DIY Network

Drill Bits and Countersinks From "DIY Tools & Techniques" episode DIT-232

A look at different drill bits and their functions.

advertisement

	Figure A
	Figure B
	Figure C
	Figure D
	Figure E
	Figure F
	Figure G

Forstner Bit

A Forstner bit (figure A) can drill large holes. It has lifting flutes to dig in and drive into the material you’re cutting. A small spur in the bit shows you the center of the bit. When drilling with this bit, rock the drill back and forth slightly to drill more quickly.

Larger Forstner bits have sawtooth edges (figure B) The sawtooth edges cut faster and last longer than smooth-edged bits. Forstner bits work with on a drill press.

Spade bits

For smaller holes, spade bits are effective. They are also less expensive than Forstner bits. David shows two examples of spade bits. (figure C) The one of the left has a screw-like tip for cutting into hard woods.

Twist bits

Steel twist bits are also used for cutting small holes (figure D). They are low-angle fluted bits. You can get them in a range of sizes. These bits cut both wood and metal.

Some twist bits have a titanium coating. These bits cut through wood faster because the coating reduces friction. The coating also protects the cutting edge.

Brad point tip bit

Compare the tips on the titanium bit to a brad point tip bit (figure E) The titanium bit can chatter in hard woods. The brad point tip helps you find the center.

Countersinking bits

These bits cut pilot holes. They each have a fluted part at the top of the bit that countersinks, which means the hole for the screw is drilled, then a wider hole is left at the top to sink the head of the screw into the wood (figure F).

Metal Cutting Step Bit

This bit (figure G) cuts through sheets of metal. It cuts a lot of different holes at once. The deeper you go into the wood, the greater the diameter of the hole.

RESOURCES :

Craftsman Drill Press
Sears
Phone: 800-377-7414
Web site: www.sears.com/craftsman

Hitachi Drill
For free catalog, call: 800-829-4752
Website: hitachipowertools.com

Irwin Drill Bits and Drivers
Phone: 800-GO-IRWIN
Web site: www.irwin.com

Bosch Forstner Bit
Phone: 877-Bosch99
Web site: www.boschtool.com

Ridgid Tools
Phone: 800-4RIDGID
Web site: www.ridgid.com