The ability to sharpen an edge is of utmost importance in woodwork. Without it, the woodworker is destined to hours of frustration, hard work, and ultimately a poor result; luckily, there are many techniques for sharpening that are easy to learn, require no expensive machinery, and with practice will produce exceptionally sharp edges. The key here, however, is practice: you can not learn to sharpen an edge properly by reading a book or even being shown how to do it. These will help, and are even necessary to begin, but it is relentless repetition—many hours spent at the bench, improving at an almost imperceptible pace—that will ensure that you can sharpen tools properly. Thankfully, this is 'all' it will take!
When we say that expensive machinery is unnecessary, we do not mean to imply that a good-quality grinder (for shaping chisels, plane blades, etc.), or specialised honing system, would not be a valuable addition to the workshop. It is however quite possible to produce the same (or better) results with lower-cost tools that are much more convenient for the small workshop, and easier to obtain for the amateur woodworker.
To sharpen all of the standard, straight-edged tools (and saws are included in this category, because their actual cutting edges are straight), one needs a surprisingly small number of tools and materials. These are as follows, and their purchase, preparation, use, and storage will be elaborated upon below.
- files, flat and triangular, of assorted sizes and coarseness;
- saw set;
- Plane blades, chisels, etc.:
- three medium-density water stones;
- a higher-density final honing stone;
- a range of small triangular angle gauges (made of plastic, wood, or something else non-corrosive);
Sharpening of all edge tools is much the same: shape the edge (with a file or grinder); hone it (with an oil- or water-stone); then strop it (with a leather strop, MDF polishing board, or even the flabby bit of the hand). With good steel and flat stones, this process will yield the sharpest of edges every time—sharp enough to shave the hairs off your head with feather-like pressure.
All stones, be they waterstones or oilstones, are required to be of the utmost flatness before they can be used for sharpening. Thankfully, there is a simple and utterly reliable method for accomplishing this.
Procure three stones of equal or similar grit and hardness; label these 'A', 'B', and 'C' with a permanent marker at one end of each of their long edges. Also mark the back sides of each stone with an 'X' in the middle (we only need to use one face). These marks will make it possible to identify each stone and also orient them end-to-end in a repeatable fashion.
The flatttening process involves wearing every stone against every other stone in a cycle that ensures that, gradually as it's repeated many times, the high and low areas of each stone are "reduced to grade". This grade is a truely flat surface, and can form the reference against which all tool edges can be measured. (Note that this process does not work with two stones only, and nor does it need more than three.)
To begin, take stones A and B in your left and right hands respectively and with the lettered-edges uppermost. Rub the front faces of these stones together. Quickly, the high points of each stone will be visible as the areas that are being worn away first. Don't try to extend these areas too far yet (this is a process that should be gradual), but instead start to even out the inevitable unevenness of your hand pressure by rotating stone 'B' so that it's label is now facing down and at the closer end of the stone. Rub again in this position. Perhaps 10 forward-and-backward motions in each of these two positions are all that are required; perhaps even fewer, depending on the hardness of your stones.
Next, put down stone 'A', swap stone 'B' to your left hand, and take up stone 'C' with your right. 'B' and 'C' should now be as 'A' and 'B' were when you began, and what you did with them you must now exactly do with this new pair.
There's a pattern here, of course: after wearing B and C togther, you move on to C and A — and this is the last step in the cycle before you begin again. Not also that this third time, A is in your right hand (whereas before it was in your left) and this is also part of ensuring that your muscular inequalities do not have inequal effect on the stones.
Carry on in this fashion — A-B, B-C, C-A, A-B, etc. — and slowly the stones will come to match each other's sufaces and in doing so will be perfectly flat.
This section is concerned with traditional English-style handsaws that cut on the push stroke (as opposed to, for example, Japanese saws).
All work on saws should be done with the saw held firmly in a saw vice, to stop blade flex and chatter; these are annoying and shorten the life of the files. There are many different types of vice, from commercial cast-iron cam-operated models, to the simplest method of two pieces of timber held either side of the blade. Clamp the saw blade in the vice about with about 3 or 4mm of blade showing (below the gullets of the teeth).
Jointing is the process of filing all of a saw's teeth down to a common line, and needs be done only when the teeth are uneven or incorrectly shaped.
Correcting the profile of the teeth.
Bending the teeth out to each side of the blade about ¼ the thickness of the blade.
Actually putting the cutting edge to the teeth, working from alternating sides and filing towards the handle.