Thread sealants

[Richard_C]

I'm making a few fittings for percussion kit. No special high loads but will be subject to vibration. I can use nyloc nuts in most places but not all.

When I used to fix car engines back in the 70's, it was copa-slip for threads you wanted to undo, red (or green?) Hermatite for stuff you wanted to stay put. It doesn't exist any more, my initial thought is a smear of clear silicone sealant on the thread but any other suggestions welcome. The objective is to prevent any looseness and noise.

Thanks

 

[--Tom--]

Loctite comes in different grades depending on torque needed to break it

 

[Daniel2]

As @--Tom-- says, Loctite is your friend.
Loctite 270 would do.

 

[Bod]

Be a little careful with Loctite, not so much the locking qualities, which are good, but the surface it might get on to.
We used to use it to hold bolts clamping perspex type sheets, this would crack over time around the bolts.
Switching to a product that dried on the bolt threads before using, stopped the cracking entirely.

Bod

 

[Richard_C]

Thanks all. I had completely forgotten loctite brand, probably 30 years since I used any

 

[AES]

+1 for Loctite (there are several different colours & numbers according to what you want to lock - nuts/bolts, bearings into housings, undo again later, etc, etc). Local dealer should have info sheets free, which are quite helpful.

Also very similar I think, just a different brand name (AND colours of course!) is by, I think, Dow Chemicals of USA and called Fastlok.

Agree also with the above, some Loctite will reach badly with "some" plastics. If in doubt, make sure the 2 don't get together.

 

[Inspector]

Permatex is another maker of thread locking products among other sticky things.
https://www.permatex.com
Aviation sometimes use bolts and screws with a nyloc type rod in a slot cut the length of the threads or a piece installed in a hole and others that come with a dry compound on the threads. Both types keep the fastener in place. Something like them could be an option if you can find some in the sizes that suit your applications.
https://www.aftfasteners.com/threadlockers-nylon-patches/
Pete

 

[AES]

In the same/similar vein to Inspector (Pete) above, do you have to use a sealant at all Richard? What about the "obvious" (and commonly available) locking washers? There is the "single coil" type and the "star" type (with both inside and outside "wings"). These will often take up less length that a nyloc or oddie nut or similar and may help if you've simply run out of free thread length on the bolt.

 

[hawkeyefxr]

Copper slip still exists and is used a lot on car and motorcycle brakes to stop the squelling of the brakes.
As someone else said, loctite of many grades. Loctite 413 is good for stopping nuts and bolts from working loose.
They also do one that is permanent, you will never get it undone, and I have tried just because they say it can't.
It's used on raised floors in office type places.

 

[Dave Moore]

I'm making a few fittings for percussion kit. No special high loads but will be subject to vibration. I can use nyloc nuts in most places but not all.

When I used to fix car engines back in the 70's, it was copa-slip for threads you wanted to undo, red (or green?) Hermatite for stuff you wanted to stay put. It doesn't exist any more, my initial thought is a smear of clear silicone sealant on the thread but any other suggestions welcome. The objective is to prevent any looseness and noise.

Thanks

Hi,
Loctite 55 is a ptfe string that has a compound that sets. It’s only about £10 and we use it all the time for pipe threads and makes a great seal. Other Loctite products in liquid form will probably be very expensive and of course you need to be carefeful you don’t block the holes. With Loctite 55 you only need to wrap the string in the clockwise direction (looking at the thread end on) and it goes in the thread groove. You can probably get smaller size roll for less than £10. Available at BSS and I’m sure many other places. I highly recommend it, whereas we don’t often use ptfe tape which we only use on things we want off again like pressure gauges.
Regards,
Dave

 

[Phil Pascoe]

Copper slip still exists and is used a lot on car and motorcycle brakes to stop the squelling of the brakes.
As someone else said, loctite of many grades. Loctite 413 is good for stopping nuts and bolts from working loose.
They also do one that is permanent, you will never get it undone, and I have tried just because they say it can't.
It's used on raised floors in office type places.

Commonly known as superglue?

 

[clogs]

Used to work a lot on old crawler cranes etc…..
they are always up to the axles in mud n gunge…..
there were bolts that had to be tight but at the maintaining schedule they had to be undone….we’re talking 2”--50mm diameter stuff….
we found over the years copper slip mixed with a little EP 80 gearbox oil did the trick….the oil stopped the c/slip drying out….
try getting a 2” dia bolt out of a 40 ton iron casting when. It’s seized…lol…

 

[Phil Pascoe]

A guy used to service our cars years ago. I watched him one morning, he was meticulous. He wire brushed and copaslipped some bolts before replacing them and I asked if he always did it. He told me he did his apprenticeship the old fashioned way - the day he qualified his boss retired. He was taught that every nut, bolt, stud etc. should have loctite put on it if it wasn't supposed to move, otherwise it should be copaslipped as he might be the poor sod who the job back seized up a few years down the line.
It seems a sound rule to me - it's worked well for me for the 25 years since he told me. The first thing I've done with a new (old) car is to undo the wheel nuts or bolts, clean them and copaslip them - you can guarantee if you can't get one off it'll be 1/ dark, 2/ raining, and 3/ the car will be in everyone's way.

 

[Daniel2]

That's pretty much what I do.
If a thread isn't supposed to have a thread locking compound,
it gets a dose of copaslip.

 

[Fergie 307]

A guy used to service our cars years ago. I watched him one morning, he was meticulous. He wire brushed and copaslipped some bolts before replacing them and I asked if he always did it. He told me he did his apprenticeship the old fashioned way - the day he qualified his boss retired. He was taught that every nut, bolt, stud etc. should have loctite put on it if it wasn't supposed to move, otherwise it should be copaslipped as he might be the poor sod who the job back seized up a few years down the line.
It seems a sound rule to me - it's worked well for me for the 25 years since he told me. The first thing I've done with a new (old) car is to undo the wheel nuts or bolts, clean them and copaslip them - you can guarantee if you can't get one off it'll be 1/ dark, 2/ raining, and 3/ the car will be in everyone's way.

Another good tip is where you have a bolt with a threaded portion exposed under the vehicle, Land Rover, Jeep etc. Wipe it over with waxoyl or similar and then shrink wrap it. Bit time consuming but well worth it when you have to get it off two or three years down the road.

 

[hugov]

Commonly known as superglue?

Actually no – superglue (cyanoacrylate) doesn't give a particularly strong bond between metals, especially if there is even the smallest amount of oil on it (and I've never found a way of cleaning oil out of internal threads...). CA also won't cure properly in an airtight space between tight fitting components, as it needs moisture from the air to cure.

The Loctite retaining compounds and threadlockers will cure anaerobically (without air, or moisture from it), will be stronger bonding metal to metal (seeing as they're designed specifically for that, esp. the retaining compounds, which you can use as a general purpose metal glue), and generally will tolerate a slight film/residue of oil in my experience (although you still should clean the surfaces).

 

[AES]

Actually no – superglue (cyanoacrylate) doesn't give a particularly strong bond between metals, especially if there is even the smallest amount of oil on it (and I've never found a way of cleaning oil out of internal threads...). CA also won't cure properly in an airtight space between tight fitting components, as it needs moisture from the air to cure.

The Loctite retaining compounds and threadlockers will cure anaerobically (without air, or moisture from it), will be stronger bonding metal to metal (seeing as they're designed specifically for that, esp. the retaining compounds, which you can use as a general purpose metal glue), and generally will tolerate a slight film/residue of oil in my experience (although you still should clean the surfaces).

Absolutely correct. Cyanoacrylate ("super glue") is a much different animal chemically. I'm not a chemist, far from it, but if you read the info sheets on both Loctite (and the other brands, which are all anaerobics) and CA (all brands), which are available on line, you'll see that hugov is spot on.

 

[Spectric]

Hermatite was a gasket sealant, one colour set and the other remained flexable then I remember blue hylomar before silicon came along and solved many leaks and probably did more for the enviroment than many COP26 policies.

 

[Keith 66]

Loctite comes in various grades for different jobs, then there is loctite engineering adhesive, very permanent stuff indeed. All will break down & let go it you get them hot enough 170 degrees will do it. Soldering iron or small butane torch will release any of them. Epoxies will also fail at such temperatures.
Copaslip is good stuff & i have used much of it on classic cars & boats, funny thing is for ultimate corrosion resistance best stuff i have ever found for underwater use in the sea was Stockholm tar. Dip a shackle pin in that stuff & it can be in the sea for years & still come undone, the threads will still be shiny.

 

[Duncan A]

Copaslip is wonderful stuff but does tend to wash out, we used it mainly for higher temp stuff where it helped with disassembly .
Lubricants and anti-seize products shouldn't be used on torqued fasteners without checking the instructions first - it can make a massive difference to the stretch of a bolt, especially if it gets under the face of a nut.
None of which applies to the OP's requirements!
Duncan