Loctite

[Steambuff]

Hi,
I am just in the process of fixing 31'2" gauge loco wheels to axles. I intend to use loctite, has any members any thoughts on this and which loctite is best suited the ones I have seen is 601 or 603.

Thanks

Steambuff

[the_viffer]

601 is discontinued. 603 or 638 might be good choices. Check out www.loctite.com

I had a wheel slip on the axle last year. Very glad there was a drilling half in the axle and half in the wheel to allow speedy relocation. Shame the drilling was fitted with a 1/16th roll pin which collapsed when the glued joint went belly up.

[greasemonkey]

I had the same situation when a wheel came loose on one of my engines. I ended up having to carfully set it up in the lathe with a DTI to get the quartering the same on all of them. All wheels are now secured with grub screws as well.

Andy

[waggy]

Dear Mr. Buff,
Loctite 638 is superb stuff! The only thing that shifts it when fully cured is heating up to a nice straw colour. If your wheels get this hot in service, coming loose would be the least of your worries!

Dave.

[the_viffer]

waggy said:

Dear Mr. Buff,
Loctite 638 is superb stuff! The only thing that shifts it when fully cured is heating up to a nice straw colour. If your wheels get this hot in service, coming loose would be the least of your worries!

Dave.

The received wisdom is that you can free Loctite joints with heat. This is true but only to an extent. If you heat to straw then then you can get the wheel off while it is hot. If you nuke the joint so that the adhesive carbonises it is much harder to remove.

[Steambuff]

Thanks for your replies, it has been of great use, I had considered the use of a pin between the axles and wheels, but thought i would get away without it on a 31/2" gauge, but for the little time involved I will do it, probably save me a headache later on.

Steam Buff

[Peter W.]

I've yet to glue my first wheel (5" gauge) but I can't put it off much longer !

The wheels are (mostly) a 'firm' fit on the axles, and i'm going to put wide grooves in the axle for the Loctite to fit in.

I was hoping that that would be enough.
If you put a pin between wheel and axle as a key, won't that spoil the circular strength of the Loctite to some extent ?

All background gratefully received.

[the_viffer]

peterw said:

I've yet to glue my first wheel (5" gauge) but I can't put it off much longer !

The wheels are (mostly) a 'firm' fit on the axles, and i'm going to put wide grooves in the axle for the Loctite to fit in.

I was hoping that that would be enough.
If you put a pin between wheel and axle as a key, won't that spoil the circular strength of the Loctite to some extent ?

All background gratefully received.

Circular Strength = Urban Myth. There is a story going round that you need a complete circle of Loctite to make a bond. It just ain't so. Even if it was wouldn't a coat of Loctite on the pin form a circular bond. I think the peel strength of Loctite might be fairly low but that is not going to be a problem in a wheel/axle arrangement.

Loctite cures in the absence of oxygen. You have to have a biggish gap to get a fair amount of Loctite in the joint. The first lot of Loctite scavenges the oxygen from the remainder and allows the rest to set. If you have a small gap then it doesn't work well as there is not enough left after the scavenge.

If you've a set of grooves I think it'll be a disaster as not enough air will get to your big reservoir of Loctite to cure it. Only the stuff in the narrow gaps will cure and that will not give you a strong bond.

I say either use Loctite with enough clearence to get a decent strength joint and desirably put a locating pin in case the joint should ever fail or if you have the skill and desire go for a press fit again optionally with a pin.

I strongly believe that the middle way will give you the worst of both worlds.

[waggy]

Peter,
Do not put reservoir grooves in your axles where the wheel sits. Loctite 638 will bridge a gap of .003" but strength diminishes rapidly if the gap any bigger. I made my axles .0015" under the wheel bore size. this allows plenty of space for the Loctite to work and set to full strength. The Loctite will happily bridge this small gap and will support the weight of your wheel evenly, ie, no run out due to having a gap! A level, CLEAN surface on both bonding faces is the best option.
Heating the joint to straw will release the joint, the Loctite will bubble when ready to let go.
If you doubt the strength of this stuff, make up a joint from scrap pieces of steel or cast iron, bond it and 24 hrs later try and break it. Try sticking a couple of CLEAN flat bits together, no clamping required just make sure all air dispelled and Loctite evenly spread in the joint. I've stuck all my name and number plates on my engines, some have been there for fifteen years!
When you prepare your joints and apply the Loctite, take care everything is clean and evenly coated. You can take your time as the compound will not dry until all air is dispelled from the joint. When joint assembled you have to be a bit quick as it gets hold fairly quickly. Have a trial first, may take an hour or so but time well spent.

Regards,

Dave.

[David Thompson]

I would just add, CLEAN means really clean, including degreasing. I have found "Clutch and Brake Cleaner" spray cans from the local auto goodies store to be excellent for degreasing jobs before using any sort of glue.

[Peter W.]

Many thanks for your replies -- very informative.

How long have I got to adjust a wheel when quartering ?

( Favourite ways of quartering now, that's
another thread ... )

Peter

[the_viffer]

peterw said:

Many thanks for your replies -- very informative.

How long have I got to adjust a wheel when quartering ?


Peter

Long enough. Curing time is variable depending on the adhesive you use, the size of gap and metal used amongst other things but you've several minutes. The spec sheet ex www.loctite.com will give you more info.

I don't recommend using the accelerator spray since you want to have time to adjust but more importantly since it reduces the ultimate joint strength.

What ever quartering technique you use you might want to think about having the axle vertical.

Watch out for excess adhesive running into the axle box. How do I know that can be a problem? Don't get me started.

[Peter W.]

'Several minutes' sounds OK -- any shorter and I might have trouble !

A few dry runs & the axle vertical ...

Thanks again