I restore and renovate historic hand and tenon saws from the 19th and 18th centuries. Sharpening is a part of the process.
Basic sharpening, on a saw that has just gone dull, is not difficult. Simple for rip-cut; a little more complicated for crosscut; quite tricky for fleam-cut.
But that is only rarely the case. Most saws are sharpened by their owners - the sawyers. Who are:
1: Either right-, or left-handed, or:
2: Lazy. So:
1: For right-handed sawyers, sharpening the front face of the teeth leaning AWAY [i.e: to the left, as you look along the toothline from the rear] is more natural and easier than sharpening those leaning to the right. So sawyers - who mostly sharpen from one side - sharpen more deeply on the one, than on the other. Over time and multiple sharpenings, every second gullet gets deeper than its fore-and-aft neighbours. So you get "Cow & Calf" teeth, with a small tooth "riding' on the back of the bigger tooth in front. If carried on long enough, the Calf tooth disappears, leaving the saw with toothing of half the original, and all leaning to one side. So the saw cuts in circles.
2: In sawing, the strongest thrust and therefore the greatest wear occurs around the midpoint of the stroke. Sawyers just want the saw sharp along its entire length, so tend to sharpen more intensively around the midpoint – rather than evenly, along the full length. Over time and multiple sharpenings, the sawline hollows. The result is that, towards the end of a stroke, the hollowed rear meets the wood, and brings the saw to an abrupt, jarring halt. Very uncomfortable.
The answer is Jointing – either half- or full jointing: filling off the tips of the teeth to generate a smooth [and ultimately a straight] toothline.
Half-jointing is for "Cow-&-Calf' teeth, and involves filing [with a long file, lengthways] along the points until the lowest teeth are just being touched. Then sharpening the protruding teeth, pushing sideways to right, then left, so the metal is removed from the larger tooth, leaving the smaller one barely touched. Once all the teeth have been sharpened to just remove the blunt points, the toothline should be correct, but may want resetting
Full jointing involves filing or grinding away the less-worn high parts of the toothline - typically the toe and particularly the heel - until sighting along the toothline shows straight. Then recutting the teeth from the high parts, and resetting the whole.
A light-to-medium sharpening of a blunt toothline in good order can take as little as 3 minutes; a heavy half-jointing can take an hour; a full jointing [particularly where the high zone teeth have completely disappeared, and need to be remarked out] can take half a day.
Basic sharpening, on a saw that has just gone dull, is not difficult. Simple for rip-cut; a little more complicated for crosscut; quite tricky for fleam-cut.
But that is only rarely the case. Most saws are sharpened by their owners - the sawyers. Who are:
1: Either right-, or left-handed, or:
2: Lazy. So:
1: For right-handed sawyers, sharpening the front face of the teeth leaning AWAY [i.e: to the left, as you look along the toothline from the rear] is more natural and easier than sharpening those leaning to the right. So sawyers - who mostly sharpen from one side - sharpen more deeply on the one, than on the other. Over time and multiple sharpenings, every second gullet gets deeper than its fore-and-aft neighbours. So you get "Cow & Calf" teeth, with a small tooth "riding' on the back of the bigger tooth in front. If carried on long enough, the Calf tooth disappears, leaving the saw with toothing of half the original, and all leaning to one side. So the saw cuts in circles.
2: In sawing, the strongest thrust and therefore the greatest wear occurs around the midpoint of the stroke. Sawyers just want the saw sharp along its entire length, so tend to sharpen more intensively around the midpoint – rather than evenly, along the full length. Over time and multiple sharpenings, the sawline hollows. The result is that, towards the end of a stroke, the hollowed rear meets the wood, and brings the saw to an abrupt, jarring halt. Very uncomfortable.
The answer is Jointing – either half- or full jointing: filling off the tips of the teeth to generate a smooth [and ultimately a straight] toothline.
Half-jointing is for "Cow-&-Calf' teeth, and involves filing [with a long file, lengthways] along the points until the lowest teeth are just being touched. Then sharpening the protruding teeth, pushing sideways to right, then left, so the metal is removed from the larger tooth, leaving the smaller one barely touched. Once all the teeth have been sharpened to just remove the blunt points, the toothline should be correct, but may want resetting
Full jointing involves filing or grinding away the less-worn high parts of the toothline - typically the toe and particularly the heel - until sighting along the toothline shows straight. Then recutting the teeth from the high parts, and resetting the whole.
A light-to-medium sharpening of a blunt toothline in good order can take as little as 3 minutes; a heavy half-jointing can take an hour; a full jointing [particularly where the high zone teeth have completely disappeared, and need to be remarked out] can take half a day.
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