I used a piece of an old file. Files are
made of good high carbon steel, and they can be used to make
various cutting tools, such as gouges and chisels. There are
several types of scrap steel with high carbon content that
can be used, but how does one measure it?
A quick test is to grind the metal and
observe the sparks it gives off. High carbon steel gives off
many sparks. Just touching it to the grinding wheel produces
a small “explosion.” Low carbon steel, in contrast, gives
off few sparks. In the photos I compare an ordinary bolt of
low carbon steel (above) with a piece of an old file
Another test to heat the metal to the point
at which it loses its magnetic attraction (cherry red),
quench it immediately in oil or water, then try to file it.
If after this hardening procedure the file skips, as if it
were sliding on glass, it is high carbon steel, which can be
hardened and tempered.
To test for the desired temperature,
simply touch it to a magnet while it is still cherry red.
When it does not stick it is hot enough to harden by
In an improvised forge made of bricks and a
propane torch I heated the metal to the cherry red
non-magnetic point, then let the piece cool in the air,
without quenching. This anneals the metal, so that it can be
To shape the “V” in the cutter blank I clamp
it in a vise and begin with a shallow hacksaw cut to guide
the triangular file used to finish the job. Then the
external shape of the “V” is formed. Interestingly, the
metal is very soft, making it impossible to sharpen the