20 mm Reamers | McMaster-Carr

Straight Flute—The most common flute style, these reamers are suitable for a wide range of applications, but not recommended for holes with a keyway or other breaks in the surface.

High-Speed Steel—Durable and wear resistant, these are good for general purpose reaming in most materials.

Cobalt Steel—With better heat and wear resistance than high-speed steel, these reamers run up to 25% faster, last longer, and perform better on hard materials, such as cast iron, hardened steel, titanium, and stainless steel.

			Lg., mm
	Reamer Dia.	Material	Flute	Overall	No. of Flutes	Cutting Dia. Tolerance, mm	For Use On		Each
Straight Flute







				Metric

				20.0000 mm	High-Speed Steel	63.5	241.3	8	0.0025 to 0.01	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	0000000	000000


				20.0000 mm	Cobalt Steel	63.5	241.3	8	0 to 0.005	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel, Tool Steel, Hardened Steel	00000000	000000

Square Shank

Spiral Flute

Turn these reamers by hand with an adjustable wrench or straight-handle tap wrench (sold separately).

Spiral Flute—Since these reamers clear chips better than straight flutes, they leave holes with a smoother finish. They're better for holes with breaks in the surface, such as a keyway, because they cut continuously across the breaks instead of moving in and out.

High-Speed Steel—Durable and wear resistant, these are good for general purpose reaming in most materials.

Left-Hand Spiral—These reamers push chips downward as they cut, so they're often used in through holes.

				Lg., mm
	Reamer Dia.	Material	Square Shank Size, mm	Flute	Overall	No. of Flutes	Spiral Direction	Cutting Dia. Tolerance, mm	Specs. Met	For Use On		Each
Spiral Flute







				Metric

				20.0000 mm	High-Speed Steel	16	100	201	8	Left Hand	0.009 to 0.017	DIN 206	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	0000000	0000000

Reamers for Hole Alignment

Enlarge holes to correct misalignment and overlap. Misaligned holes often have a narrow entry, so the tapered shape is easier to insert and makes more contact to remove the overlapping material. These are also known as bridge and car reamers.

Hex Shank

Helix Flute

The shank fits hex impact sockets, so you can use an impact wrench to both ream the hole and install a fastener.

Helix Flute—Prevent clogging when removing excess material with helix flutes. They also leave a smoother finish than straight flutes.

High-Speed Steel—Durable and wear resistant, these are good for general purpose reaming in most materials.

Left-Hand Spiral—These reamers push chips downward as they cut, so they're often used in through holes.

Strong Hold—Magnets on the shank’s end keep these reamers from accidentally falling out of your tool.

					Lg., mm
	Reamer Dia. (A)	Reamer Dia. (B), mm	Material	Hex Shank Size, mm	Flute	Overall	Spiral Direction	Cutting Dia. Tolerance, mm	Performance	For Use On		Each
Helix Flute







				Metric

				20.0000 mm	11.9000	High-Speed Steel	32	114	178	Left Hand	0 to 0.254	Strong Hold	Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel	00000000	000000