CHAPTER XX.

=HAND-DRILLING AND BORING TOOLS, AND DEVICES.=

=The Brad-awl= 452 =Bits.= The gimlet bit 452 The German bit 452 The nail bit 452 The spoon bit 452 The nose bit 453 The auger bit 453 Cook's auger bit 453 Principles governing the shapes of the cutting edges of auger bits 453 Auger bit for boring end grain wood 453 The centre bit 454 The expanding bit 454 =Drills.= Drill for stone 454 The fiddle drill 455 The fiddle drill with feeding device 455 Drill with cord and spring motion 455 Drill stock with spiral grooves 455 Drill brace 455 Drill brace with ratchet motion 456 Universal joint for drill brace 456 Drill brace with multiplying gear and ratchet motion 456 Breast drill with double gear 456 Drilling levers for blacksmiths 457 Drill cranks 457 Ratchet brace 457 Flexible shaft for driving drills 458 Drilling device for lock work 459 Hand drilling machine 459 =Slotting Machine= 459 Sectional view of 460 Tool holders 460, 461 Tools 461, 462