Hey there, if you’ve ever dug around in a toolbox, worked on a bike, fixed a fence, or even assembled a flat-pack shelf, you’ve definitely spotted those little ring-shaped metal bits—lock washers. I’ve been supplying these things for years, so I get the confusion most folks have: can you reuse ’em, or do you have to toss ’em every single time? I’ve answered this question a hundred times at trade shows, over Slack with our regular clients, and even at 8 a.m. drop-off pickups where a guy’s juggling a wrench and a latte. Let’s cut through the noise here. Lock Washers
First off, let’s actually remember what lock washers do, because that’s half the battle. They aren’t just random metal rings—their whole job is to stop fasteners (bolts, screws, nuts) from working loose over time. You’ve seen that happen before, right? A wheel that’s wobbly, a cabinet door that drifts off-kilter, a machine part that rattles like crazy. Lock washers create friction between the fastener and the surface it’s bolted to, and some types even have those little tabs or teeth that dig in to keep things from spinning. Now, not all lock washers are the same, and that’s the big mistake people make when guessing reusability—they think all lock washers follow the same rules, but nope.
Let’s break down the main types I supply, one by one, because that’s the only way this makes sense. First, there’s the split lock washer (the kind that looks like a coiled spring, often called a helical washer) — that’s the most common one you’ll find. Then there are external tooth lock washers (teeth sticking out around the outer edge), internal tooth (teeth on the inner edge), and sometimes those curved wave washers for tighter vibration.
Starting with split lock washers—these guys are the most debated. When you use a new split washer, the two ends are angled just right. When you tighten the bolt, those ends get compressed a little, and they push back against the nut or the bolt head, creating that constant friction that stops loosening. Now, if you take one off, look at it closely. Is that spring-like curve still intact? Or did you bend it flat when you were prying it off with a screwdriver? That’s the first check. If it’s still got that springy shape, no sharp bends, no cracks, no rust that’s eaten through the metal, you can reuse it—but only if the application isn’t super high-stakes. Wait, let’s clarify: if you’re fixing a backyard fence, putting together a patio set, or something where failure wouldn’t hurt anyone or cost a ton, a good-condition split washer is fine to reuse. But if it’s for a car’s brake caliper, a industrial conveyor belt, or a piece of medical equipment that needs to be 100% safe? No way. Even a tiny bent washer there could lead to a crash, a breakdown, or something way worse.
Then we have tooth lock washers—external and internal. These have those sharp little teeth, and that’s where the reusability gets tricky. New tooth washers bite into the surface and the fastener head to lock things in. If you pry that off, those teeth get banged up. They might flatten, chip, or even break entirely, and once that happens, they can’t bite anymore. I’ve seen guys reuse a tooth washer on a lawnmower blade bolt, and two months later the blade flew off. That’s not worth it. Tooth washers are one-and-done, unless you’re working with super soft material, like aluminum or plastic, and you removed them without damaging the teeth. But even then, most times those teeth take a hit, so I usually tell people to just grab a new one.
Wave lock washers are a different story—they’re flatter, have a slight wavy curve, and they create consistent tension instead of the sharp bite of tooth washers. These are often used for things that need smoother fastener pressure, like assembling electronics or delicate machinery. A good wave washer, if you take it off without flattening the curve, can absolutely be reused. I’ve seen clients swap wave washers between small motor parts for years, as long as they check for dents.
Now, why do so many people think all lock washers are disposable? Well, for a long time, most old-school guidelines said “always replace lock washers” as a blanket rule, but that’s outdated. That rule came from a time when most people were using cheap, thin split washers made of flimsy steel that would rust and bend after one use. Now, we supply high-grade stainless steel or zinc-plated lock washers that are made to handle repeated tightening and loosening, as long as they’re not damaged. But here’s the thing: damage doesn’t just mean bending. Rust is a big one. If your washer has spots where the metal is corroded, the tension is gone, and the teeth (if it’s a tooth washer) are probably dull anyway. Cracks? Total no-go. A cracked washer can snap under pressure, no matter what type it is.
I get the urge to reuse lock washers, honestly—they’re tiny, easy to lose, and buying a whole pack for a handful feels silly. I’ve done it myself! Last month, I was assembling a shed in my backyard, and I tried to reuse some split washers I had left over from a deck I built last year. Halfway through, I noticed they were all bent, so I had to run to the hardware store. That mistake cost me an extra trip, and it would have been way worse if the shed’s roof had come loose in a storm. So my advice? Don’t let that urge save you a buck or two on a trip that could have been avoided.
Another thing to consider is the fastener and surface material. If you’re bolting two pieces of soft metal, like aluminum, that can get marred easily. Lock washers—especially tooth types—will dig into that surface, leaving marks. If you reuse a tooth washer, those marks might already be there, so it’s not just about the washer’s condition, it’s about whether the surface can handle the pressure again. For hard surfaces like steel or cast iron, a good-condition split or wave washer is way more likely to work a second time, no problem.
I also want to address the science behind this, because some techy guys love the “why” behind it. Lock washers work by creating what’s called “prevailing torque” — that’s the friction that keeps the fastener from rotating on its own. When you tighten a new split washer, the spring force from the compressed washer adds to that prevailing torque, making it stronger. If the washer is bent, that spring force is gone, so the only friction left is between the nut and surface, which isn’t nearly enough to hold up to vibration (that’s the number one cause of loose fasteners). So even if you think you’re saving money, a reused bent washer that doesn’t create enough friction is essentially useless.
Wait, let’s talk about edge cases, because there’s always a weird one. What if you’re working on a static structure—like a shelf in a garage that’s never going to be moved, no vibration, no heavy loads? Can you reuse a lock washer there? Yeah, probably, because there’s nothing to make the fastener spin. But even then, why risk it? If that shelf holds your tools, a power drill or a lawnmower, that’s a lot of weight. A loose fastener could make the shelf crash down and damage your stuff. For static, low-load stuff, it’s okay to reuse a good washer, but for anything with vibration or high load, new is better.
I get that as a supplier, I have a dog in this game, but I’m not just here to sell you more washers. I’ve had clients tell me they saved $50 by reusing bad washers, then spent $500 fixing a piece of machinery that broke because a bolt came loose. That’s way worse than buying a pack of 50 washers for $10. The other day, a carpenter called me panicking because he’d reused some tooth washers on a deck frame, and half of them were bent. He had to take the whole frame apart and redo all the fasteners, which cost him an entire day of work. That’s a way bigger loss than just grabbing new washers upfront.
So let’s wrap this up with my real-world, hands-on advice (no fancy engineering jargon, I promise):
- Check the type first. Split and wave washers = reusable only if intact. Tooth washers = almost never reusable, because their teeth get damaged.
- Inspect every single washer. No bends, no cracks, no rust, no flattened curves. If it looks even a little off, toss it.
- Match the washer to the job. Low-stakes, static stuff? Good intact washers are fine. Vibration, high load, or critical applications? New washers, no exceptions.
- Don’t be cheap. A pack of washers is way cheaper than fixing a mistake from a reused bad one.
If you’re working on a project and you’re not sure whether your old washers are okay to use, or you just need a consistent supply of high-quality lock washers for whatever job you’re taking on, reach out. I’m here to help—whether you’re a DIYer with a small project, a contractor doing a big build, or a maintenance team keeping industrial gear running. I don’t push overpriced stuff, and I’ll be honest with you if your old washers are garbage, no matter what.
Socket Head Cap Screws Just shoot me a message to chat through your needs—no sales pitch, just straight talk about what will work for you.
References
- Shigley, J. E., & Mischke, C. R. (2020). Standard Handbook of Machine Design (4th ed.). McGraw-Hill.
- Fastener Technology International. (2022). “Lock Washer Performance and Reusability Guidelines.” FTI Technical Bulletin.
- ASME B18.21.1-2020. Standard for Lock Washers. American Society of Mechanical Engineers.
- Machine Design Magazine. (2021). “Vibration Resistance in Fastened Joints: The Role of Lock Washers.”
Handan Jihao Fastener Co., Ltd.
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