I seem to read frequently that manufacturer X could easily do model Y because they already have say, the boiler, from model Z. Just seen another one today which is "well Dapol could easily do a Class 88 as they already have the moulds for the Class 68."

Am I wrong in thinking it is an illusion to think that things are that simple? My understanding is that there will be different tools/moulds for different materials so, for example, a bogie tool for the "slippery" plastic can be re-used across a range of models. But many of the locomotive bodies are from a single tool so isolating a boiler or a cab is not feasible if the rest of body for a new loco needs to be tooled anyway. OK the CAD will be available for that cab or boiler but creating the new tool is still a costly exercise.

Any experts who can put me right or wrong on this?

I am no expert on this sort of thing, but I suspect you are already right. 

If the original tool is configured to swap parts from the beginning then yes but I doubt many models are built this way.

I would expect that there will be an after market conversion for the class 88.

Hi Mike

Everything you say is right.  You have a variety of options:

- if possible alter existing tooling. May be cheap, but the downside is that you no longer have the original tooling!
- design the tooling to have the relevant slides to produce either variation. Only works if there is enough in common and the slides may be prohibitively expensive.  Plus some manufacturers don't like excessive slides due to risk of join/witness marks
- utilise existing CAD but that doesn't save you much.

Some manufacturers don't even like using common parts across different models as they prefer to keep each project self-contained.

Cheers, Mike

The basis for the molds being the CAD models this part can be quicker/cheaper as less time is required but as Mike said this is relatively minimal in the grand scheme of things. Some variations such as the Class 85 Eleccy's they had two pantographs at one stage and one of these was later replaced with air tanks. This could quite cleverly be covered with minimal changing.

On a side note with the ever increasing popularity and capabilities of 3D printing because there is no mold required they can more easily be created with modifications like those of the 68/88.

Quote
Some manufacturers don't even like using common parts across different models as they prefer to keep each project self-contained.

Not like the Poole Farish steam locos, one chassis fits (almost) all; at least until they brought out the 08, that had a new chassis which with slight differences to slots for axles also served the 4P and IIRC was also modified a bit more for the 8F.

The only noticeable differences were things like coupling or bogie fitting mainly differing for tank or tender locos.

I presume there was a basic mould for casting the chassis block which was then machined to suit either tank or tender loco with coupling or bogie/pony truck mountings.

Had to Google class 88 to see what it is
Jeepers. It's only marginally less ugly than the class 70

The Class 88 is actually slightly longer than the 68, so it would need to be a totally new tooling. It may be a bit to niche at the moment, particularly seeing how precarious the UK market is at the moment.

I was under the impression that the 88 and 68 bodies are the same in terms of size. It's only differences are on the roof and positions/sizes of the grilles on the body sides.

Prepared to be proved wrong.

The rail press seem to think they are the same size.

"The Class 88 was developed from the Class 68 diesel locomotive which is now in service with DRS, and shares the cabs, bodyshell, bogies, control equipment and traction drives. According to Stadler, the UKDual is rated at 4 000 kW in electric mode and 708 kW when using the Euro IIIB-compliant Caterpillar diesel engine. It has a maximum speed of 160 km/h, and can haul a 1 800 tonne freight train under 25 kV electrification before completing its journey in diesel model on an unelectrified route."

Does anyone have the dimensions or drawings?

Quote from: newportnobby on March 28, 2017, 03:31:47 PM
Had to Google class 88 to see what it is
Jeepers. It's only marginally less ugly than the class 70

Have you never seen a Class 68, then? They get around quite a lot and are visually very similar to the 88s (they have identical cabs). I don't think they are ugly, but each to their own.

Agree on the 70, though - now that really is ugly!

It'd make more sense for them to be the same with different internals. I had a look at the Vossloh website though its not obviously detailed the difference...