The effect of oil on plastic

[andyman7]

I've posted this here as it will no doubt be a familiar experience for anyone who has repaired Triang or similar model railway items with plastic parts. In the 1960s and 70s, any requirement for oiling parts was normally met by the application of a common household mechanical oil such as 3-in-1 of the kind on lawnmowers, bike chains etc. The problem with these is that they degrade plastic over time. Of course, the idea was that only the metal mechanical parts got oiled but (over) liberal application meant that surplus lubricant often ended up coating piston blocks, motion brackets, the insides of bodies etc. 

 

Often when opening up an old model, the result is similar to entering Pharoah's Tomb, everything perfectly preserved until exposed to daylight and then it crumbles before your eyes. In the most recent instance, a 1980 production R852 Ivatt 2-6-0 when tested had the valve gear come loose. On examination up, a clean split in the cylinder block can be seen, which when removed is revealed to have been sitting in a pool of oil for about 40 years......fortunately replacements are still obtainable  (phew!). 

 

Needless to say, any overhaul of these old models involved complete removal of any old oil, and fresh lubrication with a modern synthetic plastic-safe oil.

 

 

 

 

[Kubes]

And the wheels of Tri-Ang coaches which distinctly upset a ten year old Kubes!

[Il Grifone]

3in1 is nasty stuff (says he who cheerfully used it - a large can for 1/3d as opposed to a tiny glass (yes) vial for 6d appealed to a young Grifone). It wasn't recommended back in the the day (too thick - its deleterious effect on plastic showed up later). Luckily Dublo mechanisms don't use much plastic other than nylon which seems immune or have I just been lucky?

I always assume that if the label doesn't state, "plastic safe" it isn't (and I'm not too sure when it does!).

Kadee supply graphite for their couplings. I find a soft pencil works well and goes/stays where you want it.

[RedgateModels]

The original Evening Star tender chassis was a particular victim of this. To make matters worse the top surface where the motor and weights sit is very thin. Sadly replacements are not available and can lead to an otherwise good engine being consigned to the breakers yard for parts

 

I have one very bad example at the moment.

 

All Triang insulating bushes on axle ends suffer, ok until you need to remove wheels for reprofiling etc. New bushes will always be needed.

[Dubloseven]

At one time, many years ago and not knowing any better, I would give Dublo mechanisms a liberal coating of WD40.

 

After a little running in they would go like the proverbial 'bat out of hell' and also the slow running would be much improved and they're all running fine to this day although my servicing standards have improved since then.

 

Don't think I'd be inclined to use WD40 on anything more recent though.

 

Regards, Cliff.

[RedgateModels]

A lot is said against WD-40 but it is very useful. I buy it in 5L drums now that come with a new trigger bottle each time. Long gone are the days where you never get all the stuff out of an aerosol before the gas ran out

 

brilliant cleaner, easer of rusted components etc. Although it does have some lubricating properties I'd not use it as such though. Never on a model loco LOL

 

 

[andyman7]

1 hour ago, Il Grifone said:

3in1 is nasty stuff (says he who cheerfully used it - a large can for 1/3d as opposed to a tiny glass (yes) vial for 6d appealed to a young Grifone). It wasn't recommended back in the the day (too thick - its deleterious effect on plastic showed up later). Luckily Dublo mechanisms don't use much plastic other than nylon which seems immune or have I just been lucky?

 

44 minutes ago, RedgateModels said:

The original Evening Star tender chassis was a particular victim of this. To make matters worse the top surface where the motor and weights sit is very thin. Sadly replacements are not available and can lead to an otherwise good engine being consigned to the breakers yard for parts

Nylon isn't affected (the bearings on the X337 armatures are white Nylon), it's polystyrene type plastics that suffer. I too have an early 9F (R550 black one) with crumbling chassis, as you say no spares are available. Maybe Peter's Spares will remould it one day? I'd forgotton about the wheels, the ones with pinpoint axles don't need oliling but that wouldn't stop some overenthusisatic modellers and eventually the wheel disc splits.

The other classic Triang failure I had on a few occasions was the roof of the R357 A1A - liberal oiling of the worm gear results in a neat spatter line across the underside of the roof, which is secured by a screw but also has a clip above each cab. The result is that one day, the roof is levered off and splits clean in half.

Edited August 20, 2020 by andyman7

[Il Grifone]

I had noticed some Evening Stars on sale less power tender. Failure of the latter would explain it. I'm half tempted as mine tends to seize when running. There doesn't appear to be anything wrong other than an excessive amount of slop. Ten coupled wheels would be allergic....

[BR60103]

Many decades ago one of the magazines had an article on the effects of oil on plastic bits. They would soak a part in oil for a while and then show it beside an original. The usual effect was a non-uniform swelling. 

Soon afterward at least one lubricant maker came out with "plastic compatible" oil.

 

One of my school friends found a cheap (free) source of oil in his mother's kitchen. Many of his Kitmasters never rolled again.

 

[Il Grifone]

Back in the day, an article in the model press (RM?) on motorising the Kitmaster 'Pug' stressed to use vegetable oil for lubrication. They obviously knew already of the effects of mineral oil on plastic.

Later on I tried it. It worked for a while, but soon seized up and began to smell....

[Halvarras]

Over 50 years ago I had a Triang L1 4-4-0 which I lubricated with 3-in-1, and in 1974 noticed cracks had appeared in both sides of the boiler, apparently seeping a little oil. I opened it up and immediately noticed that the cracks and oil splatter were in line with the motor's worm gear, so I quickly realised that the penetrating oil was penetrating to an undesirable extent. This prompted my first-ever letter to Railway Modeller to alert others to the problem. It also explained the common failure of the plastic baseplates on the Triang A1A motor bogie, not helped by the original recessed securing screws which weakened the component at the corners - these recesses were later 'tooled out'. Luckily replacements were obtainable. The L1's boiler was cleaned out and reinforced internally with Plasticard.

IIRC Trix coach bogies and wagon underframes were moulded in a tough material they called 'graphite-filled nylon' which made them incredibly free-running and avoided the 'axle-drilling' which plagued Triang rolling stock, due to poorly-finished pinpoints.

[Il Grifone]

The A1A baseplates are a sought after spare today, though many are brittle from the oil effect. I was considering making some from PCB, but have sufficient spares at the moment. ('Andromeda' might need one*  ) All the ones I've seen have the recesses, There isn't much clearance for the screws without.

 

* I know she's a 37, but they use the same bogie.

Edited August 22, 2020 by Il Grifone