2 1/4"-8 Fasteners | McMaster-Carr

These nuts are about 20% stronger than high-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Fastener Strength Grade/Class	Specs. Met	Pkg. Qty.		Pkg.
Steel



	2 1/4"-8	3 1/2"	2 13/64"	ASTM Grade 2H	ASME B18.2.2, ASTM A194	1	90521A050	000000

Steel Socket Head Screws

Partially Threaded

Made of alloy steel, these screws are the standard for high-strength fastening. Use them in high-load applications such as dies, presses, and heavy equipment. The deep, six-point socket keeps the hex key from slipping out and damaging the drive.

Length is measured from under the head.

Black-Oxide Alloy Steel—Typically chosen for their appearance, these screws have a dark, matte coating to create a finished look. They offer minimal corrosion resistance, so they're best for dry environments.

		Head
	Lg.	Dia.	Ht.	Threading	Thread Spacing	Tensile Strength, psi	Specs. Met	Pkg. Qty.		Pkg.
Black-Oxide Alloy Steel







				2 1/4"-8

				6"	3 3/8"	2 1/4"	Partially Threaded	Coarse	170,000	ASTM A574	1	90044A228	0000000


				8"	3 3/8"	2 1/4"	Partially Threaded	Coarse	170,000	ASTM A574	1	90044A229	000000
				10"	3 3/8"	2 1/4"	Partially Threaded	Coarse	170,000	ASTM A574	1	90044A230	000000

Nylon-Insert Locknuts

Versatile yet economical, these are the most commonly used locknuts. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.

High-Strength Steel

Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Yellow-Chromate-Plated Steel—With a more durable finish than clear zinc plating, these nuts are suitable for most wet and outdoor environments. However, they won't hold up to the harsh chemicals that stainless steel can.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	Fastener Strength Grade/Class	Insert Max. Temp., ° F	Pkg. Qty.		Pkg.
Zinc-Yellow-Chromate-Plated Steel



	2 1/4"-8	3 33/64"	2 13/16"	SAE Grade 8	220	1	97135A413	000000


	Steel



			2 1/4"-8	3 33/64"	2 13/16"	SAE Grade 8	220	1	90630A221	00000