Grinding A Drill

To grind a drill it is placed on the toolrest or it may be held free from the rest against the face of the grinder at about 59 degi, as shown in Figures 45 and 46. The cutting lip of the drill (A, Fig. 46A) is held against the stone, and the drill turned slightly to the right so that a lip clearance (B, Fig. 46A) is obtained by grinding the heel slightly lower than the cutting lip. By turning the drill, the lip clearance surface is made slightly rounding. This is preferable to a flat surface because it makes a stronger backing for the cutting lip and thus will stand more severe usage.

To test the angle of the cutting W fJ lips, a tin template is very useful, y rJ The dimensions for the template

V y placed on the cutting lips as shown

If the drill is ground correctly, [/ each cutting lip will cut a spiral fig. 40. the drill is held hori- coil of metal as it is forced into the zontally against the grinder •

at 59 degrees. 11 On.

carr/ncf lip dcad cchter

7h£ //stzl (3 l.ow/£ft. „ WW 77V/T cutt/hg up 7?.

fig. 46a. how to grind a drill

tin template co#/t£ctly o/tour/o. ¿//=> cl£/9##f*ce

7h£ //stzl (3 l.ow/£ft. „ WW 77V/T cutt/hg up 7?.

fig. 46a. how to grind a drill carr/ncf lip dcad cchter

tin template

III. Small Saws

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