Re: On Sharpening Bow Saws
Turba, Thomas N RV (tnt1@PO11.RV.UNISYS.COM)
Tue, 10 Dec 1996 13:07:00 -0600
I was thinking of this the other week and happened to run into a FAQ on
woodworking tools. The following is an abbreviated snippet. The full copy
is found at:
How do I sharpen saw blades?
TOOLS for Saw Sharpening: Saw file and vice
The saw file has three equal faces, an equilateral triangle in
cross section. Any hardware store will have them.
You need something to hold your saw while you file it. Called a saw
vice, this is just a vice with a very wide pair of jaws. You can make
one from two scraps of plywood, a hinge to hold them together, and
some rubber to face the plywood with so the process is quieter. Clamp
the saw vice in your bench vice.
Old saw vices are around used, but they are becoming harder to find
and really don't work any better than the wood vice you can make.
THE SHARPENING PROCESS
Basically you just file each tooth the same amount, in the same
direction the old tooth was filed. Rip saws are usually sharpened
with all teeth chisel cut, not skewed to the blade. Crosscut saws
have each alternating tooth skewed to the blade, by about 15 degrees.
Every few sharpenings you will want to "set" the teeth as explained
below, and once every life time you may need to "joint" it, also
Jointing the Saw (optional)
Start with teeth that are roughly the same height. If they are, skip
If the saw has been sharpened a lot, sometimes a dip or bump in the
height of the teeth develops, which should be corrected by "jointing"
the saw. Jointing is done by simply filing the tops of the teeth
level with an ordinary smooth file, held in a little guide to keep it
perpendicular to the blade. Then proceed to set the teeth and sharpen
Setting the teeth (Optional)
The teeth on panel saws are set alternately, that is each tooth is bent
slightly away from the plane of the blade with a tool called a "saw set"
or a hammer and anvil. This set makes the kerf wider than the blade
so the saw can move through the cut freely.
You won't need to set the teeth every time you sharpen, but if the saw
is clean and binds in the cut, it's probably time to set it.
I'll assume you have a saw set which allows you to dial the amount of
set based on the tooth pitch (4,5,6,...). Once adjusted for the pitch,
the saw set is used to bend every other tooth one direction, the saw is
reversed in the vice and the remaining unset teeth are set.
Don't buy a new saw set; they are very common on the used tool market
and cost much less than new ones.
FILING the TEETH
The goal here is to take off just enough metal to put an edge on the
tooth. Two to four strokes per tooth should do it. Use the same file
and the same number of strokes on each tooth. When sharp, the teeth
lose the shiny flat on the tip, and have just an edge.
As I mentioned, crosscut saws have angled teeth, while rip saws have
chisel cut teeth. For rip saws, the file is perpendicular to the blade.
For crosscuts, follow the angle on your saw teeth now. It is usually
skewed about 15 degrees from perpendicular for crosscuts, and slightly
pointed on the outer edge of the tooth. Hold the saw file at a
consistent angle, sloped a little and skewed a little to match the
angle of the existing teeth. It should take less than an hour to
sharpen your saw.
Try your newly sharpened saw and you will be amazed at the difference
in effort and quality of cut you can make with a sharper saw.
I hope this helps.
T. N. T.
Thomas N. (Tom) Turba
ASM Troop 297 (among other things)
E-mail: email@example.com (primary) -or-
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Terry Howerton Sakima Group, Inc. SCOUTER Magazine Kansas City