, or land, on the top of each tooth. File only enough to remove this flat, and no more. You can also work on keeping the teeth a consistent size and depth, but in my opinion, it is far more important to have all of the tips in a straight line. Evenly sized teeth look nice, but will not greatly improve the cut. As a matter of fact, many older saws were sold with graduated teeth, in which every tooth is larger than the preceding.

Those are just a few quick thoughts that may supplement what is out there on the web.

Isaac

[Paul Saffold]

I agree with most of the info you've been given, except I file from handle to toe, turn the saw around and repeat on the other side. I have a pair of magnifiers that I clip-on to my prescription glasses. I use layout fluid too. I was amazed what a difference there was even on my first sharpening attempt as bad as it was. Keep at it and you should see progress.
Paul