M50 Nuts | McMaster-Carr

With a nylon insert that grips your threaded shaft or spindle without damaging its threads, these locknuts—also called shaft nuts—hold bearings, bushings, gears, and pulleys prone to vibration tightly in place. They come as one piece, so you can easily clamp them onto your shaft or spindle. But, since they aren’t made entirely of metal, they don’t stand up to heat as well as all-metal locknuts. Slots in their sides mean you can tighten and loosen them with a spanner wrench or spanner socket. Their face is also chamfered to help keep the size and weight of your assembly at a minimum. All meet international standards for bearing locknut dimensions.

Zinc-Plated Carbon Steel—Zinc-plated carbon steel locknuts resist rusting from some moisture, but you shouldn’t use them with salt water or chemicals. They are strong and resist wear, though they don’t stand up to corrosion as well as 303 stainless steel locknuts.

Carbon Steel—All carbon steel locknuts are strong and resist wear, though they don’t stand up to corrosion as well as 303 stainless steel locknuts.

303 Stainless Steel—303 stainless steel locknuts resist corrosion better than carbon steel locknuts but aren’t as strong. They withstand washdowns and chemicals.

Thread Spacing—When choosing your thread spacing, consider the precision of your application. The finer the threads, the more control you have when making adjustments.

	Locknuts												Sockets
	Thread						Carbon Steel		Zinc-Plated Carbon Steel		303 Stainless Steel
	Size	Spacing	OD, mm	Wd., mm	Insert Max. Temp., ° F	Specs. Met		Each		Each		Each		Each
Chamfered Face



		M50 × 1.5 mm	Extra Fine	68	13	210	—	———	0	3552N45	000000	———	0	———	0


		M50 × 1.5 mm	Extra Fine	70	13	160	ISO 2982-2	6343K41	000000	———	0	6343K66	000000	5510N158	0000000

Bearing Nuts

Carbon Steel

Chamfered Face

Carbon Steel

Stepped Face

Often paired with spring lock washers to strengthen their hold, these bearing nuts—also known as shaft nuts—keep vibration from shifting bearings, bushings, pulleys, and gears on your threaded shaft or spindle. They have slotted sides, so you can tighten and loosen them with a spanner wrench or spanner socket.

Carbon Steel—Carbon steel bearing nuts are strong and resist wear.

Chamfered Face—Chamfered-face bearing nuts weigh less and produce less heat than stepped-face nuts.

Stepped Face—Use stepped-face bearing nuts with DIN 462 spring lock washers. You can also use them in pairs or with other bearing nuts. For the nut closer to the bearing, position the stepped face towards the bearing. All meet DIN standards for bearing lockout dimensions.

ISO 2982— Some chamfered-face bearing nuts meet ISO 2982 (formerly DIN 981), an international standard for bearing locknut dimensions. Their sizes correspond to SKF KM series. Use them with DIN 5406 spring lock washers.

Thread Spacing—When choosing your thread spacing, consider the precision of your application. The finer the threads, the more control you have when making adjustments.

	Nuts								Bearing Lock Washers		Sockets
	Thread
	Size	Spacing	OD, mm	Wd., mm	Specs. Met	For Lock Washer Specs. Met		Each		Each		Each
Carbon Steel







				Chamfered Face

				M50 × 1.5 mm	Extra Fine	70	11	DIN 981, ISO 2982	DIN 5406	3554N22	000000	90391A122	00000	5510N186	0000000




						Stepped Face

						M50 × 1.5 mm	Extra Fine	75	13	DIN 1804	DIN 462	3564N28	00000	90407A133	0000	———	0

Conduit Locknuts

Secure threaded conduit fittings to knockouts. These locknuts keep fittings from shifting, so connections stay stable and wiring is protected inside electrical boxes or enclosures.

For Metal and Plastic Fittings

304 Stainless Steel—The choice for wet and outdoor environments.

Nickel-Plated Brass—The plating enhances the corrosion resistance of brass, adding a durable protective finish.

	Each
Metric Thread







	304 Stainless Steel

	M50	—	7513K139	000000




			Nickel-Plated Brass

			M50	EN 60204	9147T23	00000

For Plastic Fittings

Nylon—Lightweight and chemical resistant, these fittings won't corrode.


Metric Thread







	Nylon

	M50	7877N115	000000

Spanner Sockets


Socket Shown With Wrench (Sold Separately)

4-Pin

For easy tightening and loosening, these sockets have pins that grip the slotted sides on bearing nuts. These sockets require less clearance around bearings than standard hook spanner wrenches, so they’re good in tight spaces. Use them with a square-drive wrench handle or a ratchet wrench; they’re not for use with impact wrenches.

							Clearance Dp., mm
	Drive Size, mm	Overall Lg., mm	OD, mm	For Nut Thread Size	For Bearing Nut Specs. Met	For Nut Dia., mm	Nut	Bolt	Material		Each
4-Pin Socket







				1/2" Square Drive

				70	90	86	M50	ISO 2982-2	70	—	65	Steel	5510N158	0000000




						3/4" Square Drive

						70	90	78.5	M50	DIN 981, ISO 2982	70	13.8	62	Steel	5510N186	000000

Thin-Profile Bearing Nuts

Used in pairs or with another bearing nut, these thin-profile nuts—often called shaft nuts—hold bearings, bushings, pulleys, and gears in place on your threaded shaft or spindle. Threading two nuts tightly against each other makes it harder for vibration to loosen your assembly than if you used only one nut. For the nut closer to the bearing, position the stepped face towards the bearing. These thin-profile nuts have holes on the side, so you can tighten and loosen them with a pin spanner wrench. All meet DIN 1816, an international standard for bearing locknut dimensions.

Carbon Steel—Carbon steel bearing nuts are strong and resist wear.

Thread Spacing—When choosing your thread spacing, consider the precision of your application. The finer the threads, the more control you have when making adjustments.

	Thread
	Size	Spacing	OD, mm	Wd., mm	Specs. Met		Each
Carbon Steel







				Stepped Face

				M50 × 1.5 mm	Extra Fine	75	13	DIN 1816	3549N28	000000

Fast-Travel Ball Screws and Nuts


	Ball Nuts, Externally Threaded Nut, Style C

Multiple thread channels (also known as thread starts) create faster linear travel than ball screws with a single thread start. Internal ball bearings provide smooth low-friction travel in applications that require high speeds, accurate positioning, and repeatable movement. To ensure compatibility, select components that have the same thread size and number of thread starts. Ball nuts are furnished with a tube to keep ball bearings in place. Do not remove the tube until you are ready to install the nuts onto the screws.

Externally Threaded Ball Nuts—Right-Hand Threaded

Image of Product. Front orientation. Contains Annotated. Ball Screws and Nuts. Fast-Travel Ball Screws and Nuts, Ball Nuts, Externally Threaded Nut, Style C.

Style C

Carbon Steel—Carbon steel ball screws and nuts are case hardened, so they resist wear better than standard carbon steel. However, they are less corrosion resistant than black-oxide alloy steel screws and nuts.

Travel Distance per Turn—Travel distance per turn, also known as screw lead, is the distance a ball nut moves with one revolution of the ball screw.

	Thread Size	Lg., mm	Dia., mm	No. of Thread Starts	Travel Distance per Turn, mm	External Thread Size	Hardness	Dynamic Thrust Load Cap., lb.	Max. Backlash, mm	Temp. Range, ° F		Each
Carbon Steel



	C	M32	90	53	4	32	M50	Rockwell C56	3,700	0.03	32 to 150	4566N303	0000000