B121 Grinding Bits | McMaster-Carr

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Shank Diameter

Shape

For Use On

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Grit

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Material

Abrasive Material

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Grit Rating

Diameter

Nylon Mesh Grade

For Finish

For Use With

Grinders for Bits and Burs

Head Length

1/2"

Rotation Speed

30,000 rpm to 99,999 rpm

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

DFARS Specialty Metals

Exempt

Export Control Classification Number (ECCN)

EAR99

Maximum Rotation Speed

REACH

Shape Number

RoHS

Form

8 Products

Nylon Mesh Cushioned Sanding Bits

Style B

The abrasive-embedded mesh construction gives you more control over sanding pressure, creating finer and more consistent finishes in small, recessed, and hard-to-reach areas.

1/8" Dia. × 1 1/2" Lg. Shank

Style B

Coarse Grade—Coarse grade is for aggressive deburring and cleaning.

Medium Grade—Medium grade is for deburring and polishing.

Fine Grade—Fine grade is for light blending and finishing.

	Dia.	Lg.	Nylon Mesh Grade	For Finish	Max. Rotation Speed, rpm	Color	Abrasive Material	Abrasive Backing Material	For Use On	For Use With		Each
Style B



	B121	1/2"	1/2"	Coarse	Rough	45,300	Gray	Aluminum Oxide	Nylon Mesh	Steel, Wood	Drills, Grinders for Bits and Burs	4630A152	00000


	B121	1/2"	1/2"	Medium	Smooth	45,300	Gray	Aluminum Oxide	Nylon Mesh	Steel, Wood	Drills, Grinders for Bits and Burs	4630A151	0000
	B121	1/2"	1/2"	Fine	Extra Smooth	45,300	Gray	Silicon Carbide	Nylon Mesh	Steel, Wood	Drills, Grinders for Bits and Burs	4630A153	0000

Rubber-Cushioned Abrasive Grinding Bits for Metals

Style

The abrasive grains in these bits are blended with rubber, which cushions during grinding to produce a smoother surface texture than other bits with similar grits. Bits are also known as mounted points and die grinder bits. Head diameter is measured at the widest point.

Caution: As bit shank is exposed beyond _1/2", maximum safe rpm decreases significantly. Refer to ANSI standard B7.1. Use only accessories that have a greater rpm rating than the maximum speed of the grinder you choose.

Ball

Style

For Steel—Bits for steel are aluminum oxide, which is the most common abrasive used in grinding metal.

For Aluminum, For Brass, and For Bronze—Bits for aluminum, brass, and bronze are silicon carbide, which cuts through soft metals without generating much heat or causing material buildup.

		Head				Abrasive
	Style	Dia.	Lg.	Max. Rotation Speed, rpm	Shape No.	Material	Bond Material	Shank Lg.	Choose a Grit (Surface Texture)		Each
For Steel







				1/4" Diameter Shank

				4	1/2"	1/2"	76,390	B121	Aluminum Oxide	Rubber	1 1/2"	46 (Rough) Brown, 70 (Smooth) Black, 120 (Smooth) Green, 180 (Smooth) Red	4919A326	000000


				For Aluminum, Brass, and Bronze







								1/4" Diameter Shank

								4	1/2"	1/2"	76,390	B121	Silicon Carbide	Rubber	1 1/2"	46 (Rough) Brown, 90 (Smooth) Black, 120 (Smooth) Green, 240 (Extra Smooth) Red	4919A876	00000

Grinding Bits for Metals

Style

Made of aluminum oxide, these bits are well suited for use on most metals and materials that are not heat sensitive.

Bits are also known as mounted points and die grinder bits. Head diameter is measured at the widest point.

Ball

Style

		Head				Abrasive
	Style	Dia.	Lg.	Max. Rotation Speed, rpm	Shape No.	Material	Bond Material	Shank Lg.	Choose a Grit (Surface Texture)	Pkg. Qty.		Pkg.
For Steel, Stainless Steel, and Iron







				1/8" Diameter Shank

				27	1/2"	1/2"	45,370	B121	Aluminum Oxide	Vitrified Clay	1 1/2"	46 (Rough) Blue-Gray, 60 (Rough) Orange, 120 (Smooth) Blue	5	4522A148	000000

Cotton-Laminate Grinding Bits for Metals

Style

Made of cotton fiber layers embedded with aluminum-oxide grains, these bits grind and finish in one step. They’re ideal for light deburring, blending, and finishing metal. These grinding bits remove material more efficiently than rubber-cushioned bits. While grinding, they resist the buildup of aluminum, brass, bronze, and other nonferrous metal. They’re also known as mounted points and die grinder bits. Head diameter is measured at the widest point.

Ball

Style

		Head				Abrasive
	Style	Dia.	Lg.	Max. Rotation Speed, rpm	Shape No.	Material	Bond Material	Shank Lg.	Grit (Surface Texture)		Each
For Steel, Stainless Steel, Aluminum, Brass, Copper, Iron, Nickel, and Titanium







				1/8" Diameter Shank

				2	1/2"	1/2"	45,370	B121	Aluminum Oxide/Cotton Laminate Blend	Rubber	1 1/2"	80 (Smooth) Blue-Gray	4806N351	00000

Grinding Bits for Stainless Steel

Style

Bits are specially formulated to stay cool during grinding, so they won’t mar or discolor stainless steel. They are also known as mounted points and die grinder bits. Head diameter is measured at the widest point.

Ball

Style

		Head				Abrasive
	Style	Dia.	Lg.	Max. Rotation Speed, rpm	Shape No.	Material	Bond Material	Shank Lg.	Grit (Surface Texture)		Each
For Stainless Steel







				1/8" Diameter Shank

				4	1/2"	1/2"	45,370	B121	Aluminum Oxide	Vitrified Ceramic	1 1/2"	80 (Smooth) Pink	44005A51	00000