The New Spruce Forge Manual of Locksmithing: A Blacksmith’s Guide to Simple Lock Mechanisms

More hammering will create more fullers and the
result will be a section of bar that is thinner and
longer than the original bar stock.
To complete the fullering process it is necessary to
hammer all the high spots back into the bar. This is
done by returning the hammer to a vertical position
and hammering until the surface becomes smooth.
Driving these high spots back into the bar also forces
the metal to become longer.
The Process of Drawing Down
When you are forging a bar into a new shape, it is important to always do the fullering on a four-sided
forging regardless of the final shape you are trying to achieve. If the final shape happens to be square or
rectangular, then you can go directly to roughing out that shape. However, if the finished piece needs to be
round, you will need to start the process by creating a square bar before starting any fullering.
On a square or rectangular forging, any
irregularities in the size or shape of the bar can
be easily seen because you have only two planes
of reference to keep track of. The two sides of
the forging can be checked quickly by simply
rotating the bar 90-degrees. On a round forging,
missed hammer blows or thin sections can show
up anywhere around the circumference. This
makes it a lot harder to decide how to correct any
irregularities in the shape.
On a four sided shape the anvil always
creates a flat face that can be used as a
reference edge for the opposite side
Iregular shapes with multiple sides rarely
have a face that can be used as a reference
during the forging process
When you have the size and shape the way you
want it, you can turn the square into a round bar
by first hammering the corners of the square back
into the bar to create an octagonal shape, and
then hammering the corners of the octagon into a
hexagonal shape.
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