REMAKING HISTORY
By William Gurstelle,
Workshop Warrior
THE OLIVER:
A LEG-POWERED
HAMMER
Build the treadle hammer
that helped build medieval Europe.
; A medieval-style foot-operated Oliver hammer, from
The Practical Metal Worker’s Assistant by Oliver Byrne
(no relation to the hammer), 1864.
If you examine the nails holding medieval
European buildings together, you’ll find they’re
different from the nails available today. They’re
better. Today, nails are machine-sliced from a
strand of hardened wire and the cross section
is round; when you pound one into wood, you
force it between the individual fibers. Such
nails work adequately in softwoods like pine,
but often split hardwoods like maple or walnut.
The medieval iron nail is an entirely different
animal. Each nail was wrought, that is, beaten
into shape by hammer blows. The cross
section of a wrought iron nail is rectangular,
with a hand-filed chisel point that doesn’t
simply push wood fibers aside; it actually
cuts through them. Wrought nails can even
be driven into oak without splitting it, and once
in, they’re nearly impossible to remove.
Of course, wrought nails, like just about
everything else a blacksmith made, required
a lot of muscle. To make a nail, the smithy
heated a bar of iron to red-hot in his forge.
Then he hammered the bar until it formed a
point. Then he reheated the nail and, using
a special tool, upset the other end with an
even bigger hammer to form the nail head.
This technique was invented by the Romans
and continued until a nameless but clever
14th-century blacksmith in the north of
England came up with a way to substitute the
large muscles in his legs for the relatively puny
muscles in his arms. This invention, the Oliver,
revolutionized ironworking in Europe. It’s a
small lift-hammer that uses a sapling (the
holly tree was preferred by English smiths) as
a tension spring to raise a hammer that pivots
on an axle. The hammer is then pulled down
by a foot-operated treadle to strike.
In the 18th century, water- and steam-powered hammers made the tree-branch
“spring pole” obsolete. But for about 500
years the Oliver was one of the most important machines in the world and allowed nails
and other precious bits of ironwork to be
made faster and less expensively.
In this project, we’ll make a tabletop model
Oliver that uses a hand-treadle.
START
1. Begin by removing any grease from the
black iron pipe with household cleaner. After
the pieces are clean, you can lightly reapply
pipe grease to the pipe threads if necessary.
2. Assemble the treadle and hammer frame
according to Figure A. Start at the bottom,
with the flanges, and work your way up. Take
note that some connections are to be screwed
together tightly and others left loose.
Because all the pipe threads are right-handed, you may find it difficult to screw the
last nipple into the last elbow. To work around
this, over-tighten the nipple in its tee fitting on
the other side, move it into place between the
tee and elbow. Then tighten the nipple into the
elbow while loosening its connection into the
170 Make: makezine.com/30
