79mm Long Drill Bits | McMaster-Carr

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.

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.

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





				Gold Oxide

				3.9	0.1535"	79	47.6	Round	3.9 mm	Split	30565A259	00000


				Short Length





								Black Oxide

								8.0	0.315"	79	20.9	Round	8 mm	Split	28255A53	0000
								8.1	0.3189"	79	37	Round	8.1 mm	Split	28255A122	0000
								8.4	0.3307"	79	37	Round	8.4 mm	Split	28255A123	0000
								8.5	0.3346"	79	20	Round	8.5 mm	Split	28255A55	0000




										Titanium Nitride (TiN) Coated

										8.0	0.315"	79	38.1	Round	8 mm	Split	2979N28	0000
										8.5	0.3346"	79	38.1	Round	8.5 mm	Split	2979N29	00000

Cobalt Steel Drill Bits

Jobbers' Length

Round Shank

Short Length

Round Shank

Split

Tough and wear resistant, cobalt steel bits last at least twice as long as high-speed steel. They can also run up to 25% faster at higher temperatures without being damaged on hard materials, such as nickel.

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

Short Length—The most rigid bits for drilling the straightest holes.

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.

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	Type	Size	Drill Bit Point Type		Each
Jobbers' Length





				Titanium Nitride (TiN) Coated

				4.5	0.1772"	79	47	Round	4.5 mm	Split	5058N63	00000




						Uncoated

						3.9	0.1535"	79	47.6	Round	3.9 mm	Split	29355A63	0000


						Short Length





										Titanium Nitride (TiN) Coated

										8.0	0.315"	79	21.1	Round	8 mm	Split	2456N158	00000
										8.5	0.3346"	79	20.1	Round	8.5 mm	Split	2456N159	00000




												Uncoated

												8.0	0.315"	79	21.1	Round	8 mm	Split	2456N131	00000
												8.5	0.3346"	79	20.1	Round	8.5 mm	Split	2456N132	00000

Carbide-Tipped Drill Bits

Jobbers' Length

Round Shank

Short Length

Round Shank


Standard	Split

Performance similar to solid carbide but at a lower price point. Like carbide bits, these are stronger than cobalt and high-speed steel and maintain their sharp edges when drilling abrasive material. However, when drilling tough metals like iron and hardened steel, upgrade to carbide for longer life.

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

Short Length—The most rigid bits for drilling the straightest holes.

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





				Uncoated

				3.3	0.1299"	79	44	Round	3.3 mm	Split	28595A19	000000
				3.3	0.13"	79	41.9	Round	3.3 mm	Standard	28595A44	00000
				3.5	0.1378"	79	41.9	Round	3.5 mm	Standard	28595A46	00000
				3.5	0.1378"	79	44	Round	3.5 mm	Split	28595A21	00000
				4.0	0.1575"	79	41.9	Round	4 mm	Standard	28595A51	00000
				4.0	0.1575"	79	54	Round	4 mm	Split	28595A22	00000


				Short Length





								Uncoated

								9.0	0.3543"	79	27	Round	9 mm	Standard	28805A414	00000
								9.5	0.374"	79	28.5	Round	9.5 mm	Standard	28805A415	00000

Coolant-Fed Carbide Drill Bits

Maintenance Length

Round Shank

The hardest and most wear-resistant bits, these deliver coolant to reduce heat and evacuate chips. They are designed for CNC machines that supply coolant through the spindle rather than an external source, such as a hose and nozzle. Coolant flows directly from holes in the bit's tip onto the drilling surface. This speeds up cuts and leads to excellent performance in deep holes and tough materials such as stainless steel and titanium.

Maintenance Length—Shorter than jobbers' length, these bits are more rigid for less wobble when drilling hard material. Also known as mechanics’ bits.

Titanium Aluminum Nitride (TiAlN) Coated—No drill bits last longer. These are the best for high-speed, high-temperature drilling of very hard and abrasive materials, including titanium and fiberglass.

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





				Titanium Aluminum Nitride (TiAlN) Coated

				7.0	0.2756"	79	34	Round	8 mm	Four Facet	2396N679	000000
				7.5	0.2953"	79	40.9	Round	8 mm	Four Facet	2396N695	00000
				8.0	0.315"	79	40.9	Round	8 mm	Four Facet	2396N713	00000

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

Hole-Starting Cobalt Steel Drill Bits

120° Point Angle

Standard

Create an accurate starting place in your workpiece. Cut an indent with these bits, then continue drilling with a longer bit. The indent prevents slipping so the final hole is centered and precise. Cobalt steel resists wear to stay sharp when cutting hard materials, such as nickel. Also known as spotting drill bits.

Short Length—The most rigid bits for drilling the straightest holes.

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

					Shank			90° Point Angle
	Drill Bit Size, mm	Decimal Size Equiv.	Overall Lg., mm	Max. Drilling Dp., mm	Type	Size, mm	Drill Bit Point Type		Each
Short Length





				Uncoated

				8.0	0.315"	79	25.4	Round	8	Standard	27445A92	000000

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

				4.5	0.1772"	79	47	Parabolic	Round	4.5	Split	2771N52	00000