Pilot Hole Size For 8x32 Machine Screw

pin holes drilled after which the blade is hardened and drawn at dark straw color, then the sides ground flat and true by rubbing on an oil stone, arid the cutting edges whetted. The pilot is also of tool steel, turned to shape and the end slotted on milling machine; then it is hardened, ground and polished to exactly .300 inch. It is attached to the cutting blade by two small screws as shown in cut. The handle is then made from machine steel, slotted and attached to the blade. To use place the barrel in vise with muzzle slightly lowered, so that no chips may work in against the pilot, and turn by hand. Finish by lapping inner edge of cut true with a 5/8" brass ball, as described in Chapter 24.

Brass balls, for lapping and trueing barrel muzzles, should be obtained in the following sizes:—3/8, 1/2, 5/S and 3/4 inch diameter. Get at least two of each size in case you spoil or lose one. Drill a little more than half way through each ball with a No. 29 twist drill, and tap the hole 8x32; turn in a screw 1 inch long, cut off the head, and use the screw as a shank for holding.

CLAMFS: For attaching horn, ebony, ivory or other .foxend tips, there are two special types of clamp, known as the long C-damp, and the Y-clamp or fork clamp. Figure 28 A shows the long C-clanip, which is made of a piece of 3/4x5/8 inch cold rolled steel heated and bent as shown, and one end drilled and tapped to receive a standard 3/8 inch cup-point set screw 3 inches long. These clamps may be made any length required, so that one end is in-

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