# Lock Washers a Waste of Time?



## Chips O'Toole (Dec 2, 2019)

When I build projects, I use lock washers to prevent nuts from coming off. Today I read that they do not actually work. I am wondering if anyone here has heard about this.

A site called Bolt Science says experiments have shown that lock washers are useless, and that you're better off using Loctite or just tightening things securely.

Now I feel like I have to go out and remove a whole bunch of lock washers.

Maybe blue Loctite should be the default option instead of something for occasional use.

It always amazes me to find out engineers are completely wrong about simple things like this. If they're wrong about this, what else are they wrong about?

Page from Bolt Science


----------



## Latinrascalrg1 (Dec 2, 2019)

I file that into, you could find "evidence" to "prove" whatever result you actively seek out category and would choose personal experience over published article..... personally I feel lock washers, when used correctly, do a good job for what they were designed.  My $0.02 worth.


----------



## ddillman (Dec 2, 2019)

I believe locktite is better, but I think lockwashers do work. I don't think manufacturers would waste the time and money to use them if they didn't do something


----------



## Winegrower (Dec 2, 2019)

I would have to see the experiments they did.   My understanding is that lock washers provide some force that prevents loosening under vibration.  This needs more info.


----------



## RobertB (Dec 2, 2019)

I've never really found a nut with a lock washer under it any harder to break loose than one without. To me where they offer a benefit is in keeping the fastener from rapidly coming completely off of the bolt. With no washer, once the nut breaks free it can rapidly spin off of the bolt. With a washer it will slow this down until the range of the washer is reached. This may give you time to notice something is loose before it falls apart completely.


----------



## Winegrower (Dec 2, 2019)

I missed the OP link.   Interesting.   I don’t know what i don’t know.   I do know that in aviation, where it’s pretty important parts don’t fall off, lock washers are not used.   Self-locking nuts, cotter keys and safety wire are pretty standard.


----------



## JPMacG (Dec 2, 2019)

And for spaceflight hardware, split lockwashers are forbidden.  They can fracture, creating FOD, which may cause big trouble.   It is lock nuts or staking, or both.

I think saying that lockwashers are ineffective is too broad a generalization.  I believe that they probably do work well for some applications.


----------



## royesses (Dec 2, 2019)

One of the first training lessons we had at Caterpillar is on bolts, washers and torque. Cat does not use lock washers because they cause loose bolts. They use only hardened flat washers. Lock washers work for very minor assemblies that don't get much load or stress and are not life critical. They can cause loosening of bolts/nuts in vibrating environments. Cat uses lock tabs and lock nuts and sometimes prevailing torque nuts. They also use loctite.

Roy


----------



## Cooter Brown (Dec 2, 2019)

Just buy a torque wrench, lock washers are garbage and every thing I buy that comes with them gets taken apart and I remove them all....


----------



## CluelessNewB (Dec 2, 2019)

Personally I use lock washers, nylocks or loctite.  The only things I can think of that have lost screws are cheap products from you know where that didn't have anything.


----------



## benmychree (Dec 2, 2019)

Take a lesson from Henry Ford on the Model T; they used lockwashers on the engine pan, and also used cotter pins along with them, the lockwashers maintained tension against the cork gaskets, and the cotter pins prevented things from falling apart when that tension ceased.  Or, possibly credit the Dodge Brothers, who manufactured all the early Ford components up to 1914.


----------



## BtoVin83 (Dec 2, 2019)

My dad always said that if the faces are flat lock washers aren't needed. On my sawmill the bolts would loosen on the drive wheel bearing flange mounts. Lock washers cured it.


----------



## f350ca (Dec 2, 2019)

Just my thoughts, for what they're worth. 
When using longish bolts or studs, the stretch in a properly torqued fastener will keep the nut tight. When fastening thin material where the body of the fastener is short a lock washer will help maintain the tension that holds the nut from turning. 
A lot of automotive or industrial equipment that is subjected to cyclic loading and vibration utilize nuts with a wide flange to help resist rotation (as well as distribute the load). The lock washer helps prevent rotation on a standard nut.

Greg


----------



## GL (Dec 2, 2019)

Except for maybe Nordloc's, lock washers are poor keepers in critical situations.  Split locks are really bad, as mentioned before, they break out from under the fastener (or can, especially if reused).  The "spring" in the system should be the bolt.  If the bolt isn't long enough to be the spring, then another method (mechanical like safety wire, cotter pins, lock nuts (all metal top locks for larger than 5/16, nylocks for under), etc. or chemical like Loctite) is a better answer.  You don't see lock washers on the rotating parts or head bolts of an engine.  Pan bolts, while important to keep the juice in, or anything across a gasketed (I.e. movable) surface doesn't classify as a critical joint, so maybe split locks function (my experience is the torque spec is so you don't split the gasket, not to keep the bolt tight). There may be some marketing that promotes split locks as an enhancement, if for no other reason than the function is intuitively obvious.  But blood letting had proponents at one time also.  We could go into the reasons that torque is a craptastic method of measuring clamp load, which is really what we are trying to get to, in an effort to make enough friction to keep it all together but that's a whole 'nother discussion.  And yes, I am an engineer - don't pretend to know everything, but I didn't learn everything out of a book either (most of the engineers I work with can't spell lathe, fewer actually use wrenches to work on anything, and I cuss engineers more than most people do because of it.)  We build primarily off-highway trucks with no rear suspension, lock washers are not used - anymore.


----------



## MontanaLon (Dec 2, 2019)

Winegrower said:


> I missed the OP link.   Interesting.   I don’t know what i don’t know.   I do know that in aviation, where it’s pretty important parts don’t fall off, lock washers are not used.   Self-locking nuts, cotter keys and safety wire are pretty standard.


But for safety wire and speed tape, planes would never stay together.


----------



## higgite (Dec 2, 2019)

According to ASME, helical spring lock washers, or split ring washers if you prefer, aren’t intended to prevent loosening. They are intended to compensate for loosening within their range of capability. ASME publishes a standard for washers, including lock washers. The user is responsible for picking the proper washer for their particular application. Choose wisely.

Tom


----------



## T Bredehoft (Dec 2, 2019)

I don't have a dog in this hunt. Having said that, in probably 68 years of turning wrenches I don't recall ever seeing a nut with a loose lock washer under it. 
Yes, I do occasionally use Locktite, but only if I don't plan on removing the nut.


----------



## Winegrower (Dec 2, 2019)

Most interesting.  I appreciate the anecdotal information about different application areas.   I think I might do some things differently here on.


----------



## rock_breaker (Dec 3, 2019)

The above discussion is very interesting and I notice no comment about the spurs on the outer corners of some lock washers, especially those from old time  manufacturers. Being ignorant of the technical aspects I thought those spurs were there to gouge the nut and parent metal in a short distance of rotation and restrict further loosening. As for small diameter lock washers sold these days many are as smooth as baby bottoms. No doubt in critical fastener surfaces and mating material surfaces should be parallel and I would use some locktite also.
Have a good day
Ray


----------



## whitmore (Dec 3, 2019)

Chips O'Toole said:


> When I build projects, I use lock washers to prevent nuts from coming off. Today I read that they do not actually work.



The best use of star-type lock washers is in electrical connection, especially through paint.   I've seen them
fail badly, though,  in mechanical securing of parts.   It might be that a heavy torque on the fastener
flattens the lock washer (but for grounding, I just counted turns after getting finger-tight, to get through the paint).


----------



## tghsmith (Dec 3, 2019)

being a BMW motorcycle mechanic many years back, spring wave washers are used where steel bolts are holding alloy parts together,, correct torque values applied (gutentite) thermal cycling, different expansion and all that,, specific drive train bolts were one time use, (stretch bolts) the u-joint to gearbox flange (steel to steel) went through changes as time progressed,, originally split hardened lockwashers, then changed to thick wave washers, then to single use bolts, no washers,installed on clean parts with loctite..  on later bikes some specific bolts came pre-locktited,, heat was required for removal,, the new bolt had a locktite coating on part of the threads, friction activated(once started the bolt was cranked down without stopping,)


----------



## matthewsx (Dec 3, 2019)

Read this:





__





						www.CarrollSmith.com -- NUTS, BOLTS, FASTENERS, and PLUMBING HANDBOOK
					





					www.carrollsmith.com
				




Yes, lock washers are no more effective than a plain washer on a properly torqued fastener. I don't know that I would run around removing them where present but if you are concerned do buy a torque wrench and consult a torque table to get things tightened properly. Loctite or Nylock nuts wherever things need to stay together, safety wire if lives depend on it.

Cheers,

John


----------



## Downunder Bob (Dec 3, 2019)

On a large marine diesel engine all critical bolts and nuts will have some form of positive locking of the fastener. A split pin with a castellated nut is one popular method. Tab washers are popular with some engine makers, as is wire tying. You will almost never see lock washers used in any critical situation.


----------



## RJSakowski (Dec 3, 2019)

rock_breaker said:


> The above discussion is very interesting and I notice no comment about the spurs on the outer corners of some lock washers, especially those from old time  manufacturers. Being ignorant of the technical aspects I thought those spurs were there to gouge the nut and parent metal in a short distance of rotation and restrict further loosening. As for small diameter lock washers sold these days many are as smooth as baby bottoms. No doubt in critical fastener surfaces and mating material surfaces should be parallel and I would use some locktite also.
> Have a good day
> Ray


I have been been turning wrenches for more sixty years on things from electronic equipment to farm implements.   On removing nuts used over lock washers, I have observed that the washer will bite into the bottom of the nut, resisting loosening.

I use a number of methods of locking, depending on the situation.  On electronic equipment, I used a drop of cyanoacrylate adhesive applied under the nut just prior to final tightening.  The adhesive would wick under the nut and into the threads.  The best way to remove the fastener was to over tighten snap the fastener, then replace the fastener.

Double nutting is another method that I frequently use.  I can't recall that it has ever failed me.  There was a discussion a while back on this forum regarding the proper use of the jam nut.  Like toilet paper, the camp is divided on over vs. under. Nyloc nuts also work well.

My outboard props use a tabbed washer and it is used in other situations where the nut isn't torqued down with success. I haven't lost a prop yet.  Also, castellated nuts with cotter pins are effective. The spindle nuts on automotive vehicles attest to that.  For fasteners not intended to be removed, staking proves effective.

One method that seems sure fire though, is rust.  I have had far more experience with rusty fasteners where I had to cut them off or break the fastener than I care to think about.


----------



## MrWhoopee (Dec 3, 2019)

On a VW bus (the real ones, thru '67), the front wheel bearings are retained with nut, lock-nut and keyed retaining tab washer between. Rear brake drums are retained with castellated nut torqued to exactly 280 ft. lbs. (6 ft. cheater on 3/4 breaker bar, then jump on it) and cotter key (split pin downunder). 

In general, metric stuff seems to use wavy washers instead of split.


----------



## John281 (Dec 3, 2019)

At work, we use fasteners that have a small patch of locking material encapsulated in tiny microspheres.  The patch is dry to the touch until it's installed and the microspheres rupture.  These are generally single-use fasteners.  (NDIndustries.com)  We make electronics for aerospace where we don't use lock washers either due to the risk of fracture and associated FOD as others noted.

At home, I have found that the clear "Shoe Goo" works well for high vibration applications such as lawn mowers, snowmobiles, and motorcycles.  In reality, it's probably not strong enough to keep a fastener from loosening but it's firm enough to keep a fastener from falling off completely but easy enough to loosen when needed.


----------



## MrWhoopee (Dec 3, 2019)

John281 said:


> At home, I have found that the clear "Shoe Goo" works well for high vibration applications such as lawn mowers, snowmobiles, and motorcycles.  In reality, it's probably not strong enough to keep a fastener from loosening but it's firm enough to keep a fastener from falling off completely but easy enough to loosen when needed.



Ah, yet another use for Shoe Goo. Since getting it to glue the sole back on my Tevas, I've used it to splice the serpentine belt on my Heavy 10 and have been very impressed with its tenacity.


----------



## pontiac428 (Dec 3, 2019)

On track vehicles in the Army, lock washers are used for mounting non-critical vibrating stuff like lamp housings.  On the drivetrain and turret's critical components, lock nuts are the rule.  Internal parts like transmissions get lacing wire.  The torque wrench is your friend.


----------



## BGHansen (Dec 3, 2019)

I was taught that torque is how clamp load is obtained.  The bolts is stretched into tension which maintains the clamp load, basically it's stretched into a spring.  What holds the joint together is friction between the nut/bolt head and the mating surface.  If either rotate (lefty loosie), then some of the clamp load is lost.  Loctite, nylock nuts and I would imagine star-washers increase the friction so the joint will be less likely to loosen.

Key to achieving clamp load is some distance between the head of the bolt and the nut.  Tighten two pieces of sheet metal together with a 1/4"-20 and you maybe get one thread of stretch and little clamp load.  Makes sense that a split lock washer would help put the bolt into some tension and help with the clamp load when bolting up thin materials.  Don't know how much friction (if any) it adds to keep the nut from turning.

Bruce


----------



## mcostello (Dec 3, 2019)

My Eye Doctoruses a drop of clear nail polish on the top of eye glasses screws to prevent loosening, easy to remove.


----------



## Chips O'Toole (Dec 3, 2019)

One of the nice things about blue Loctite is that it in addition to reducing loosening, it provides something of a barrier between fastener surfaces. I don't know if it provides significant protection from rust and galling, but it probably does.


----------



## Mitch Alsup (Dec 3, 2019)

BGHansen said:


> I was taught that torque is how clamp load is obtained.  The bolts is stretched into tension which maintains the clamp load, basically it's stretched into a spring.  What holds the joint together is friction between the nut/bolt head and the mating surface.  If either rotate (lefty loosie), then some of the clamp load is lost.  Loctite, nylock nuts and I would imagine star-washers increase the friction so the joint will be less likely to loosen.
> 
> Key to achieving clamp load is some distance between the head of the bolt and the nut.  Tighten two pieces of sheet metal together with a 1/4"-20 and you maybe get one thread of stretch and little clamp load.  Makes sense that a split lock washer would help put the bolt into some tension and help with the clamp load when bolting up thin materials.  Don't know how much friction (if any) it adds to keep the nut from turning.
> 
> Bruce



The trick with using torque to hold a bolt and nut together is: that the proper torque clamps the things together in such a way that under no situation (of vitration or change in load), does the threaded member end up with zero tension and loses its clamping force.


----------



## Z2V (Dec 3, 2019)

MrWhoopee said:


> On a VW bus (the real ones, thru '67), the front wheel bearings are retained with nut, lock-nut and keyed retaining tab washer between. Rear brake drums are retained with castellated nut torqued to exactly 280 ft. lbs. (6 ft. cheater on 3/4 breaker bar, then jump on it) and cotter key (split pin downunder).
> 
> In general, metric stuff seems to use wavy washers instead of split.



This would be a Starrett cheater and breaker bar, and a 140# jump with two feet to achieve 280 ft. lbs.? That’s how we do it!!


----------



## BtoVin83 (Dec 3, 2019)

Put a pipe wrench on the nut and drive around the yard.


----------



## Illinoyance (Dec 3, 2019)

The Bolt Science data is based on testing with a Junker machine. It created alternating shear load in the test joint.  It is the clearance between the bolt and nut that allows relative motion between them leading to loosening.  The reason Loctite is so effective is that it fills the gap between the nut and bolt therefore preventing relative motion.  

If sufficient clamping force is applied to the joint to prevent sliding of the bolted members there can be no relative motion between the nut and bolt.  In structural engineering that is called a slip critical connection.  All the shear load between the members is transmitted by friction.  The shear force on the bolts is assumed to be zero.


----------



## BGHansen (Dec 3, 2019)

mcostello said:


> My Eye Doctoruses a drop of clear nail polish on the top of eye glasses screws to prevent loosening, easy to remove.


I used that when building Erector set models that would be transported.  Poor man's Loctite, never had a screw back off.

Bruce


----------



## MrWhoopee (Dec 3, 2019)

BtoVin83 said:


> Put a pipe wrench on the nut and drive around the yard.



I've actually had to put the socket, breaker bar and cheater on, then back up to try to break the nut loose. Raised the back end about 18 in. off the ground.


----------



## westerner (Dec 3, 2019)

My old friend Reed grew up in this field. His Dad was fond of saying "Stripped threads is worth TWO lockwashers!"

The very first shop I ever drew a paycheck from used alot of Permatex #2. I use it to this day.  But we did not work on airplanes


----------



## Superburban (Dec 3, 2019)

What about serrated flange nuts and washers? They are what I go to for frame and suspension work, have not had any loose ones yet.


----------

