Locking nuts without loctite

[Tiger]

I saw a guy who had trouble with a nut on his wood lathe (coming loose from vibration) fix this by giving the bolt the nut was on a careful whack with a hammer. I have tried this technique over the years but can't quite replicate it. What is the actual technique to be used, I do have loctite but I want to be able to undo the nut eventually without having to apply heat to loosen the loctite.

[Gra]

Only thing I can think of would be compress the threads, so it slightly changes the pitch... Dunno how else it would work..

Try a good dose of silastic on the threads usually stops things moving and easy to peel off when done



Or you could always fit a shake proof washer.....Though they dont always work

[Ironwood]

There are different grades of loctite, that differ in strength. Look on the Loctite website and choose a grade to suit the application.

Other than this, what about using a spring washer, or nyloc nuts if there is a nut on the end of the bolt. I have also seen bolts with a nylon insert on the end of the thread (though these are not common).

Distorting the threads with a hammer blow, could cause the threads to pick-up when undoing, causing damage that could ruin the thread.

[Woodwould]

Nylocs (elastic stop nuts) are good for general use, but where there is a lot of vibration, you'd be better off with all-metal locking nuts like K-nuts etc.

The old way of locking threads was to use a pair of lock nuts (jam nuts) - about half the height of regular nuts. One is tightened as normal and the second one is then tightened against the first, thereby stretching the male thread and preventing the bolted joint from loosening.

If you can't locate all-metal locking nuts, or lock nuts, then try two regular nuts in the method previously described.

[Skew ChiDAMN!!]

:whs:

I'm not a great fan of spring washers, so in high-vibration places I'll often add another nut as a locknut "just in case."

Given enough thread, I'll use ordinary nuts so I can use an open-end spanner on the first nut to hold it while I "pinch" up the second, especially when I want only a specific tension on the first. (eg. the nuts on a lathe banjo or similar cam-lock system.)

[Tiger]

I should have also added to the initial post that the threads where I would use this method on, either have an irregular thread, the other does not have much thread protruding to use a jam nut.

[Andy Mac]

There are some pretty trick lock washers around. I bought some two piece items a while back, called disc lock washers (http://www.disc-lock.com/products-detail-original-locking-washer.htm), with finely machined serrations on mating surfaces, and they were extra hard to undo the nuts.:2tsup:
There is another type, one piece, made by Schnorr (http://www.schnorr.com/safetywashers.html)
My first choice though would be Nylock nuts.
I have more permantly fixed nuts (like on trolley wheels) by carefully centre punching the seam between thread and nut, to deform both. They can be undone, but a tad butcherous... but prolly less than putting a tack of weld on them and grinding off later!:p

Cheers

[Chris Parks]

Loctite is not permanent if the correct grade is used. An emergency version can be found in nail polish or superglue though neither are quite as good!

You could squeeze a nut in a vise and slightly deform it but getting it just right would be more a**e than class I would reckon.

Nylocs are good but if in a critical situation should not be used more than once, or so the manufacturers advise. I use them multiple times but then I can tell just by tightening them if they are stuffed. K nuts are aviation grade and a step above common nylocs and are not so easily obtained, but they are good.

[NCArcher]

Another method is to drill a small hole through both nut and bolt and insert a split pin or wire the nut in place. Easy to remove and virtually impossible to vibrate off.

[BobL]

Nylocs are good but if in a critical situation should not be used more than once, or so the manufacturers advise. I use them multiple times but then I can tell just by tightening them if they are stuffed. K nuts are aviation grade and a step above common nylocs and are not so easily obtained, but they are good.

I learned this on my chainsaw mill which has about 10 nylocs on it. After half an hours use they were nearly all loose. The reason was that I made - disassembled and remade the mill maybe 3/4 times and each time the nylocs became looser and looser. Finally I replaced all the nylocs and they worked OK for a while, but they still came loose and now I use removable loctite on everything except the adjustable bolts for which I use double nuts.

I notice on my newer 066 Stihl Chainsaw, that uses torx bolts, that the undersides of some have "finely machined serrations on mating surfaces" which seems to be effective because that thing vibrates like crazy and the bolts seem to stay on fine. The other thing I noticed was that some of the nuts used on this chain saw seem to have the outside thread of the nut crushed, "out of round" - they are like serious nylocs - without the nylon.

[Woodwould]

The other thinn I noticed was that some of the nuts used on this chain saw seem to have the outside thread of the nut crushed, "out of round" - they are like serious nylocs - without the nylon.

K-nuts - or a generic version.

[BobL]

K-nuts - or a generic version.

Ah Haa!

[Bob38S]

Have had some success in the past with nail polish, super glue as stated above but have also used plumbers thread tape in an emergency.

However, as others have stated above, the correct Loctite works the best.

[bsrlee]

I'm surprised Woodwould didn't mention this one, its about his preferred vintage.

Back in the days before Loctite, they used boiled linseed oil on the thread - in a few days it congealed and kept the nut in place but was soft enough that you could undo the nut (or back out the bolt/screw) with the correct tool. It could even be scraped off & it yeilded to heat if it gummed up too much. If you have ever tried to unscrew the lid on a bottle of linseed oil based finish you know how hard it is.

[Woodwould]

I'm soooooo old I'd forgotten about using linseed oil.

[Barry_White]

Another solution is a castellated nut and a split pin.

[Master Splinter]

...a quick pass with the arc welder is good at making sure nuts don't come off

Or peen the exposed thread down a bit with a hammer and drift.

[BobL]

Here's an old school one I saw just a couple of days ago. Drill a shallow hole in the end of the bolt and use a centre punch to marginally splay the end of the bolt. If you do it right you can still get the nut off and doing so restores the bolt to it's former diameter for reuse.

[Woodwould]

... and doing so restores the bolt to it's former diameter for reuse.

... or stretches the nut beyond its safe use! That method would be for one use only. I wouldn't like to use either component again after doing that.