Chemistry lesson wanted

[Martin Shaw]

Afeter the arrival of the 7/8ths Bagnall in the autumn I have been contemplating a rake of slate wagons so a kit arrived as a try out to see whether a rake made sense. It came with wheels I didn't care for and the only suitable ones I had were on O gauge axles. Making two G1 axles is a simple turning exercise as seen in the bottom example and I decided oil blackening was more sensible than paint and a test is shown in the upper example. The only oil I could find in the garage was some 220 bearing oil which at 0deg is not far off steam oil for viscosity and I wonder whether it is entirely suitable for this exercise. The test axle isn't too bad but not wholly successful. Would for example a lower flash point vegetable oil be better. I welcome any thoughts on this.
Regards
Martin

 

[simond]

Martin, the only experience I can offer is blackening coupling hooks.

I hate brass hooks on rolling stock, it looks daft (and is very common, even on expensive, beautifully painted models!) so where I’m building something I use Premier steel hooks, heat them to red and drop them in a little pot of Wahl beard trimmer oil. Other breeds are available.

It’s a light mineral oil, which I use for almost all lubrication of models. It blacks steel perfectly well.

hth
Simon

 

[Rob Pulham]

I have used 3 in 1 oil in the past but now I use more household friendly cooking oil (in my case out of date olive oil). As ever the secret to successful blackening even when heating up, is making sure that the item being blackened is clean before hand.

 

[Martin Shaw]

Thanks Simond and Rob. Whilst listening to my monday evening fix of Cerys I arrived at a conclusion, the axle centre could usefully be blackened whilst the journals will be all but invisible and oiled anyway and therefore won't rust. Whilst I polished the axles with Scotchbrite before blackening I think a chemical clean with Acetone or celly thinners might also be worthwhile. I have ordered 2M of 5mm EN1A which might come tomorrow but at the mo I have no more stock. Once I have decided the procedure it becomes a batch exercise to alleviate boredom. I'll have a further tryout in due course.
Martin

 

[Martin Shaw]

I had a further go at this today using some vegetable oil and a lower temperature, dull red instead of cherry red. I think it was more successful, the blackening is more even although it really is a thin coating at best.


It polished up ok and the journals burnished back to shiny quite easily. The wheels pushed with a drop of super glue, it's all a bit academic as once the wagon side is glued on the wheelsets are trapped.



I made the axles 74mm overall which gives about 2mm endfloat or 1.5mm too much so the production batch axles will be that bit longer. The dimension came from the original Accucraft axles which were a suggestion instead of those supplied in the kit. They are curly spoked all nylon which are undoubtedly more prototypical but the steel wheels will give some additional weight to avoid derailments by privet leaves and similar detritus.

This is the setup in the lathe to press the wheels on, two turned ali mandrels hold the wheels square to the axle and the tailstock provides the urge. Simple stuff really but it works well, wheels with an insulating bush are always a bit of a challenge to keep square. I think thats sorted out all the procedures, when all the bits are here I can crack on.
Martin