31.0 mm Drill Bits | McMaster-Carr

Cut large holes with drill presses and portable drills that have a standard-size chuck. The shank on these bits has a smaller diameter than the cutting tip. High-speed steel is good for general purpose drilling in most metals. Also known as Silver and Deming bits.

Jobbers' Length—These bits have the balance of rigidity and length needed for most applications.

Black Oxide—The dark finish increases wear resistance and reduces friction to improve chip flow, so these bits can last 50% longer than uncoated bits.

					Shank
	Drill Bit Size, mm	Decimal Size Equiv.	Overall Lg., mm	Max. Drilling Dp., mm	Type	Size	Drill Bit Point Type		Each
Jobbers' Length





				Black Oxide

				31.0	1.2205"	152	53.3	Reduced Round	1/2"	Standard	3091A68	0000000

High-Speed Steel Step Drill Bits

Standard

Drill multiple hole sizes using only one bit. These have steps with progressively larger diameters—the deeper they drill, the bigger the hole. Count the steps as you drill to achieve the proper size. These bits also deburr as they cut, so they're good for thin materials like sheet metal and plastic panels. Wear and heat resistant, high-speed steel is versatile for use on a range of materials.

Uncoated—The most economical option, uncoated bits perform best when used on low-carbon steel and aluminum. Polished to reduce friction, they're also known as bright finish bits.

			Shank
Drill Bit Size, mm	Decimal Size Equiv.	Overall Lg., mm	Type	Size	Drill Bit Point Type		Each





			Uncoated

			5.0, 7.5, 10.0, 13.0, 16.0, 19.0, 21.0, 23.0, 26.0, 29.0, 31.0, 33.0, 35.0	0.1968", 0.2953", 0.3937", 0.5118", 0.6299", 0.748", 0.8268", 0.9055", 1.0236", 1.1417", 1.2205", 1.2992", 1.378"	79	Hex	11.1 mm	Standard	89275A15	000000

High-Speed Steel Drill Bits

Jobbers' Length

Morse Taper Shank

Standard

Our basic drill bits are also the most versatile. Cut holes in a variety of metals, from the softest aluminum to the hardest steel.

Jobbers' Length—These bits have the balance of rigidity and length needed for most applications.

Black Oxide—The dark finish increases wear resistance and reduces friction to improve chip flow, so these bits can last 50% longer than uncoated bits.

					Shank
	Drill Bit Size, mm	Decimal Size Equiv.	Overall Lg., mm	Max. Drilling Dp., mm	Type	Size	Drill Bit Point Type		Each
Jobbers' Length





				Black Oxide

				31.0	1.22"	301	124	Morse Taper	Morse 3	Standard	3070A96	0000000