55mm Long Drill Bits | McMaster-Carr

Also known as screw-machine and stub-length bits, these provide maximum rigidity for drilling straighter holes than jobbers'- and maintenance-length drill bits.

Black-oxide drill bits produce less friction than uncoated drill bits.

Titanium-nitride (TiN) coated drill bits last longer and can drill at higher speeds than uncoated and black-oxide drill bits.

Drill bits with a split point keep centered without a pilot hole.

For technical drawings and 3-D models, click on a part number.

				Shank					Each
Drill Bit Size	Decimal Size Equivalent	Overall Lg.	Max. Drilling Dp.	Type	Size	Point Style	Specifications Met	For Use On		Each
Metric
Black-Oxide High-Speed Steel
4.0 mm	0.1575"	55mm	13.9mm	Round	4mm	Split	DIN 1897	Steel, Iron, Stainless Steel	00000000	00000
4.1 mm	0.1614"	55mm	10.2mm	Round	4.1mm	Split	DIN 1897	Steel, Iron, Stainless Steel	00000000	0000
4.2 mm	0.1654"	55mm	13.5mm	Round	4.2mm	Split	DIN 1897	Steel, Iron, Stainless Steel	00000000	0000
Titanium-Nitride (TiN) Coated High-Speed Steel
4.1 mm	0.1614"	55mm	10.2mm	Round	4.1mm	Split	DIN 1897	Steel, Hardened Steel, Tool Steel, Iron, Stainless Steel, Nickel, Aluminum, Brass, Bronze, Plastic	0000000	0000

Smooth-Finish Carbide Drill Bits

Three cutting edges instead of the typical two enable these bits to drill holes with a smoother finish than other bits. Made of solid carbide for the highest accuracy and longest tool life, they are harder, stronger, and more wear resistant than high-speed steel, cobalt steel, and carbide-tipped bits. They retain a sharp, hard edge at high temperatures for the best performance on hard and abrasive material. These bits require rigid toolholding to prevent breakage and should not be used in hand-held drilling. All are jobbers’ length so they have the rigidity and length required for most applications. A split point keeps the bit centered without a pilot hole.

For technical drawings and 3-D models, click on a part number.

				Shank
Drill Bit Size	Decimal Size Equivalent	Overall Lg.	Max. Drilling Dp.	Type	Shank Size	Point Style	For Use On		Each
Metric
Uncoated Carbide
4.0 mm	0.1575"	55mm	21.9mm	Round	4mm	Split	Steel, Iron, Stainless Steel, Aluminum, Brass, Bronze, Plastic	000000	000000
4.2 mm	0.1654"	55mm	21.9mm	Round	4.2mm	Split	Steel, Iron, Stainless Steel, Aluminum, Brass, Bronze, Plastic	0000000	00000

Diamond-Coated Router Bits for Composites

Drill/Mill Cut Style

Straight Flute

With a diamond coating, these bits resist wear when used on abrasive materials, making them last about 50 times longer than uncoated bits. Their sharp cutting edges and flute shapes are specifically designed to cut through tough materials such as composites with minimal resistance. This means less strain on your router and more control when cutting, leading to a smooth cut. Bits are made of solid carbide for longer tool life and faster cutting speeds than high-speed steel.

Straight Flutes—For general purpose use. They quickly remove material, leaving a rough finish.

Bits with a drill/mill cut style have a pointed end for easier plunge cuts than square-cut bits.

Plunge-cutting bits let you cut directly into the workpiece from above. Other bits are best for operations where the peripheral teeth do most of the work such as trimming, contouring, and finishing.

For technical drawings and 3-D models, click on a part number.

Diamond-Coated Carbide
Cutting Dia.	Lg. of Cut	Shank Dia.	Overall Lg.	Number of Flutes	Cut Type	For Tool Type	For Use On		Each
Straight Flutes with a Drill/Mill Cut Style
4mm	12mm	4mm	55mm	6	Plunge	CNC Machine	Fiber-Reinforced Plastic	0000000	0000000