Fig. 1106.
For reaming the bores of rifles, a square reamer, such as shown in [Fig. 1106], is employed; the edges a b are the cutting ones, the edges c d being rounded off; e is a piece of wood, beneath which slips of paper are placed to restore the size as the wear proceeds. The entering end of the reamer is slightly tapered. On account of the extreme length of this reamer in proportion to its diameter, it is fed to its cut by being pulled instead of pushed as is usually the case, the pull placing the rod of the reamer under tension and thus stiffening it; the line of pull is of course true with the axis of the rifle bore. The reamer is revolved at high speed and freely supplied with oil.
By means of the slips of paper successive cuts and minute increases of diameter may be taken with the same reamer.
Fig. 1107.
[Fig. 1107] represents a class of rose bit employed to reduce pins to a uniform diameter, and face off the shoulder under the head, or it may be used to cut a recess round a pin, or to cut a recess and leave a pin.
