92
CLASSIC BOAT JUNE 2019
CRAFTSMANSHIP
Boatbuilder’s Notes
CUSTOM TOOL
Making a plane
screwdriver
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BY ROBIN GATES
Workers rediscovering the joys of old
wooden planes are often frustrated by the
mangled state of the chunky slotted
cheesehead screw which locks the blade and
back iron. Almost invariably the damage has
been done by a screwdriver that’s neither
wide nor thick enough to gain a good
purchase on the slot; every time the
undersize tip twists free it deforms the walls
of the slot, worsening the situation.
The solution is to make a screwdriver
shaped to fill the slot precisely, using an
old-style cabinet screwdriver as the starting
point – examples already ruined through
levering off the lids of tins of paint are easily
found for pennies. Step one is unavoidably
brutal: grip the blade in the vice and, just behind
where the shank turns from round to flat, cut
through using a hacksaw. File the sawn tip flat
and square, then hollow-grind the faces to
make a secure fit in the screw’s slot.
The second hand
supports the
screwdriver's shank
Two hands for
a screwdriver
Turning a screwdriver without mishap bears
comparison to playing a snooker shot, in that two
hands are required if you don't want to risk the
blade slipping and scoring the surrounding
surface – or the cue ploughing a furrow in the
baize. Using the two-handed technique, with one
hand to turn the tool and the other locating the
blade on the head of the screw, a right-hander
can work just as well left-handed and vice-versa.
Stoning
saw
teeth
There are two ways
in which a saw
manufacturer reduces
unnecessary friction
between the blade and the
timber. The first is to taper
the blade’s thickness, making it
progressively thinner towards the back.
The second is to apply set to the teeth,
that is to bend them alternately right
and left so as to cut a kerf that’s wider
than the blade is thick.
But if the set is too coarse, or uneven,
such as may be the case after hand-setting an old
saw using saw-setting pliers, the saw will cut a wastefully wide kerf,
or show a consistent bias in straying from the line. The set can be
improved by laying the blade flat on the bench and ‘stoning’ the
teeth by rubbing a whetstone lightly along each side.
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1 Saw the blade at the widest point 2 File the tip flat and square
3 Hollow grinding the faces 4 A snug fit in the slot