Inward bow on RTR open wagons

[gordon s]

I've just started weathering a whole crop of Bachmann wagons and noticed several of the open top wagons, such as coke and 16 tonners, have an inward bow of a mm or two. They have been in storage (in perfect conditions) for many years and it's only come to light as I've started to work on them.

 

 

Filled wagons won't be a problem as I suspect a false floor will push out the sides. but what to do with empty ones?

 

I thought about machining up a block that fits inside and then applying gentle heat from a hair dryer to see if it soften the plastic and allow it to reset, but then it depends on the material they have used. I guess it also depends on the wall thickness as well.

 

Any ideas how to solve the problem?

 

 

 

 

[Rowsley17D]

Hi Gordon, this is a common problem with new stock so I doubt storage time will not have affected your vehicles. Hopefully the chemists will be along to say whether the plastics used by various manufacturers are thermosetting in which case heat will not solve the problem or thermoplastic is which case it will, probably. It would have helped if the bow was outwards, at least it would have been prototypical, but I guess the physics determines it otherwise. Have you an unloved wagon on which you could experiment?

[gordon s]

I'm guessing it is thermoplastic rather than thermoset as it is soft rather than brittle and I'm sure if I touched it with a soldering iron, it would melt easily.

 

Sadly I don't have any old or unloved wagons yet...

 

I will give it a go if nothing materialises, but suspect it is a common issue that others may just live with.

[Enterprisingwestern]

 

In best Allo Allo fashion, I have tried this only once, but it worked.

Cut a piece of thin wooden dowel to just over the width of the internal dimension and smooth off the ends, wedge it in the wagon with the sides bowing outwards and then gently waft a hair dryer over the wagon set at high heat but from a distance.

The reason I have only done it once was because I was trying to get the wagon sides to bow outwards as many mineral wagons are in real life. It worked initially, but over time about 50% of the bowing straightened itself out and I had a wagon with not far off straight sides, that's why I think it might work for small amounts of bowing, overcompensate, and it will probably come back in a tad.

PS. No warranty is implied or inferred with this method!

 

Mike.

[MR Chuffer]

I've noticed this too, a couple of Bachmann 7 planks recently acquired in last 9 months, not used yet, but not the 5 planks nor Oxford models. Mine won't be a high detail layout when complete so I'll just live with it...

[Rowsley17D]

It's not just RTR stuff that suffer, many kits have the same problem.

 

 

 

[cypherman]

Hi all.

I am not sure if this will work, But what if you put a former inside the wagon t push out the sides. The gently heat the side so it becomes more flexible allowing it to take to the new position. then let it cool down. This will hopefully let the plastic sides set to the new position created by the former.

OOPs looks like some one beat me to the punch on this one.. I would say though that I would use a block of wood rather than a dowl to make sure the pressure pushing out along the wagons side is the same all along it's length.

 

Edited May 6, 2020 by cypherman

[petethemole]

With a merchandise wagon the sides would bow out slightly but as three almost flat planes, due to the stiffness of the door in the middle.  I've treated some wagons by glueing chunks of kit sprue across the middle, but these were finished with loads covering the cross pieces.

[gordon s]

I'm chuckling away to myself, cypherman,  as that's where I started.....

 

"I thought about machining up a block that fits inside and then applying gentle heat from a hair dryer to see if it soften the plastic and allow it to reset, but then it depends on the material they have used. I guess it also depends on the wall thickness as well".

 

Glad to see I'm not the only one who misses things....

 

The down side of the block approach may well be it will shrink back again. Going outside the norm line between the two corners could be a better solution as it should shrink back to straight.

 

39 minutes ago, MR Chuffer said:

Mine won't be a high detail layout when complete so I'll just live with it...

 

Don't kid yourself, neither will mine, unless I live to be over a 100......

[gordon s]

4 minutes ago, petethemole said:

With a merchandise wagon the sides would bow out slightly but as three almost flat planes, due to the stiffness of the door in the middle.  I've treated some wagons by glueing chunks of kit sprue across the middle, but these were finished with loads covering the cross pieces.

 

Interesting thought. Rather than a dowel, I could use a block the same width as the door section, but slightly wider than the cross width of the wagon.

 

Mmmm...Watch this space for some flat or broken wagons...

[34theletterbetweenB&D]

Wagon heater here. In my experience with both kit and RTR wagons, the best method I have found is a rectangle of hardboard as the 'stretcher' to fit inside the top edge of the wagon across the width of the door, because the bulgy look in particular typically shows some evidence of the door aperture. Then direct the heat under it with your hot air gun or whatever, on the inside of the body. If doing a given type of wagon in bulk it is possible to make the 'reset' by a timed heat application.

The correction - so far - appears permanent, that's a dozen years on.

 

What with being lazy and all, I initially sorted the wagons so that as many as possible of those with inward curved sides went in the 'to be loaded' pile where the action of adding a load would correct them.

[gordon s]

Thanks 34C. I tried with a hair drier, but the heat was insufficient. A little nervous about using a hot air gun, but it makes much more sense.

 

I hear the Salvador Dali look for 16 tonners is much appreciated in the art world...

[jcm@gwr]

An alternative approach to the hair dryer/hot air gun, assuming that you can separate the

body from the chassis (or at least remove the wheels), would be to immerse in hot water,

you could then quench in cold water to 'set' it.