In praise of plastic!

[Julian Roberts]

I've been making a fish train. Parkside, Cambrian, Chivers wagon kits. What a joy. They go together almost as easily as Airfix. All the detail, ready moulded on. So easy to 'weld' them together, and to drill or rework where necessary. Yes I know brass vehicles would be better and much more resilient....but I've made 10 wagons in the time it took to make the single Caley Coaches brass one.

It makes me wonder why there aren't more plastic kits for steam loco bodies... (chassis are a different matter of course in P4)

[Terry Bendall]

Plastic wagons do normally go together well but there is of course a place for different materials as my articles on wagon construction shows. I am part way through building two of the Rhumney Models etched brass fish vans and the use of this material does allow fine details to be included in a different way to a plastic kit. It does of course depend on whether anyone makes a kit of your chosen prototype and usually you will be stuck with whatever materials the kit designer has used.

It makes me wonder why there aren't more plastic kits for steam locos ...

Probably because of the complexities and cost of making the moulds.

Terry Bendall

[Noel]

Probably because of the complexities and cost of making the moulds.

Injection moulding machines are not cheap, either. All of these costs have to be amortised over the expected production of kits. Production of an individual wagon type may reasonably be expected to be a lot higher than production of an individual loco class. This has obvious implications for costs to the buyer.

Another consideration is that, apart from wheels, if provided, a wagon kit is self-contained, while a loco kit requires a chassis at least, and plastic probably won't be robust enough for that. This means more costs for manufacturer and customer, and more tools and skills required by the customer, who may not have them, nor see any need for them when they work, as most will do, in r-t-r OO. Again there are cost implications to this.

Ratio, Parkside and Ian Kirk started in an environment where 4mm r-t-r wagons varied between poor and very poor in standard, with a very limited range of types; current r-t-r has its problems with accuracy from time to time, but is greatly improved in both respects. I would not be surprised to see few new 4mm kits produced in future and even the disappearance of some existing kits as the economics of production change.

[Julian Roberts]

Yes Noel re chassis - I've amended my OP

[Guy Rixon]

It would be very good to have more moulded kits for coaches. These could be self-contained kits, like the wagons; much more saleable than locos, I reckon.

My understanding, from conversations on-line and at shows, is that the mould-making process is a lot cheaper than it was 20 years ago, at least for the kind of moulds that support a short production-run.

It's possible that the machines that mould wagon kits are too small to run moulds for coaches. But that only affects cottage-industry production. Presumably, a kit could be made in China, in a modern factory with proper machines.

[barhamd]

I saw some recent videos on Youtube where people had 3D printed in resin a mould to be used in injection moulding. They had a metal surround for the mould so it only had to cope with the compressive forces of the plastic being injected. They managed to make a two part mould and successful injection cast using it, seemed like the moulds were good for ~30+ castings.

David

[steve howe]

It interesting that the range of die-cast models in a wide variety of scales (not necessarily railway subjects) is huge, but this process never seems to have caught on much in model railway production.

Steve

[Will L]

Rosebud Kitmaster made a few locos and coaches which passed on to Airfix and eventually Dapol, but presumably they didn't sell well enough to encourage more. Others including Slaters did a few nice coaches, but as the Kirk kits proved if you tried to reduced the cost to the point the kits were viable, the quality didn't satisfy the sort of modeller who wanted to build kits. Anyway is not the current day remarkable wide range of ready to run models largely the product of plastic injection moulding. You can always hack them about if you must.

As for using die cast models, what were your Hornby/Wren models made of? Not to mention the chassis of most of the Plastic bodied RTR models which followed.

Or have I misunderstood something here.

[Julian Roberts]

Well Will I suppose I was overlooking the small Dapol range. Yes they are equivalent perhaps though I haven't made any since about 1967 when they were Kitmaster! But what is striking about the wagon kits available is the huge number and variety, as well as quality and value for money judging by this recent experience.

I wasn't including RTR models in my mind as they aren't kits. Yes it is very satisfying converting one to P4 with a bespoke chassis from Dave Bradwell/High Level/Comet. But getting a body isn't straightforward and can mean buying the 00 loco and chucking the chassis, a rather wasteful process and much more expensive unless obtained cheaply somehow.

[davebradwell]

I've heard it said, Julian, that Bachmann will sell you any part these days as long as you give them a number. Not tried it myself, though. They do seem to use a particularly gooey sort of plastic that doesn't pick-up the fine detail that the specialist kit makers achieve. This is most noticeable with joint lines like planks, coach doors and joints in cab roofs which must be made wider. Aren't many older rtr vans too wide?

Suspect many of our trains would be much shorter without rtr, however.

DaveB

[martin goodall]

Ratio once introduced a plastic kit for a Midland 2-4-0, but it didn't seem to get all that many sales, and I can't remember ever having seen a completed model.

I suspect that plastic loco kits may not be commercially viable on the whole.

[stephenfreeman]

Post by martin goodall » Sun Aug 15, 2021 11:44 am
Ratio once introduced a plastic kit for a Midland 2-4-0, but it didn't seem to get all that many sales, and I can't remember ever having seen a completed model.

I remember just, it was nearly 40 years ago building one of the Ratio kits for a friend in 00. It went well enough in the end plenty of speed but I don't think haulage power would be great - lack of weight - not too inspired by the motor either.

[David Knight]

The Ratio kit depended on the type of frame that came with it. Some were just brass overlays that weren’t much use others were more substantial. A friend built one in P4, CSBed it, added a HighLevel gearbox and a Mashima motor. It ran well IIRC. I have one lurking in my eventually drawer.

Cheers,

David

[steve howe]

As for using die cast models, what were your Hornby/Wren models made of? Not to mention the chassis of most of the Plastic bodied RTR models which followed.

Indeed Will, and the old Wrenn stuff were built like tanks! but you don't see diecast used much in our line of work, not for bodywork anyway, these days which was the comment I was making.

Steve

[pete_mcfarlane]

My understanding, from conversations on-line and at shows, is that the mould-making process is a lot cheaper than it was 20 years ago, at least for the kind of moulds that support a short production-run.

There's a huge variety of short run plastic aircraft kits coming out of Eastern Europe these days using such moulds. Maybe not as good as the current Airfix kits, but pretty good.

[MarkS]

Here is the ratio 2-4-0 mentioned earlier by Dave Knight... There was a fair amount of work involved, but worth the effort.
There was also a 4-4-0 version...

[LMS10640]

The 4-4-0 had plastic frames and wheels/axles as well! The wheel/axle mouldings were plated with a conductive material and the frames were brass bushed. The motor was unimpressive, but the kit made up nicely. It was quickly replaced by the 2-4-0 which had more orthodox wheels/frames but wasn't around for long either. As I remember, both locos used the same mouldings from the front of the smokebox backwards . The 4-4-0 made up as well as any Ratio kit of the time: a good try, hampered by lack of weight and a few technical issues.

Perhaps a case of trying to push the 'envelope' a bit too far?

David

[Julian Roberts]

Nice model by the looks of it! Don't quite see why a plastic model can't be stuffed with lead. Got my ex-Bachmann Crab loco up to 400g, with room for the motor.

Thinking about plastic chassis...of the Dapol range the mogul is the only one that could possibly be appropriate for me. I wonder what I'd use of the chassis, though plastic brakes save a huge amount of fiddling around to prevent shorts.

I wonder if the Dapol kit is an accurate body for your 9F chassis Dave?

(Bachmann) do seem to use a particularly gooey sort of plastic that doesn't pick-up the fine detail that the specialist kit makers achieve. This is most noticeable with joint lines like planks, coach doors and joints in cab roofs which must be made wider.

Yes the fine-ness of such line detail such is one of the things I've found striking about the wagon kits.

[davebradwell]

I have several of the Kitmaster 9Fs, Julian, a DJH kit and also a Hornby body. They were all a reasonable place to start once but I went for the Bachmann despite them getting the cladding on the firebox top wrong. Laziness might have had something to do with it. It took a pretty heavy bandsaw and milling session to carve out a space for a hefty gearbox in the firebox. I was on the final straight when I found that after years on the windowcill of shame, some of the modified Gibson wheels had cracked centres, possibly due to sunlight. It's never happened with others. I suppose I could do a Morgan on the Bachmann wheels and fit the Gibson tyres but there's a lot of them!

Returning to the main topic, I became concerned about adding large quantities of lead to plastic bodies which I thought would be likely to sag with time. My N2 kit includes an etched cradle to carry the tank side weight for this reason and I usually ensure a chassis carries as much weight directly as possible.

DaveB

[Stuart Firth]

Here is the ratio 2-4-0 mentioned earlier by Dave Knight... There was a fair amount of work involved, but worth the effort.
There was also a 4-4-0 version...

You have shamed me - that looks lovely. I have one of these in the drawer, bought from 'The Engine Shed' in Leytonstone High Road, about 1987. On many occasions have I removed it from the box, looked at the parts, and quietly put them away again. I must do something with it! Care to share what you did? I see the grossly overscale boiler bands are gone...

[MarkS]

Stuart, there was a thread here mostly about the chassis and CSB's -
https://www.scalefour.org/forum/viewtopic.php?f=19&t=1277&hilit=ratio
I built it back in 2009-10. I used the Percy chassis that came with it, and added brass bits from Gibson and Markits.
I don't have many photos of what I did although these may give an idea...
There was a lot of plastic "fabrication". I narrowed the wheel arches in the cab, modified the tender a bit.
All good fun, and someday I will build the K's Midland Single to go with it.

[Stuart Firth]

Thank you - most interesting !

[Julian Roberts]

Perhaps the answer to my original question is here?

viewtopic.php?t=4577&start=300