7.8 mm 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.

Black/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	Mfr.		Each
Jobbers' Length







				Black Oxide

				7.8	0.3071"	117	59.4	Round	7.8 mm	Standard	Dormer Pramet	2958A125	00000




						Black/Gold Oxide

						7.8	0.3071"	114	79.8	Round	7.8 mm	Split	Viking Norseman Drill	30565A303	0000

Cobalt Steel Drill Bits


Jobbers' 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.

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	Mfr.		Each
Jobbers' Length







				Titanium Nitride (TiN) Coated

				7.8	0.3071"	117	75	Round	7.8 mm	Split	Dormer Pramet	5058N137	000000




						Gold Oxide

						7.8	0.3071"	117	59.4	Round	7.8 mm	Split	Dormer Pramet	29355A128	00000

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	Mfr.		Each
Jobbers' Length







				Uncoated

				7.8	0.3071"	117	73	Parabolic	Round	7.8	Split	Viking Norseman Drill	2771N776	000000

Undersized Hardened Multipurpose M2 High-Speed Tool Steel Rods

These rods, also known as drill blanks, have an undersized diameter for machining your own drill bits. They're hardened for increased abrasion and impact resistance. M2 tool steel offers a nice balance of wear resistance and machinability. It has a high molybdenum content, which allows it to maintain sharp cutting edges even at elevated temperatures.

Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.

Dia., mm	Dia. Tolerance, mm	Drill Bit Size, mm	Lg.	Yield Strength	Hardness	Mechanical Finish		Each
7.8	-0.005 to 0	7.8	4 1/2"	Not Rated	Rockwell C60 (Extra Hard)	Precision Ground	2900A356	00000