How to Use Lock Washers

Co-authored by Barry Zakar

Last Updated: October 25, 2022 References

Over time, bolted nuts and other threaded fasteners can loosen up due to friction and joint movement. Lock washers are a type of hardware that, unlike regular washers, can hold those objects in place.^{[1]
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Expert Source

Barry Zakar
Handyman
Expert Interview. 20 August 2020.} When properly applied, lock washers provide a cheap, simple way to keep threaded fasteners steady over a long period of time.

Things You Should Know

Tighten your threaded fastener over the lock washer, making sure the washer is tight against the fastener and other surface.
Unscrew the fastener and pry the lock washer off with a flat screwdriver to remove. If needed, lubricate the washer with WD-40.
Choose a split, tooth, serrated Belleville, or tab washer depending on the type of hold you need.

Method 1

Method 1 of 3:

Assembling a Lock Washer

1
Place the lock washer under the threaded fastener. When used correctly, a lock washer will hold the nut or other threaded fastener in place. To help it accomplish this, put the lock washer on first, below the fastener. If your project calls for other washers or hardware elements, they should go on before the lock washer so that it can hold them in place.
2
Make sure your washer is tight against the fastener and other surface. To operate correctly, your lock washer must press against both the threaded fastener and the other adjacent surface, creating a tight connection. If the connection isn’t tight, press the fastener down until it is. This is particularly important when dealing with lock nuts, which require that that grooves of a toothed washer lock together with the grooves of the nut.

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3
Tighten your threaded fastener. For small, general purpose jobs, tighten your nut or threaded fastener by turning a wrench or ratchet clockwise. Do this until the fastener is firm but can be loosened if necessary. For large or specialty jobs, consult your project manual or nut head markings for a specific torque value, then use a torque wrench to tighten your fastener to the specified amount.^{[2]
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4
Examine your washer to make sure it is operating correctly. Check to see that any teeth on your washer are completely covered by the nut or fastener head. For split washers, make sure that the washer is slightly out of alignment, indicating that it is exerting tension on the threaded fastener. If the washer is not operating correctly, loosen the nut or threaded fastener and fix the washer.^{[3]
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Method 2

Method 2 of 3:

Removing Lock Washers

1
Remove the nut or threaded fastener holding the washer in place. For most nuts and fasteners, you can attach a simple wrench or vise-grip to the object and turn it counter-clockwise. For stuck nuts and threaded fasteners, you may need to use a stronger tool like a pipe wrench, which you can grip onto the fastener and turn like a regular wrench.^{[4]
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2
Pry the lock washer off with a flat screwdriver. If you’re removing a split washer, place the screwdriver head beneath the washer or inside the split and push. If you’re removing a washer with teeth, place your screwdriver head under a tooth and push up, repeating with more teeth if necessary. For other washers, place your screwdriver head below the washer and push up.^{[5]
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- Depending on the amount of pressure the washer is under, it may break when removed.
3
Spray the washer with lubricant if you can’t get it off. If the lock washer won’t budge, spray the area with a penetrating lubricant like WD-40, Royal Purple Max Film, or PB Blaster Penetrating Catalyst. This will loosen up your washer and make it easier to remove.^{[6]
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Expert Source

Barry Zakar
Handyman
Expert Interview. 20 August 2020.} After applying the lubricant, repeat the previous step.^{[7]
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4
Throw away worn out washers. Some lock washers, like serrated Bellevilles, can withstand multiple uses easily. Other washers, like split locks, wear out after 1 or 2 uses. For safety, do not reuse split lock washers or washers that are damaged. If you’re dealing with high-stress joints, do not use old washers at all.^{[8]
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Method 3

Method 3 of 3:

Picking a Lock Washer

1
Use a split lock washer for small jobs. A split lock washer, also known as a helical spring washer, is the most common form of lock washer. Instead of using grooves, it operates more like a spring, holding the threaded fastener in place with friction. Use a split lock on a small, low-intensity job, since bigger loads will flatten the washer and make it useless.^{[9]
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2
Use tooth lock washers for extra force. With their jagged edges, tooth lock washers hold the nut or threaded fastener in place with a significant amount of force. They come in two forms: internal tooth and external tooth. Internal tooth washers work best on small screws or screws used in electrical grounding, while external tooth washers work best on large screws.^{[10]
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- Tooth lock washers work well with aluminum and soft plastic surfaces.
3
Choose a serrated Belleville washer for extremely tense loads. Serrated Belleville washers are conical pieces of hardware with grooves on the surface. They are used to distribute tension at a joint, and though they won’t provide as much locking force as other lock washers, they can be useful when dealing with extremely large, tense loads.^{[11]
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4
Pick a tab washer for harsh environments. If your nut or threaded fastener needs to withstand intense climates, go with a tab washer. These pieces of hardware have one or more tabs that, when bent against the nut or fastener head, hold it in place.^{[12]
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Expert Q&A

Question

How do lock washers work?

Barry Zakar
Handyman
Barry Zakar is a professional handyman and the founder of Little Red Truck Home Services based in the San Francisco Bay Area. With over ten years of experience, Barry specializes in a variety of carpentry projects. He is skilled at constructing decks, railings, fences, gates, and various pieces of furniture. Barry also holds his MBA from John F. Kennedy University.

Barry Zakar

Handyman

Expert Answer

Lock washers look like any other washer except that the slit in it is raised slightly higher on one side. Because of this raised side, it's better at keeing tension on the screws.