The engineer's sketch-book of mechanical movements, devices, appliances, contrivances and details employed in the design and construction of machinery for every purpose

by Thomas Walter Barber

Section 30.—DRILLING, BORING, &c.

Besides the ordinary tools in use, as gimlets, bradawls, pin and brace bits, augers, &c., which do not need description, the following are noteworthy:—

[521]. Is the ordinary V drill for metal work.

[522]. Flat point, or “bottoming” drill.

[523] & [524]. Countersinking drills for metal.

[525]. Centre bit for wood.

[526]. Twist bit for wood; clears its own borings. There is a variety with rounded cutter edges.

[527], [528], & [529]. Rock drills, or “jumpers.”

[530]. Earth borer, or mooring screw.