Which threadlocker formula?

[dpgibbons]

Loctite and other threadlockers come in strengths varying from permanent fix to removable with hand tools. I need to secure the tiny threads and nuts on 7mm wheels/cranks/sprung buffer shanks whilst still allowing ready removal.

 

Are the low strength threadlocker versions (Loctite 202 et al) safe for this? Or is there a better option?

 

 

Edited October 26, 2020 by dpgibbons

[Simond]

I really don't recommend putting threadlock on crankpins, because 12BA  screws are so small that there is a real risk of breaking one when trying to undo it.  Ideally, the nut should stay done up when tightened, but if not, a tiny drop of evostik or similar is a safe bet to prevent vibration causing it to loosen.  If it still comes undone, then you might want to look at the fit of the rods, which obviously should not bind at any point in the rotation of the wheels.  I use 10BA screws tapped into the back of the wheels and secured with epoxy, and I never threadlock my crank bushes to them.

 

Buffers are a different matter - they need to be set at some point so you can't "tighten them up".  A drop of threadlock will certainly work - the weak one is purple (222) - the guide is here;  https://www.henkel-adhesives.com/uk/en/products/industrial-adhesives/threadlockers.html#sb-How-to-Choose-a-LOCTITE-Threadlocker-7

 

you can also use evostik or similar, or a drop of paint or nail-varnish.

 

hth

Simon

[Hal Nail]

1 hour ago, Simond said:

Buffers are a different matter - they need to be set at some point so you can't "tighten them up".  

you can also use evostik or similar, or a drop of paint or nail-varnish.

 

I've never actually run any of my stock as the layout is still only 25 years into the gestation phase so haven't ever learn the hard way about this!

 

I did some rusting this morning and ended up with unused paint I had blended and was thinking what a waste. From now on I will have 4 or 5 wagons on standby for every session and do the buffers with the leftovers.

[Enterprisingwestern]

 

Whilst on the subject, I have a final drive cog, which, after a 4mm chassis re-build, is a tad loose on the axle, a quick roughen with a file or similar should take care of most of the gap, but would a threadlock fluid be a better option instead, or maybe both?

 

Mike.

[Phil Traxson]

7 hours ago, Enterprisingwestern said:

 

Whilst on the subject, I have a final drive cog, which, after a 4mm chassis re-build, is a tad loose on the axle, a quick roughen with a file or similar should take care of most of the gap, but would a threadlock fluid be a better option instead, or maybe both?

 

Mike.

I used Bearing fit rather than threadlock, can't help with code number because it was a long while ago (25+years).  I fitted bush to gear and then both to the axle to put Romford axles, using original Hornby nylon gear, into a Hornby  jinty chassis for a 7mm narrow gauge loco. I used bearing fit that I had in my toolbox as a maintenance fitter, it is designed to expand slightly as it goes off and centralises the axle. The loco is still in use and its never come loose. I filed a small flat on the axle and a slight "V" in the hole in the bush and when it had set did likewise with the outside of the bush and the inside of the gear, the thread lock then forms a key as well , a bit of a belt and braces method, the thread lock would probably have worked without the filing.    

Edited October 26, 2020 by Phil Traxson
Missed a letter

[Ian Smeeton]

Try Andy York.

 

Whatever he uses to lock threads seems to be VERY effective.

 

Regards

 

Ian

[Simond]

Be wary of applying threadlock or similar to plastic gears on axles.  As noted above, the locking compound swells up to fill every available gap, and will stress the plastic.  This may lead to a split gear.  
 

In this case, epoxy may be a better, safer, bet.

 

note also that some metals don’t catalyse the locking compound polymerisation.  Steels will, and brasses, iirc, but stainless and ally may not, presumably due to their oxide layer.

 

atb

Simon