Classic_Boat_2016-08

CLASSIC BOAT AUGUST 2016 109

COMPASS SAW

STORY AND PHOTOGRAPHS
ROBIN GATES

A broad blade is a real boon when
sawing to a straight line because the

big plate of steel acts like a barn-door
rudder keeping the cutting edge on
track, but to follow a curve you need

a narrow blade which can be steered
left or right without binding in the

kerf – exactly as provided by the
compass saw.
This example scything through a

board of (recycled)^7 / 16 in Honduras
mahogany was made at the Ebenezer

Works of Sheffield saw makers
Drabble & Sanderson in the mid-19th
century. ‘London’ stamped on the

blade indicates London spring steel,
the highest quality saw steel then

available. An advantage of old
high-carbon saw steel is that its bite
can be restored with the touch of a

triangular saw file.
The 12 inch blade tapering from 1

inch width at the handle to^3 / 8 in at
the toe also has a pronounced taper
in thickness from cutting edge to

back, a feature imparting stiffness
while allowing the blade to heel

sideways in the kerf and be guided
around a bend. The curve is

maintained by applying a gentle and

constant sideways pressure, while

also keeping the blade perpendicular

to the face of the board, which

requires concentration.

The shapeliness of the handle was

not designed for looks alone. Good

control is essential for a narrow blade

which may wander off course as

easily as a canoe in a whirlpool if

hand and cutting edge are not in

constant communication. The swollen

grip which fills the palm and long

horns cosseting the heel make this

saw an extension of the worker’s arm.

Even so it is not uncommon to find a

compass saw that has sailed into a

head sea of hard grain and buckled; a

ripple in the steel will betray where

the kink has been beaten out.

Excepting where grain follows the

curve a compass saw must cut both

with and across the grain and this

need is reflected in its hybrid tooth

profile, having the steep face of a rip

tooth yet also filed to a point to sever

cross-running fibres. The ultimate

necessity for this lies in sawing a

circular aperture inside a board, which

is begun by boring a hole in the waste

large enough to insert the blade.

NEXT MONTH: Portable

woodworker’s vice

Clockwise from

above: the blade

heels sideways in

the kerf; cleanly

sawn to a 5in

radius; filing

the teeth

Traditional Tool