What if you could sharpen a crosscut saw in a special way, then for several future tune up sharpenings it would only take a few minutes to keep the saw cutting well?

I’ll call it inverse filing for three reasons; one, it is completely reversed from traditional filing instructions; two, only the back side if the cutter tooth is filed for tune up sharpening and three, the cutter is filed toward the cutting edge rather then the normal filing away from the cutting edge.

The basic idea is to file a saw so that the cutter teeth set is a little more then ideal and the rakers are a little shorter then ideal with the ideal that the tune up filings will bring the settings into the “ideal” range and maybe a little beyond. At the same time the settings at any time are still within an acceptable range for a good cutting saw.

Start with a saw with the whole cutter teeth set as needed, that is the tooth is bent out near the body of the saw and not just the tip of the tooth. A well tapered saw would work fine with 0.008” of set and the rakers at 0.008” lower then the cutters. So when the saw is set up (full joint and sharpening) the set is set at 0.014” and the rakers are set at 0.014”. The saw should cut fine with these settings. Then when the saw gets dull, only the back sides of the cutters are filed to remove any dull surface on the cutter tips/edges. On the saw I’ve used this method I measured that about 0.0005” needs to be removed to sharpen up the cutters. At this rate the saw could be tuned up about twelve times before a full sharpening was needed.

I’ve did this on my broken, welded, patched falling saw and other then one hitch it has worked fine. The problem I had was after three or four cords of firewood cutting the saw would start to bind up in the cut after 5 to 10 inches into the cut. It acted like there was not enough set, but there plenty of set when I checked it. It did cut fine up to that point. Then I figured out that most files are twisted and that when I flat filed the cutters I was not filing the cutters in line with the saw. This caused problems, especially when the saw started to get dull. The last time I used the saw, last fall; it would only cut about 6” and start to bind. So recently I spent about 15 minutes to tune up the saw, making sure to use a flat file. Then just to test the saw I went out and cut about half a cord of firewood today. It cut well with no noticeable dulling or binding. If my past experience holds, it should be good for another four plus cords of cutting before I will need to tune it up again.

On the saw I have filed like this the rakers have not needed any attention. They are quite hard and hold an edge well. They may need a little touch up at some time before fill filing is required.

With the setting on this saw now at about 0.013” of set and rakers about the same I figure that saw will be good for probably six to eight tune ups before it needs a full sharpening. That works out to something like 24 to 30 cords of firewood with just a short time in the filing shack. It is going to take several years to fully run the course of confirming my idea.

There seems to be several advantages when using inverse filing. Less wear of cutter length, IE the saw will last longer. You can get more tune ups then the normal filing method before full jointing and sharpening are required. It is easier to file, no angles to worry about. Much faster to tune up a dull saw just a few strokes per tooth, less then 15 minutes per saw. No burr or wire edge because the filing is into cutting edge. Filing the back side cleans up any pitted surface on the back side of the cutters.

I don’t think I’d recommend that everyone run out and convert there saws to this method but it may be interesting to consider or try on a limited trial basis. It is a major deviation from how we were taught to sharpen a saw.

Comments, questions and suggestions are always welco