Introduction: DIY Locknuts

Picture of DIY Locknuts

Locknuts are great because they resist loosening from vibrations and torque. They offer an all in one solution to keeping bolts on tight (no lock washers, threadlocker solution). But what if you don't have any locknuts?

This Instructable will illustrate the steps to transforming any nut into a locknut. It is simple, easy and might save you a trip to the hardware store when you are in the middle of a project.

Step 1: Materials

Picture of Materials

You will need these materials:

  • nut(s) that you want to make into locknuts
  • glue- I have tested CA glue and rubber cement with success
  • toothpick or cotton swab

Step 2: Apply Glue to Threads

Picture of Apply Glue to Threads

Start by cleaning off the threads on the nuts to make a quality bonding surface for the glue. Use a toothpick or cotton swab to apply a dab of glue to the nut. The glue should be retained to one half of the nut- if you cover up all of the threads, it will be hard to start a bolt.

Depending on how much holding power you desire, you can either put a small drop on the threads, or cover an entire half of the nut. When you have finished applying the glue, set the nut on end and allow to dry per glue instructions.

Step 3: Use!

Picture of Use!

Once the glue has dried, try threading the nut onto a bolt. You should find that it is very hard to tighten- you will probably need a wrench. If you are still able to hand tighten the nut, add more glue and try again. Anything more than hand tight should be able to resist most vibrations and stray torque.

I noticed when I was experimenting with these homemade lock nuts that it is best if you do not mess with them more than necessary. The more you loosen/tighten the nut, the less locking power it will have. The glue will start to wear off after a couple of times threading.

Thanks for reading this Instructable. Let me know if you have any suggestions or questions.


mrandle (author)2015-08-16

I have been using this stuff recently called bondic. Its like glue but only hardens under uv light. And it hardens instantly! Very handy to keep in the toolbox and fix sloppy threads. You can even start the screw, harden, then use the uv and the threads are now set.

jpierre2 (author)mrandle2015-12-02

Get the bondic kit then lookup "LOCA GLUE" on eBay or Amazon keep the lamp and syringe refill the product in a dim room, afterwards seal the hole you make to refill with something black (nail poslish) to keep light out of your refill. Oh, sunlight cures this stuff fast too. Used LOCA for years used to call it glass glue by 3m also found in windshield repair kits and rearview mirror re-attach kits.

ooohlaa (author)mrandle2015-08-18

i saw it on Amazon and wondered about it ... what projects did you find it useful for, what kind of bonding besides teeth :D I know the taste too.

mrandle (author)ooohlaa2015-08-20

Any light mending really. I keep it in my tool box and tool drawer. I've used it to repair threads before. I've used it to temporarily "solder" wires together or even insulate them after soldering if shrink wrap or electrical tape doesnt't fit. My girlfriend works at an optometrist and they use it all the time for fixing glasses. It's better for building up something rather than gluing really. I dont find it all that sticky and even if it cures on your fingers it just falls off. If you need to stick 2 things together I would use superglue. For everything else, bondic.

ooohlaa (author)mrandle2015-08-20

hmmm sounds like a perfect addition to Superman's tool belt! I bet it would work well on remodeling eyeglasses frames like when it cracks around the lens, or slips on the nose. Gonna get me some for creative solutions kit I always keep handy. Thanx

v-raze (author)mrandle2015-08-17

Some of us are very familiar with that type of adhesive, because it has been in our mouths for years at a time (the adhesive used for braces is a very similar variety, cured by UV). IT TASTES TERRIBLE!

mrandle (author)v-raze2015-08-18

I wish I could get my hands on that stuff my only gripe with bondic is that it is painfully weak unless you use a lot of the stuff. Also haven't tried tasting bondic so I can't say how similar the taste is lol.

stackerjack (author)2015-09-08

Another simple way to make a locknut is to make a sawcut half way through the side of the nut, about 25% from the end.

Then hit the flat side of the nut with a hammer. This closes up the sawcut, and the top part of the thread acts as a locking device.

kioannou (author)2015-08-18

I've been using ca glue for years, but I prefer the liquid version of ca. I tighten the nut, then apply a small drop of ca at the threads. There's also an alternative to locktite by Bison. It's cheaper and safe to use with plastic.

Jerther (author)kioannou2015-08-21

Yeah i thought about locktite too. There's the blue and the red. Blue is alright if you need to loosen/tighten the nut again, but red will lock the thing for good.

kioannou (author)Jerther2015-08-22

This is a useful guide for "safely" replacing a locknut if you don't have a new one to use. (i.e. you decide to fix your garden chairs on a Sunday). CA glue will do its job TEMPORARILY, it's not a permanent solution. I also use CA but only when health and safety is not an issue. I wouldn't use this method to secure my blender's blade, or my bike's brake caliper. Temporary solutions tend to fail catastrophically after a while.

There's also an issue with the fumes. CA glue produces fumes that are toxic and will stain any plastic parts they come in contact with.

There are lots of commercially available thread lockers. Some are fairly cheap, others are quite expensive. There's even thread locker for gas pipes and fire extinguishers. A commonly available thread locker where I live is the Bison metal lock. It costs 6,5 euros for a 10ml bottle and it's good for up to 250-300 M2.5 screws. It's not volatile to plastic, it will unfasten when you want to and it can handle temperatures up to 150 C. I use it in notebook repairs (nobody wants a wobbly screen or a creeking notebook after a month of use) and it does the job perfectly.

Tools and materials have certain purposes. CA glue is a fast curing contact adhesive, not a plastic filament. If a locknut is needed, then a locknut should be used for a safe and long-lasting repair. You shouldn't replace a locknut with a common nut, the same way you shouldn't use a knife to unfasten a screw.

gcai_fwb (author)2015-08-13

Rubber cement is an interesting idea.

I have successfully used plain old nail polish (raid wife/Gf's not used supply) in non-critical applications, as a Loctite replacement - also in comes in pretty colours :).

Nail polish also works well to hold in wood screws that you don't want loosening (eg. IKEA stuff assembly) - would use "Clear" polish if results are potentially visible

_soapy_ (author)gcai_fwb2015-08-22

You can also get a perfect colour match.
Titanium screw in titanium glasses, with colour matched nail polish preventing it coming undone.

Venom8 (author)2015-08-19

Another less expensive way is to distort the nut slightly using a ball peen hammer, Seat the ball of the hammer on the nut and with another hammer tap it just enough to distort a few threads. CAUTION: don't belt the hammers together to hard because they're hardened steel and will chip off like a bullet if hit to hard.

lime3D (author)Venom82015-08-20

Hammers don't break like that. Haven't you ever seen Mythbusters? They busted that myth TWICE.

_soapy_ (author)lime3D2015-08-22

And yet it still happens. Very rare though. More common is mushroomed bits coming off a bolster or similar.

GuyO (author)2015-08-20

E-6000 Adhesive works like a champ. Not too brittle and bonds well to metal.

Gegtor (author)2015-08-20

It will be awesome for drones :D

sadams16 (author)2015-08-19

I have weights that were always clainging and moving so I got some silicone and put a bead on the rod and between each weight and they are nice tight and best of all sillent.

Namirreh (author)2015-08-16

Thanks for the tip. Also in the past I have used a two-step method with silicone.( I work on older motors, All of which are Bow-Tie) Put a "skim/light coat of silicone on the piece you are going to bolt to. Alow to sit for an hour. Apply a "proper" amount of silicone (a bead) to the part. Wait about 45 minutes till it's almost hard at the surface. Install the part.....and tighten till half of the bead starts to spread out. Of course use a pattern of tightening that ensures an even draw of the part to the maiting surface, to keep even. Wait an hour. Torque it home. Finished.
You have found a good part......but....if you are stuck again.....,Now you can work with that handy tube, you are likly to have...before extra gaskets kept on hand. Thanks again for the gasket tip....what engine were you working on....just for my "FYI"

Namirreh (author)2015-08-13

I have used Silicone caulking for this....because it dosen't dry hard and is flexible, it is ideal for cars, mowers..etc. In the seventies I raced stock car at Mosport and my partners uncle ( an old time driver/racer) converted us to "Gasket in a tube", intake manifold, water pump, mechanical fuel pump......pretty well everything but the head gasket came out of a tube....It's cheaper than buying gasket sets every other week !!

amclaussen (author)Namirreh2015-08-16

Yes, it is convenient 99% of the times. I've used many liquid gaskets too... but the other day I was trying (unsuccessfully) to put back the ATF pan on my car, and found it particularly difficult to achieve a tight, drip-free joint. The thing is that the synthetic ATF clings very stubbornly to the automatic gearbox: you can see it still dripping several days after the pan was removed! Therefore, the rear side of the sealing surface (the gearbox to pan sealing surface is slanted) always will get some ATF, even cleaning and cleaning with brake cleaner spray was futile... the ATF quickly got to wet the area, preventing proper adhesion of the silicone. Days later I told my complaints to a very helpful lady that has an Auto Transmission parts store about my pains, she instantly stopped me talking, and brought a new type of auto transmission gasket that is quite thin and seems to have some kind of rubbery compound applied to it, with a wrinkled surface, it is a dark tan color. She told me to AVOID ANY SEALER and just install it as it goes, even without cleaning. It happens that this kind of ATF gasket is not affected by ATF, in fact it makes it work better... End of the problem! Even at close to 6 dollar a piece, this gasket beats the silicone sealer and does not dry in the container if not used within its shelf life (she tells me it actually never expires if stored in a cool dry place, even for years).

Let me tell you that I had tried several different silicone form-in-place gasket sealers, from the standard ones to the very fastest one (it was way TOO fast) and not one of them worked. This pan has 18 bolts and the shape is very irregular, so that applying the silicon sealer takes more than a few seconds. Robotic silicon sealer application at the transmission factory is very convenient for them, but it proved to be less than stellar for car maintenance at home. Amclaussen.

slo5oh (author)2015-08-11

Is there an advantage over using loctite?

rjtumble (author)slo5oh2015-08-13

That's what I was going to ask. Is this the same idea as loctite, but a little cheaper?

icecats (author)rjtumble2015-08-13

The idea is that you put glue on the threads, allow it to dry, and then thread on the bolt. The elasticity of the glue holds tight when a bolt is threaded on.

graydog111 (author)icecats2015-08-15

I always put glue on threads & then put on the nut.

rjtumble (author)icecats2015-08-13

Thanks, your reply made me look up how Loctite works and I found the following PDF. For those interested, page 3 and 4 are the relevant ones to this question.

icecats (author)rjtumble2015-08-13

Very interesting read!

ak08820 (author)rjtumble2015-08-13

The URL is dead

Sir_Sasquatch (author)ak088202015-08-13

The URL works fine on my end.

graydog111 (author)slo5oh2015-08-14

slo5oh asked. "Is there an advantage over using loctite?"

Loctite used to cost $38.00 for a 1 oz bottle (or maybe 2 oz). I don't know what it costs now, but CA on eBay is 5 bucks. Of course, CA is not blue. ;-(

chancefour (author)2015-08-13

"Not good for high heat applications" seems to be mentioned a lot. Is there a substance that is good for high heat?

In the past, I've been doing the nail polish thing and when I wanted a more permanent situation, I took a nail set and struck the end of the bolt to deform the threaded area prohibiting the nut from turning, or just deform the end of the bolt with the ball side of the ball-peen hammer.

graydog111 (author)chancefour2015-08-14

chancefour asked,"Is there a substance that is good for high heat?"

LocTite makes a red thread lock that you will not be able to screw a nut off without heating it red hot with oxy / acetylene torch. Blue thread lock can be removed with wrench.

graydog111 (author)2015-08-14

I have used CA for years on farm machinery. The most amazing experience I had was I had a 24 foot wide shank type plow that had 3 big 5 inch diameter pipes that were drug behind the plow on chains to help flatten out the field. When a chain would break, i would use a bolt with 2 nuts to fasten it back together. The nuts would always loosen and lose off from the vibration. I started using CA and I could tighten the bolt finger tight with CA on threads and it would NEVER loosen. Sorry this is so lengthy, but I am a fanatic about CA. 1 oz bottles are available on eBay for about $5. Search for CA glue.

LindaA12 (author)2015-08-14

Does anyone know if PVC tape will work for any length of time? I've used it, but don't know how well it will hold up.

sb4 (author)2015-08-13

Has anyone tried alum foil in the threads? Just wondering. How about plumber's tape too?

thuzil (author)sb42015-08-13

Aluminum often does not play well when in direct contact with other metals. Look up bimetallic corrosion if you are interested.

DF_Man (author)thuzil2015-08-14


Skysurfer_uk (author)2015-08-14

Nice idea. I tend to find it easier to use a 5" grinder on larger nuts (say M8 & above), using a thin (1mm) disc, cut through from the side about 1/3 the way through. Pinch up in a vice to slightly compress the threads. Done. Thanks for posting!

RJRandall (author)2015-08-14

After the nut is in place, crush it slightly with vise grips. this will upset the thread preventing it backing out on its own but will allow removal with a wrench if needed.

londobali (author)2015-08-13

Good idea.. Thanks for sharing..
I usually just thread the nut into position and then apply some glue on the bolt. Just a little if i intend to loosen it later in the future, or lots if i want to keep it in place as long as possible..
I do this quite often on my motorbike, i'll have a go with your trick next time..

I found that super glue are usually too brittle, hot glue comes off too easy with my way but maybe good in your technique. Most of the time i use rubbery glue like the yellow glue they use in leather business.
Silicon beading glue (aquarium glass glue) might be a good option for inside the nuts..

DoxxRoxx (author)2015-08-13

Thanks for this instructable. I could have used this last week. Oh well, maybe next time.

For those applications where high temperatures are present, try using high-temp RTV silicone. The type used in the automotive industry.

madmedix (author)2015-08-13

Great job. There's a couple of other ideas: I've used LePage's epoxy steel for the same purpose, but you'll need a large air wrench to get it off. Couldn't break it with a 1/2" drive socket and cheater bar! The second (but not as sturdy) was using a lighter to melt the end of a glue stick (the melting glue gun kind) and let it drip onto the nut/bolt once fastened.

TerryN4 (author)2015-08-13

Fingernail polish I have found works well, and also serves as an immediate indications someone else has tampered with the bolt/nut.

StuartB4 (author)2015-08-13

Further up the page someone asked if there is any advantage using things such as fishing line, glue, Hot Glue etc over Loctite. The major advantage would have to be, Loctite can't be used if it can come in contact with plastic, it can eat the plastic away. One of the properties of Loctite is it can migrate or "wick" along the bolt's thread and if the bolt passes through plastic this could be a major problem over time.

The Electrobot (author)2015-08-13

Could it be removed if required in the future?

I always use two bolts and make them tighetened against themselves to lock them in place. I use this method in high vibration conditions. Its not fool proof, but does hold on much better than adding multiple bolts. I have never tried gluing them though.

Microbe (author)The Electrobot2015-08-13

i think you mean two nuts, not two bolts :P

icecats (author)The Electrobot2015-08-13

This could certainly be removed in the future. The hack is meant to keep the nuts from vibrating free, but a couple of leveraged wrenches or possibly some heat would allow for easy removal.

The double nut method works very well. It is nice to know that you have multiple options when it comes to keeping bolts tight!

blackslax (author)2015-08-13

I can understand how this works as I've seen lock nuts that have a strip of plastic that runs across the threads...and they worked great.

One variation on this is what I use at home in lieu of Lock-Tite: old nail polish from the Mrs. It even has a brush for the application!!

Groaker (author)blackslax2015-08-13

There were at least two corporations that made such. One drilled a hole into the screw, then inserted a piece of plastic filament. The other milled a slot along the length of the screw, and used a guillotine to force a strip of plastic into the slot. The one that milled the slot would also use a rolled pin of copper or stainless steel in place of the plastic for high temperature applications.

In either case, the plastic or metal would try to expand to its original shape, and would increase the friction on the opposite threads to keep the screw from coming loose.

A less expensive version was also available which had a similar plastic insert, but they were of lower quality as much of the holding power was the result of the guillotice hitting the threaded portion of the screw, and creating a swage which would also create friction to hold the screw in place.

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