DIYTimber cutting hand saws.pdf

Timber cutting hand saws

saw terminology - handsaw - flooring saw - tenon - many blades - padsaw

bow saw - coping - log - two-man crosscut

Although power saws are now widely available, there is still a place for a range of handsaws

in the tool kit of the do it yourself handyman, the model-maker and professional carpenter.

Sometimes the work site does not have electricity or a small job does not justify running an

extension lead for the connection. At other times, the often better control of a handsaw makes

its choice over a machine justified. The following describes some of the more common

handsaws available to the diy person.

General

Saw terminology

Measuring teeth : The teeth on saws are c

by a number which represents the number of teeth

points along 25.4mm (1 inch) of the cutting edge,

including those at each end. The number is

referred to so many points, the point size is one

greater than the teeth per inch (tpi). The teeth of

ripsaws are relatively large, usually between four

seven points. The larger tenon saws, say 30 to 40cm (12 in to 16 in), usually have teeth of 12

to 14 points. Smaller saws for general bench work also may have 14 points, but the smaller

saws intended purely for dovetailing may have teeth as fine as 22 or 24 points. Saws wit

teeth should be used only for fine work.

The set of the teeth : Most saws have their teeth "set"; that is, the teeth are bent outwards

slightly in alternate directions so that they make a cut slightly wider than the saw blade

thickness, this gives a clearance so that the main part of the blade is clear of the sides of the

cut. The set should not be excessive, as it will only mean that wood is being removed

unnecessarily, resulting in increased resistance in cutting and more sweat. To reduce the

necessity for the amount of set, some handsaw blades are taper ground, (that is the blade is

ground thinner behind the teeth), thus providing additional clearance with only a small degree

of set required. Saws used for green wood (i.e. freshly cut timber) have increased set as the

sawdust from green timber is inclined to cling to the blade.

The front angle of the teeth : The front of the teeth on some saws are straight across at

right angles to the blade, so they present the wood with

a series of chisel-like edges, this tends to give a rough

finish. Other saws have teeth bevel-filed at an angle

instead of being at 90 deg., the idea being that the

series of sharp corners severs the grain at each side,

the waste wood between crumbling away as sawdust.

lassified

h fine

The angle at which the teeth are

bevelled vary from about 45 (for

softwood) to 60 deg (f

hardwood).

The pitch angle of the teeth: The pitch angle of the teeth to the nominal root line of the

teeth, associated with this is the point angle - the combination of these two angles determine

the slope of the back of the teeth. A large number of modern handsaws have hardened teeth

to prolong their useful life; these saws are, to an extent, 'throwaway' tools as they cannot be

easily sharpened when they become blunt.

Handsaws . This general term includes several types, such as the rip, crosscut, and the

panel saw. They all look basically the same and their purpose is the cutting of timber from

boards, and sometimes making larger joints.

Ripsaw: The ripsaw is intended to cut along the grain. The front of the teeth are generally at

right angles to the blade and pitched at between 85 and 90 degrees to the blade. Some

ripsaw have incremental

teeth;

this is where the teeth

gradually becoming larger

point numbers) towards

(lower

the

handle.

The theory being that the

larger

teeth come into operation at

the

strongest part of the stroke.

Today

the DIY person seldom uses

the

manual ripsaw as timber is

available commercially in the widths required, or power circular saws

are available. For the odd occasions when it is required to rip out

timber, a cross- cut saw which, although not quite so satisfactory, is

quite adequate.

Lengths are taken along the run of the teeth from one end to the other, and are generally from

60 to 70cm (24 to 28 in).

Crosscut saws: These differ from ripsaws in that the teeth are bevel-filed at an angle

instead of being at 90 deg. Another way in which the crosscut saw teeth differ is that they are

pitched so that the front of the tooth makes an angle of 75 to 80 deg. with the line of the teeth.

Whatever the pitch, all teeth are pointed at 60 deg. The size of teeth varies from 6 to 12

points, and lengths of saw from 55 to 70cm (22-28 in).

Panel saw: This is simply a small version of the crosscut saw, from 45 to 60cm (18 to 24

in), and with smaller teeth of 10-12 points. It is used for cutting thin wood and for the larger

joints. Its teeth are pitched and bevelled as in the crosscut saw.

A feature common to all handsaws is tension. Without it the saw blade would be a flabby thing

with no natural stiffness. A tensioned saw remains stiff when waved sideways. Handsaws are

available with either straight-back or skewback. The straight back tend to have rather stiffer

blades, but there is little difference in their use.

Flooring saw. These tend not to be found in the tool kit of most DIY people as it is

somewhat of a specialist saw being used only to cut across floorboards so that they can be

lifted. The edge is curved, enabling a cut to be made across a board at the centre of a joist.

When the blade has penetrated, the straight part comes into use, the end of the saw being

narrow enough to enable it to enter a short cut.

Tenon saw. The technical name for saws that are stiffened along the back of the blade, is

Back Saws although they are generally referred to as Tenon Saws.

The length of blade can range from 20cm (8 in) up to 40cm (16 in), or even longer for special

work. Teeth of Tenon Saws are usually pitched at 75 deg., and small ones are bevel

sharpened at about 60 deg. because they have to cut across the grain as well as with it.

When, however, a tenon saw is to be used solely for cutting tenons the teeth may be straight

across at right angles because it always cuts along the grain and is therefore similar to a

ripsaw. As most people cannot keep a saw specifically for cutting tenons, the teeth are

generally bevel-sharpen. For fine work it is called a dovetail saw and may have very fine

teeth-22 to 24 points.

Larger Tenon Saws invariably have closed handles, smaller ones (dovetail saw) usually have

a' fist grip' handle - middle size saws tend to have 'pistol grip' handles.

Many blades - one handle. These have a number of interchangeable blades of which the

largest is usually a pruning blade, and the others a compass blade, and a keyhole blade. The

purpose of the last is obvious by its name, and the compass saw is used to cut curves on flat

sheet, the purpose of th

pruni

blade is

again obvious by its name.

Padsaw. Also known as a keyhole saw. Although intended primarily for cutting the straight

sides of a keyhole, it can be used for any internal cut, straight or curved. The blade is

adjustable in its projection from the handle, the idea being to enable it to be given as little

projection as is consistent with the required stroke. The saw necessarily relies upon the

stiffness of the blade to prevent it from buckling, but buckling can easily happen because of

the narrowness of the blade. The projection of the blade should always be kept to a minimum.

Bow saw. The Bow Saw is considered by many to be the most satisfactory saw for cutting

shapes since the narrow blade negotiates curves easily, and is held in tension. Both the

handle and knob (at the other end of the blade) can be turned so that a cut can be made

more or less parallel to the required cut. Obviously the blade must be free of twist when in

use. It is available with blade lengths of 25 to 40 cm (10 to 16 in). Generally both hands grips

the one handle, hence the bulbous shape with narrow neck, but when thick wood has to be

sawn it is helpful to have a person at each side, both sides of the wood having been marked.

In this way it is much easier to keep the cut square to the sides of the timber.

The rivets holding the blade to the handle can be withdrawn so that the saw can be used for

an internal cut, the blade being threaded through a hole drilled through the timber.

Coping saw. The Coping Saw is used for thinner wood and for fairly tight curves or shapes.

By turning the handle the tension of the blade can be slackened or increased. The blade can

be revolved through any angle convenient for sawing. Normally it cuts on the pull stroke, but

there are occasions when it is better to reverse the blade so that it cuts on the push.

Log saw. The Log Saw is intended only for crosscutting logs, etc., and has a metal frame.

The blade often has the lightning form of tooth shown and is fast cutting but leaves a ragged

finish. This is unimportant for the purpose for which the saw is intended.

Two-man crosscut. This saw is intended for sawing through large logs, and various

pattern teeth are used. Each tooth pattern is claimed to have its own particular advantages,

however this is often up to personal preference. Holes in the ends of the blade enable the

handles to be fitted. Lengths can be from about 120 to 240 cm (4 ft up to 8 ft).

Smaller versions of the saw used for the same purpose can be used by one person, but even

these usually have rivet holes at the toe end of the blade so that a second handle can be

fitted if necessary. These smaller saws tend to range from 90 to 110 cm (3 ft. to 4 ft. 6 in)

long.

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