Jointing and Setting
After a few of the simple sharpenings (say 3 or 4) the teeth will probably have different heights (fig.1), the toothline may have lost it’s straightness (fig.2) and the amount of set will have decreased so the saw may have started to bind in the cut.
Overall the saw will no longer perform as well and the steps to bring everything back to alignment are as follows:
1. The first thing to do is jointing the teeth to the same height with a mill saw file (fig 3). This creates flat tops on the teeth. Have a look at the teeth before jointing to see where the teeth need to be lowered. Look for high spots/curves at the toe and heel (fig.2) and individual teeth that are too low (fig.1) . Work towards a straight toothline where all the teeth have a flat top (fig.4).
2. After jointing the teeth need shaping by filing towards consistent tooth size and rake and fleam angles. File the gullets deeper until the flat tops have almost disappeared. At each gullet look at the flat bigger flat and while making a pass with the file, press the file slightly towards the bigger flat while keeping the angles of the file the same (fig 5). This should equal out the the sizes of the teeth. This takes time to master but if you lower a teeth accidentally, just joint again until it has a small flat top again and continue the process.
3. If the teeth need setting, I like to set them after shaping but before the final sharpening passes with the file. The advantage is you file away any marks or imperfections that a saw set can leave on the teeth. (You can also set the teeth at after sharpening if you prefer this)
I prefer the older Eclipse 77 saw sets, but a Morril’s saw set is also very good if you can find one. The Eclipse saw set can be improved to make very precise set on very small teeth, by refining or sharpening the corner of the anvil. Newer Eclipse saw sets have bigger hammers and rounder anvils, these can also be modified by narrowing the hammer and turning the anvil over and honing some new custom bevels on the anvil. (read more here about improving the Eclipse saw set)
Aim for just enough set for the wood you are intending to cut. Start out with a little and test it out. Even before the final sharpening you can cut with the saw and get a feel if its enough. Too little and it will bind, too much and the saw will wander in the cut. You may prefer to have some more set so you can steer the saw a bit, or you may prefer to have less for best tracking. Once you have found a good set you can measure the kerf width (fig.6) for repeatability with calipers by measuring over a few teeth at the same time.
4. Stoning the sides of the teeth (fig.7) helps to even out the set and makes the saw smoother in the cut. One light pass with a fine stone on each side of the toothline, preferably with a fine diamond stone (because it stays flat). Use masking tape on the stone so only the side of the teeth are stoned, while the taped area rides smoothly over the side of the saw plate (fig.8).
5. The last step is the final sharpening to create the sharp edge. If you do this very gently on the last needed stroke, you will get a smooth and sharp edge, plus teeth even in height. Work your way from the heel end to the toe end of the saw. After each stroke with the file, look how much of the flats is left.
Keep in mind that you sharpen one tooth from filing in both adjacent gullets, and that you sharpen two teeth at once with the file in one gullet. So when you have removed half of the flat of the tooth in front of you, move to the next gullet.
Once only a few teeth have flats you do the same as in fig. 5 and put light pressure towards the tooth with the flat until all has disappeared. Now the saw should be sharp and you can check this by looking over the saw with a light behind it to check for any remaining reflections and by feeling with your fingers over the teeth. They should feel sticky and pull on your skin.