Backsaw
From Wikipedia, the free encyclopedia
A Backsaw is any of several types of hand saws used in woodworking which have a stiffening rib on the edge opposite the cutting edge, allowing for better control and more precise cutting than with other types of saws. Backsaws are normally used for precise work, such as cutting dovetails, mitres, or tenons in cabinetry and joinery. Because the stiffener is thicker than the blade, the backsaws are limited in the depth to which they can cut. Backsaws usually have relatively closely-spaced teeth, often with little or no set.
The origin of the Western backsaw is unknown, but it dates at least to Roman times. The Japanese Dozuki, itself a type of backsaw, is likely to have a different origin to the Western version however it shares common characteristics.
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[edit] The backsaw family
Backsaws include the tenon saw, the dovetail saw, the (United Kingdom) sash saw1 and the gent's saw. Tenon and dovetail saws usually have a pistol grip style handle which may be open or closed at the bottom. The gent's saw has a thin turned handle which is parallel to the blade. Some dovetail saws also have this style of handle.
Different types of backsaw include:
- Mitre saw — often referred to a large backsaw (20-30 inches or 60-90 cm) used either in a wooden mitre box or in a metal frame which allowed cutting mitres of any specified angle. Note that not all mitre saws are backsaws, and the electric mitre saw (or chop saw) has taken its place today.
- Tenon saw, or often just backsaw — a midsized backsaw used to cut tenons or in a mitre box. The saw derives its name from its use in the cutting of tenons for mortise and tenon joinery. Tenon saws are commonly available with rip-filed teeth for rip cutting and cross-cut for cutting across the grain. Teeth are relatively fine, with 13 teeth per inch being a common size.
- Sash saw — name that seems to have been used in the 18th and 19th century for a smaller tenon saw, used in fabricating window sashes. The term is also used currently to refer to a thin, flexible saw used to free sashes that have been painted shut.
- Dovetail saw — a small backsaw used to cut dovetails. Although most dovetail saw teeth are set for cross-cutting, a rip saw tooth pattern is more efficient. These saws will usually have a higher number of teeth per inch (around 15 T.P.I.) with teeth sharpened to favor ripping operations and set to leave a narrow kerf.
- Gent's saw or Gentleman's saw (rare) — a small dovetail saw with a straight turned handle, rather than an open one typical of most saws. The name seems to have arisen from its use by the nineteenth century dilettante who would now be called a hobbyist but it is hard to find a nineteenth century reference to it. For example, in the section on tools in Every Man his own Mechanic (1881) (816pp), tenon, dovetail and sash saws are listed as a group but there is no mention of a gent's saw. It is adapted for use in making joints in very small woodwork such as that in some musical instruments, dolls' furniture or other model-making. Its distinguishing features are its small size and turned handle.
- Razor saw — A very small backsaw having very finely-pitched crosscut teeth, often with no set. The Razor saw is used by hobbyists, notably Model aircraft, Model boat, and Model railroad enthusiasts. Razor saws typically use disposable blades, since their teeth are so small as to be impractical to re-sharpen.
- Dōzuki — a Japanese backsaw, used for centuries by carpenters and cabinetmakers in Japan. Although this saw does not share an ancestry with the other backsaws in this group, the concept is the same. Unlike most western saws, the dozuki cuts on the pull stroke.
[edit] The design
The work of a backsaw requires a thin, stiff blade. These two immediately incompatible requirements are resolved by swaging (and perhaps, spot welding) a stiffening cap over the length of the top edge of the blade. This thickening of the blade is the back and is generally made from some kind of metal, usually brass or steel. The stiffening back is carried through into the handle so that the blade does not bend between the two. The thickening of the back limits the depth to which the saw can cut but this is generally not a limitation in their typical uses.
[edit] Associated tools
- A backsaw is often used in combination with a mitre box to produce angled cuts.
- Another accessory commonly used is the bench hook.
- Another tool associated with the use of backsaws is the marking knife. This leaves a cleaner line than a pencil would and it cuts the fibres at the surface of the wood. Without this, the action of the saw would lift them and leave a ragged edge.
[edit] References
- Young, F. Every Man his own Mechanic (1881)
- Oxford English Dictionary (1978) ISBN 0-19-861212-5
[edit] Footnote
- Note 1: In North America, the name sash saw is used for a frame saw used in sawmilling.
