Not sticking something with Loctite

I am making 'Locomotion' and coming on well even if it is a bit big for a Myford. I normally Loctite wheels on with great success using a quartering jig but on this loco the wheels aren't quartered (no problem) and one wheel shares the stub axle with an eccentric which obviously needs to be adjusted, there is no gap between eccentric and wheel. How can I Loctite the wheel and not the eccentric?

Hello Phil,

I am not familiar with the joint geometry, but is it not possible to assemble the eccentric on the axle and position it out of the way for the wheel attachment, bringing it into position once the Loctite on the wheel joint is cured and set?

I would add a drop of oil to the interface between wheel and eccentric when nestling them together again.

Regards Brian

The geometry is such that the eccentric fits snugly between the wheel and a shoulder on the axle, no possibility of assembly after sticking the wheel. I thought of oil but either the oil or the loctite is bound to get somewhere it's not wanted

candlewax rather than oil as it stays where put only. Basically any contaminant for the non-joint face.

Thinking outside the box a little, and this would require a little experimentation. How about different sorts of loctite. Low temperature breakable joint on the eccentric, maybe screwloc or some such, and high temperature high strength shaft grade for the wheel. Assemble the axle and eccentric, wait for it to go off and then the wheel. Warm the whole lot up until the eccentric bond breaks and there you go. It will be clear that I am relying on the loctite on the eccentric to keep the shaft grade out of the joint. Be worth a bit of a go to see if it works on some scrap stock just for fun.

Martin

Use a press fit instead?

Mask off with nail varnish, just don't let Her Indoors see you take it.

Good thoughts everyone; I won't do press fit as I haven't got a press, my chances of getting it right first time are slim and it can't be undone. Nail varnish (or Tippex) seems good, worth considering. Candle wax sounds very promising, my choice at the moment. The wheels would be pinned with 1/8th silver steel rod when coupling rods are fitted and wheels still go round so super strong bond not too important, 1" dia. cylinders at 50psi not too challenging either

Hi Phil,

I am afraid all the above are not guaranteed of success.

A number of alternatives...

1. I presume the eccentric is a slip eccentric? You can work out precisely the required position of the eccentric and then fix at same time as the adjoining wheel. The exact angle isnt too particular with a slip eccentric.

2. Redesign the axle so the eccentric can be moved away from the wheel whilst it is curing.

3. Fit a split eccentric as per fullsize which is quite easy to do in 7.25"g

Cheers,

Julian

Edited By julian atkins on 15/06/2016 21:52:28

If I had this to do I would:

- Spray the eccentric inside and out with teflon spray (or silicone if that was all I had).

- Place eccentric on shaft.

- Wipe the protruding piece of shaft with a cloth moistened with solvent (not dripping). Several times using clean areas of the cloth. Likewise clean the wheel inside and out. It might be a good idea to spray a little teflon on a Q-tip and wipe on the inside face of the wheel - avoiding the bore of course.

- Apply Loctite in a thin film to the inside bore of the wheel only. Leave an uncoated area at the end that goes towards the eccentric. (Q-tips are useful for smearing the loctite; also, when moistened with alcohol, for cleaning any contamination of the inboard end).

- Assemble wheel to shaft. Wipe off surplus Loctite from the outboard end with a dry cloth. Let the joint set for 24 hrs and then clean any remaining surplus Loctite with alcohol. (I don't use alcohol for clean-up before the Loctite is set for fear of it wicking into the joint and preventing proper curing).

Edited By Bandersnatch on 16/06/2016 01:31:19

As I understand it the eccentric needs to be timed after the wheel is fixed, and the 'timing' is in relation to the wheel, nothing else. So, why not fix the eccentric (using Loctite or any other method) and then when the glue has set, add the wheel, perform the timing process, and fix the wheel?

Or does that introduce some other problem(s) ?

Regards, Tim

Hi Tim,

I think that was my suggestion 1.

Hopefully Phil will reply to our suggestions.

Cheers,

Julian

Thanks for thoughts. I have decided to use a heavy oil / wax and mask the axle so the oil goes where it is supposed to, I will also put oil on the inner face of the wheel and apply Loctite carefully inside the wheel with a cotton bud. Only one wheel has an eccentric and I will do this wheel first, if it goes wrong it can go in the oven without much loss. If it works then, after sorting out the coupling rod, I will pin the wheels from the front face with 1/8 silver steel. I will let you know how I get on, probably in a week or two as I still have to make the crank pins and these have spherical ends on the drawing ! Thanks again, Phil