51mm Long Drill Bits | McMaster-Carr

Titanium Nitride (TiN) Coated—Drill at higher speeds and last longer than uncoated and oxide-coated bits, especially on tough materials like hardened steel and nickel.

Gold Oxide—Like black oxide, this finish adds wear resistance and reduces friction for improved chip flow. Because it’s less prone to flaking off, it offers better rust protection when bits aren't in use.

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	Max. Drilling Dp., mm	Type	Size	Drill Bit Point Type	Pkg. Qty.		Pkg.
Jobbers' Length





				Gold Oxide

				1.65	0.065"	51	22.2	Round	1.7 mm	Split	1	30565A225	00000
				1.65	0.065"	51	22.2	Round	1.7 mm	Split	10	30565A416	00000
				1.7	0.0669"	51	22.2	Round	1.7 mm	Split	1	30565A226	0000
				1.75	0.0689"	51	22.2	Round	1.8 mm	Split	1	30565A227	0000
				1.8	0.0709"	51	22.2	Round	1.8 mm	Split	1	30565A228	0000
				1.9	0.0748"	51	22.2	Round	1.9 mm	Split	1	30565A231	0000
				2.0	0.0787"	51	22.2	Round	2 mm	Split	1	30565A233	0000
				2.0	0.0787"	51	22.2	Round	2 mm	Split	10	30565A417	00000




						Uncoated

						1.7	0.0669"	51	25.4	Round	1.7 mm	Standard	1	2951A122	0000
						1.75	0.0689"	51	25.4	Round	1.8 mm	Standard	1	2951A123	0000
						1.8	0.0709"	51	25.4	Round	1.8 mm	Standard	1	2951A124	0000
						1.9	0.0748"	51	25.4	Round	1.9 mm	Standard	1	2951A126	0000
						2.0	0.0787"	51	25.4	Round	2 mm	Standard	1	2951A127	0000


						Short Length





										Titanium Nitride (TiN) Coated

										3.5	0.1378"	51	20.1	Round	3.5 mm	Split	1	2979N18	0000

Chip-Clearing Cobalt Steel Drill Bits

Jobbers' Length

Parabolic Flute

Round Shank

Split

Avoid clogs and dissipate heat with cobalt bits that last at least twice as long as high-speed steel. The flutes clear chips to improve coolant flow and prevent damage to the bit and the hole. They also speed up drilling since you don't have to stop to clear the bit manually.

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

Uncoated—Polished to eject chips, these are also known as bright finish bits.

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





				Uncoated

				1.75	0.069"	51	25	Parabolic	Round	1.75	Split	2771N712	00000
				1.8	0.0709"	51	25	Parabolic	Round	1.8	Split	2771N713	0000
				1.9	0.0748"	51	25	Parabolic	Round	1.9	Split	2771N714	0000
				1.95	0.0768"	51	25	Parabolic	Round	1.95	Split	2771N715	0000
				2.0	0.0787"	51	25	Parabolic	Round	2	Split	2771N43	0000

Left-Hand Cobalt Steel Drill Bits

Jobbers' Length

Round Shank

Split

The flutes spiral in the opposite direction of other bits and stay sharp longer than high-speed steel. They’re primarily used to remove stripped screws. Choose a bit that’s slightly smaller than the diameter of the screw’s head. Set your power tool to rotate in reverse. Slowly drill in the center of the screw head, maintaining constant pressure. As the bit penetrates, it will catch onto the screw and reverse it out of the hole. If the screw is badly stripped, you might need to punch a starter hole. Also known as reverse-flute bits.

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

Uncoated—Polished to eject chips, these are also known as bright finish bits.

					Shank				Each
	Drill Bit Size, mm	Decimal Size Equiv.	Overall Lg., mm	Max. Drilling Dp., mm	Type	Size	Drill Bit Point Type		1-9	10-Up
Jobbers' Length





				Uncoated

				2.0	0.0787"	51	25	Round	2 mm	Split	3474A49	00000	00000