Locknuts | McMaster-Carr

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System of Measurement

Thread Size

Nut Type

Material

Locking Type

Finish

Cadmium Yellow-Chromate Plated

Chrome Plated

Corrosion-Resistant Coated

Zinc Yellow-Chromate Plated

Hex Nut Profile

Height

Fastener Strength Grade/Class

Width

Thread Type

Performance

Highly Twist Resistant

Thread Pitch

Thread Spacing

Thread Direction

Specifications Met

Fastener Strength Rating

Screw Size

Washer Material

Thread Fit

Unified Standard Class 2A

Unified Standard Class 2B

Unified Standard Class 3A

Unified Standard Class 3B

DFARS Specialty Metals

RoHS

Compliant with Exemptions

Not Compliant

Insert Maximum Temperature

REACH

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

Yes

Export Control Classification Number (ECCN)

7,658 Products

Locknuts

Nylon-Insert Locking

Nylon-Insert Locknuts

Versatile and economical—the most commonly used locknuts

468 products

Thin-Profile Nylon-Insert Locknuts

About half the height of standard nuts to fit in spaces with low clearance

164 products

Mil. Spec. Nylon-Insert Locknuts

Meet strict U.S. military standards for material and construction

21 products

Mil. Spec. Thin-Profile Nylon-Insert Locknuts

Meet U.S. military standards and are half the height of standard nuts to fit in low-clearance spaces

17 products

Thin-Heavy-Profile Nylon-Insert Locknuts

Fit in low-clearance spaces and handle heavier loads than standard nuts

33 products

Heavy-Profile Nylon-Insert Locknuts

About 10% wider and taller than standard nuts to handle heavier loads

31 products

High-Profile Nylon-Insert Locknuts

Larger gripping area keeps wrenches from slipping off as you tighten

49 products

Nylon-Insert Locknut Assortments

A range of sizes to fasten a variety of parts

2 products

Distorted-Thread Locking

Top-Lock Distorted-Thread Locknuts

Irregularly shaped threads at the top grip screws tighter than a nylon insert

285 products

Center-Lock Distorted-Thread Locknuts

Thread on from either side so there’s no risk of damaging screws

86 products

Left-Hand-Thread Center-Lock Distorted-Thread Locknuts

Secure parts that rotate counterclockwise, such as the propeller on a mixer

5 products

Flex-Top Locking

Flex-Top Locknuts for Heavy Vibration

Stronger hold than nylon-insert and distorted-thread locknuts

87 products

Mil. Spec. Flex-Top Locknuts for Heavy Vibration

Meet strict U.S. military standards for material and construction

18 products

Thin-Profile Flex-Top Locknuts for Heavy Vibration

About two-thirds the height of standard nuts to fit in spaces with low clearance

58 products

Heavy-Profile Flex-Top Locknuts for Heavy Vibration

About 10% wider and taller than standard nuts to handle heavier loads

13 products

Thin-Heavy-Profile Flex-Top Locknuts for Heavy Vibration

Fit in low-clearance spaces and handle heavier loads than standard nuts

9 products

Lock Washer

Locknuts with External-Tooth Lock Washer

Twist into place by hand to save on assembly time

56 products

Locknuts with Spring-Lock Washer

Grip more tightly than external-tooth washers to better resist vibration

21 products

Narrow-Profile Locknuts with External-Tooth Lock Washer

20% narrower than other nuts to fit in cramped spaces

3 products

Assortments of Locknuts with External-Tooth Lock Washer

A range of sizes to fasten a variety of parts

2 products

Thread-Forming Lock

Thread-Forming Locknuts

Form threads into these nuts for a tight fit that won't loosen under vibration

7 products

Spring-Stop Locking

Spring-Stop Locknuts

Withstand heavy vibration similar to distorted-thread nuts and are reusable

10 products

Cotter-Pin Lockable

Locknuts for use with Cotter Pins

Secure rotating parts subjected to mild vibration, such as wheels on carts

98 products

Steel-Insert Locking

Heavy-Profile Steel-Insert Locknuts for Extreme Vibration

About 10% wider and taller than standard nuts to handle heavier loads

19 products

Steel-Insert Locknuts for Extreme Vibration

The most vibration-resistant hold we offer

16 products

Thin-Profile Steel-Insert Locknuts for Extreme Vibration

About two-thirds the height of standard nuts to fit in spaces with low clearance

9 products

Two-Piece-Clamp Locking

Two-Piece-Clamp Locknuts for Extreme Vibration

8 products

Serrated Locking

Serrated Locknuts

Easiest to install but least effective against vibration

7 products

Other Products

Flange Nuts

The flange distributes pressure, so you don't need a washer

399 products

Conduit Locknuts

Secure threaded conduit fittings to knockouts in outlet boxes or enclosures

119 products

Bearing Nuts

Hold bearings, bushings, pulleys, and gears in place on threaded shafts and spindles

412 products

Pipe Locknuts

Thread onto the male end of a pipe fitting so it won't loosen from vibration

119 products

Bearing Lock Washers

Lock bearing nuts in place to prevent loosening due to vibration

103 products

Cap Nuts

Cover and protect threads while adding a finished look; also known as acorn nuts

79 products

Panel Nuts

Extremely thin for tight spots such as electrical panels; also known as dress nuts

117 products

Lock Washers

Resist vibration to prevent fasteners from loosening

1,659 products

Press-Fit Nuts

Push into drilled or punched holes to add threads to thin panels

457 products

Thumb Nuts

Easy to tighten and loosen by hand for making frequent adjustments

8 products

Sealing Nuts

Prevent leaks and block out contaminants with a rubber seal

27 products

Push Nuts

Press onto threads for a light duty hold that’s faster to install than typical nuts

82 products

Tamper-Resistant Nuts

Hard to detach without special tools to prevent unwanted removal

82 products

Split Nuts

Swivel to attach at any point on a threaded rod for quick installation

18 products

Weld Nuts

Weld to metal surfaces to add permanent threads

22 products

End Supports for Ball Screws and Precision Lead Screws

Brace and secure the ends of ball screws and precision lead screws

16 products

Socket Head Screws

With a deeper drive than flat and rounded head screws, these withstand more torque for a tighter hold

437 products

Rivet Nuts

Add threads to thin panels with access from only one side; also known as blind inserts

13 products

Rounded Head Screws

Sit just above the surface for a low-profile finish and hold tighter than flat head screws

792 products

Shoulder Screws

Rotate parts around the cylinder under the head to guide and align them during installation

552 products

Hex Head Screws

Used with nuts to create a stronger joint than flat and rounded screws

143 products

Set Screws

Exert pressure at the tip to hold parts in place, unlike screws that hold material together with threads

336 products

Flat Head Screws

Fit in countersunk holes for a flush finish that won't snag on surrounding parts

162 products