I've had an idea, not sure of it's a brain storm or a brain fart.

How many scratch builders or kit builders would be interested in a 4-4-0 chassis with a tender drive for around £45 - £50, OR if a kit manufacturer would you produce kits to fit such a chassis.

Main suggestions are for 2 basic chassis with 9' and 10' wheel spacing (or one chassis with axle slots for both spacings) pair of drivers and 9' or 10' coupling rods, Wheels choice of 3 sizes 5'6", 6' and 6'6"  bogie(s) with choice of 2 (or more?) spacings, and 2'6" or 3'6" wheels 6 wheel tender drive, wheel sizes/spacings to be decided, maybe an "add on" pair of wheels for 8 wheelers.

The wheel sizes and spacings obviously don't cover every 4-4-0, however to make this a viable proposition there has to be some limit on the variables, the figures I have chosen are open to debate, but I think that what I have listed should cover most needs,  and assuming that */-  6" scale  0.5mm  is acceptable.

If you are doing tender drive then the wheel spacing is basically irrelevant on the loco side. You can just 3D print or produce a simple folding etch for any loco wheelbase you like. Driving wheel diameter is more of a question and how you attach the rods.

If I was doing an inside cylinder tender loco (which is probably all that is wise with tender drive ?) then the bits I would care about are

- tender drive mechanism - preferably much lower than the Union Mills one. 7'6 spacing and also clear between the wheels underneath would also rock (ha!). Ideally narrow enough that you can have 1mm thick walls around for the body. Even better with adjustable wheelbase by changing the worm/driveshaft bits.

- wheels for the loco

- possibly a standard pre-built 2 and 4 wheel truck frame

- reliable supply

The loco chassis is trivial to do as part of the loco design as is the tender top.

The supply aspect is an important one. It's currently pointless doing kits for the ndrive-productions loco chassis for example because they are made to order with a 9 month backlog!

It would certainly be an enabler for 3D print bodies the same way that the various plastic bogies are wonderful for coach and wagons as most designs are hard to do in 3D print with current wheels. (12.25mm axles/wheels would also be wonderful which is another story and maybe a cheaper one - I am investigating).

(Be very afraid I've just put the test CAD for possibly the ugliest British bogie: the 9' Warner double frame on Shapeways to try...)

Anyway yes I think it would be a useful project but the wheels are actually probably the most important bit - quite a few locos could be done with Union Mills drives for example.

Why are you thinking of asking Mr Jones for prices ?

QuoteAnyway yes I think it would be a useful project but the wheels are actually probably the most important bit - quite a few locos could be done with Union Mills drives for example.

The chassis would include wheels, (sizes as in original post)

I've had a few further thoughts, if the chassis were included as part of a kit, the kit manufacturer could probably include a bogie or pony truck, In that case a chassis would only need to be a basic block with fixing holes, axle slots at 9' or 10' spacing, wheels, coupling rods and keeper plate, plus a tender drive.

I've added an option to the poll,  could you indicate if including the chassis as part of a kit would be a dedciding factor

What about just doing the tender (various wheel configs of course) which can be used for any scratch build tender driven model?

A basic block with fixing holes doesn't really work. You really want the area between the wheels actually matching the underneath profile of the loco ashpan etc. It may actually be easier just to provide the wheels and maybe con-rods (that also means any spacing is possible)

There is a certain "ease of building" advantage to a block with the wheels (and perhaps shaped to minimise the amount of visible block low down) so its a trade off.

Alan

Zwilnik, Union Mills sell their tender drive as a separate item for £25, admitedly only one wheelbase, although as the centre axle is not driven it is possible to shift it either way,  I believe some of the earlier LNER ones were not equal spacing. I have also used them with an additional pair of wheels for SR Urie 8 wheelers

QuoteYou really want the area between the wheels actually matching the underneath profile of the loco ashpan etc. <SNIP>
There is a certain "ease of building" advantage to a block with the wheels (and perhaps shaped to minimise the amount of visible block low down) so its a trade off.

Ease of building is one of the aims of this idea, look at the majority of locos available and the bottom of the chassis block is level to cope with a keeper plate. If people can run Poole Farish steamers then a kit to similar standards should stand a chance, most of the detail on more recent locos is part of a plastic keeper plate, Chance for a 3D printer user to produce enhancements?

I was prompted to some extent by this thread
http://www.ngaugeforum.co.uk/SMFN/index.php?topic=16394.0
One aim is to help people trying to build locos. by making things a bit more straight forward and also trying to reduce initial outlay. Most N kits use chassis from RTR locos which usually means buying  a complete loco, often chancing second hand. New Steam locos start at about £70+ up to well over £100; good second hand ones usually half to two thirds new prices, plus you pay for a loco and tender body you don't need.

The reason for choosing a 4 coupled chassis is that there are so few RTR ones compared to the number that were in service even in BR days. There's no reason why if this does become a reality then other chassis 6, 8 or 10 coupled could result.

Quote from: Dorsetmike on September 13, 2013, 11:27:39 AM
Zwilnik, Union Mills sell their tender drive as a separate item for £25, admitedly only one wheelbase, although as the centre axle is not driven it is possible to shift it either way,  I believe some of the earlier LNER ones were not equal spacing. I have also used them with an additional pair of wheels for SR Urie 8 wheelers

For me the big problem with the tender drive is that its quite big. Fantastic piece of simple and elegant design but quite large, in particular heightwise. That worries me a bit as so many 4-4-0 and similar locos actually had very low tenders. (All the best ones of course also have outside frames  )

Alan

These both use UM drives, the K10 has a hacked Langley body, the A12 has a Worsley Works Caley Drummond Jumbo tender

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Maybe a full load of coal but the bodies are not as high as the UM Drummond supplied with the 700 & T9, the K10 having a white metal body does pull quite a bit better than the etched one.

Do you have any positive comments? I do appreciate constructive criticism.

Mike,

With the apparent demise of the days when Farish would offer their chassis units as spare items, I think that this is a fantastic idea! Most certainly I can think of a few locomotives off the top of my head that would benefit from this!

Oh don't get me wrong - I think its a fantastic mechanism until you want to build say a Dean Goods..

Quote from: EtchedPixels on September 13, 2013, 04:25:06 PM
Oh don't get me wrong - I think its a fantastic mechanism until you want to build say a Dean Goods..

Why would you want to build a Dean Goods!? 

Quote from: Dorsetmike on September 13, 2013, 02:14:28 PM
Do you have any positive comments? I do appreciate constructive criticism.

Mike, I think this whole thing is a great idea. I'd like to see it offered as an 0-6-0 as well to give a really complete range of choices...

Quote from: Gooner1953 on September 13, 2013, 04:54:29 PMMike, I think this whole thing is a great idea. I'd like to see it offered as an 0-6-0 as well to give a really complete range of choices...

Seconded on the 0-6-0 option!

Quote from: Atso on September 13, 2013, 04:27:48 PM

Quote from: EtchedPixels on September 13, 2013, 04:25:06 PM
Oh don't get me wrong - I think its a fantastic mechanism until you want to build say a Dean Goods..

Why would you want to build a Dean Goods!? 

They got a lot of places including Welwyn Garden City (as WD199) and why not given LNER F4's got to St Austell and Wadebridge during WW2 running armoured patrol trains.