Die-cast models?

[alexl102]

In recent years, Hornby have started to produce more models using die-cast metal for the locomotive body. I'm totally unfamiliar with Bachmann  locos having never owned one - are there any/many Bachmann locos which use die-cast metal as part of the model? Is there any way to tell which when buying second hand?

[G-BOAF]

Many recent Bachmann steam locos have diecast running plates. Boilers are (all?) plastic.

Personally I'm not a fan of diecast for the sake of it, rather if functionality/traction requires it. There are some reviewers online (one in particular) who seems to mark down when a model has little/no metal bodywork, but as Rapido have demonstrated with their excellent birmingham bus, the level of surface detail possible in plastic in terms of crispness is better than metal.

[The Johnster]

I really don't think that there is any inherent superiority in either material, and the choice is made by production engineers at the planning stage, informed by production methods and costs.  Both die cast and plastic can be tooled to produce very fine detail indeed.  The advantage claimed for die cast metal is that it increases traction weight, but a loco with a plastic body can use the extra space allowed inside it to contain bigger ballast weights.  It is an issue because by and large UK outline RTR locos are not capable of hauling realistic loads at realistic speeds up realistic gradients, and the space for ballast is constantly being eaten into by the demands for DCC chips, speakers, lamp wiring, and other bells and whistles, literally in some cases...

 

The debate goes back a long way, though, to the competition in the 50s and 60s between Rovex Triang and Hornby Dublo.  The HD afficionados claimed that die cast was better just because it was, while the Triang camp asked 'how, exactly'.  Rovex's first loco, the Black Princess, was no more underscale and compromised than HD's pacifics, and had a detailed cab while HD's were full of motor; HD had a definite edge with valve gear and wheel/rail profile, but that has nothing to do with the material the loco body is made of.  Both improved over the next decade until there were models that were not bad for the time (if you could live with boiler skirts, solid bogies on diesels, and flangeless centre drivers), like the HD Castle and rebuilt Bullieds, or the Triang Brush Type 2 or Britannia.  

 

It might be assumed that plastic is more prone to breakage than metal in a concrete floor drop accident, but mazak rot sadly means that both materials are vulnerable in this scenario.  In fact, the heavier motor and chassis block of a HD diecast loco might make it more vulnerable depending on which part of the loco lands first.

 

HD, despite the cachet, eventually lost out because they were too slow to introduce 2-rail and abandon 3-rail, and because their production costs had become unmanageable.  Henceforward, it was assumed, for no really good reason, that diecasting was too expensive to be viable and while Wrenn catered to the niche market at a price, there were no die cast locos in the field of mainstream 00 RTR for the best part of 50 years.  In fact, there was a considerable period when Triang, later Triang Hornby, were effectively the only game in town, and it showed!  Poor models from them made certain people yearn for the good old days of diecast HD, reinforcing the idea that diecast was somehow better.  It was sort of 'proper engineering' the sort Britain, dammit Carruthers, was alleged to be best at though by the late 60s and through the 70s and 80s it became apparent that this was a concept as one with the snows of yesteryear, if it was ever true and not just jingoism.

 

Modern tooling methods and the availability of small, cheap, can motors have allowed production engineers to reconsider diecast metal, and their conclusions are clearly that in some cases it is more cost effective than plastic.  Each projected model is considered as a standalone and individual project, and no doubt the shape of the finished product, and the degree of fidelity to the prototype you can achieve within the budget is no doubt a factor, and the reason why some locos are partly diecast and some are all plastic.

 

When the arrival of Lima, Airfix GMR, and Palitoy Mainline onto the scene provided Hornby, as they were now calling themselves, the old Triang, with some competition, the new products were marketed and enthusiastically reviewed as superior.  They rode at the correct height, had flanges on all wheels, daylight visible where it should be in silhouette below the boilers, underframe detail, clear cabs, separate handrails, better liveries and finishing; in that sense they were superior.  But these advantages were achieved at the cost of feeble pancake motors driving through unreliable trains of cog spurs, traction tyres, and Mainline's brave attempt at split chassis, a good idea in theory which dispenses with pickups and the need to maintain and adjust them, was doomed by poor choices of materials, and in this respect they were not as good as HD or pre-pancake Triang Hornby.

 

This has been overcome by using traditional worm and cog drives from can motors which are effectively the modern version of the old open frame types, but a problem remains, that of haulage.  The use of a heavy die cast body may assist slightly here, but it will be a marginal improvement at best; in any case I very much doubt if that is uppermost in the minds of, or even in the minds of, the engineers making the decision at the production planning stage of a loco's development.  Production planning is basically attempting to devise a method of making what the prototypye mockup model has given you into a cost effective and hopefully profitable reality; 'give us 2,000 of those by the agreed date at this cost, we'll be back to pick them up on the agreed date'.  This is all done by contractors, and so long as the commissioners in the UK are happy with the result and we will pay the asking price in sufficient numbers, it's a win win all round.

 

There is no real way of determining if a s/h loco bought sight unseen online is die cast or not unless this is stated in the seller's description.  Recent production, last 15 years or so, can be shown by the presence of NEM couplers, but some Hornby Railroad items still have riveted couplings in current production, it being too costly to retool their chassis for NEM mounts and maintain the low cost that should apply to a redacted model.

Edited April 14, 2020 by The Johnster

[34theletterbetweenB&D]

3 hours ago, alexl102 said:

...are there any/many Bachmann locos which use die-cast metal as part of the model? Is there any way to tell which when buying second hand?

Most of the tender locos have a diecast footplate with the plastic mouldings from which the bulk of the loco body exterior is made screw attached, the Peppercorn pacifics have a diecast cab as well. The exceptions are some all plastic bodied locos which previously had a split chassis mechanism, but are now supplied with a wiper pick up mechanism, their A4 and B1 for example. Post a question about any specific model, and someone will know.

 

Their tank locos follow a fairly standardised construction pattern with a cast body frame onto which plastic mouldings representing all the exterior body work are (largely) screw attached.

[alexl102]

Cheers, both really comprehensive answers which have helped me understand a little better.

 

[34theletterbetweenB&D]

Forgot to post that if you want to sample a Bachmann steam model with a good quantity of metal in the construction, the 9F is the one to go for.