Scratch round
plainly with a fine steel point.
To remove the metal for a tube hole, it is necessary to drill a succession
of almost contiguous holes as near the scratch as possible without actually
cutting it. When the ring is completed, join the holes with a cold chisel
held obliquely. Then file carefully with a round file, just not cutting the
scratch. As the side of the hole nearest to the bottom corner should run
obliquely to enable the tube to pass, work this out with the file held at
an angle.
As soon as a pair of holes (one in the bottom, the other in the side) have
been made, true up the side hole until a piece of tubing will run through
it at the correct angle. Then bevel off the end to 45 degrees and pass the
tube through again, bringing the bevel up against the bottom hole from the
inside. If it is a trifle difficult to pass, bevel off the edge slightly on
the inside to make a fairly easy driving fit. (Take care not to bulge the
bottom of the kettle.) Mark off the tube beyond the side hole, allowing an
eighth of an inch extra. Cut at the mark, and number tube and hole, so that
they may be paired correctly later on.
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