Do not try to file the edge of the cutter to a knife fine edge; simply file away the metal raised by the shears when cutting. If it is cleanly cut and filed to the original thickness of the tin, it will cut biscuit dough very well, as the tin is thin.
Punching a Hole in Tin.—A hole should be punched in the top of the biscuit cutter to admit air, as the biscuit dough is apt to stick in the cutter by the vacuum formed unless an air vent is provided. A small hole about ⅛ inch in diameter will do, but a series of such holes may be punched in if desired.
A punch may be filed up from a wire nail or a regular punch or nail set may be used.
The biscuit cutter is placed over the end of a block of wood held in a vise as shown in [Fig. 9], in such a manner that the top of the cutter rests directly on the wood. The punch is placed in the center of the cutter, care being taken to see that the wooden block supports the tin directly under the punch, and then the punch is struck lightly with the hammer until it cuts through the tin.
It may be well to try the punch on a scrap of tin to test it. A clean round hole should result. The punch cuts out a tiny disk of tin and drives it into the wood. The end grain of a wooden block should always be used for punching on.
If a nail is used for a punch, the original point should be filed away. Nail points are usually made in the form of a square pyramid and if these points are driven into a piece of tin a jagged hole will result; such a hole may be used for making a grater for the kitchen, but all other holes should be round and smooth.
To file up a nail for a punch proceed as follows: Place the nail vertically in the vise jaws so that the point projects slightly above the jaws. File the point entirely away until you are filing the entire diameter of the nail and squarely across it.
Then reduce the diameter of the nail at the end you have been filing by filing smoothly around it as shown at A, [Fig. 10]. See that the edge B is clean and sharp and the nail punch is ready for use. The nail used for a punch should always be somewhat larger in diameter than the punching point, as this will provide for a stronger punch and one not so likely to bend. Regular punches are usually made much thicker in the body than at the point, as may be easily seen by looking at one. If desired, punches may easily be made from nails to cut round, square, or triangular holes.
