7mm Doing a Duchess Justice (update/reprint of 2002 GOG Article)

[Cliff Williams]

DOING A DUCHESS JUSTICE
Cliff Williams talks about building another Martin Finney Duchess


46245 City of London - picture courtesy Nigel Burkin BRM

So the time has come, and you hanker after a Duchess to fulfil all your dreams, hopes and expectations.

Then it strikes you that there are kits from at least four manufacturers. So which, if any, has caught the likeness best? How easy is the kit to put together? Which is best - whitemetal, resin or 'flat pack' brass for the boiler/fuebox/smokebox? Is there an affordable, quick to build, sturdy and accurate option for me? Will the loco run well without modifications or correction of design errors?

In reality no kit manufacturer has achieved all of these goals, but one has come close enough for me to be able to build, paint and line an extremely accurate Duchess that runs smoothly. I am sure that many of you will have seen No. 46245 City of London on test tracks at major GOG events. Now, with Nos 6231, 46229 and, 6241, going through the works, it is an exciting time as I get to eat, sleep and breathe Duchesses all over again and again and again. No doubt even more will follow.


Having built Duchess kits by a number of manufacturers, I have found the Martin Finney version to be the easiest option to capture the spirit of these mighty machines. The kit allows you to build the original streamlined locomotives in post-war de-streamlined condition (Nos 6220-29, 6235-48) and the non-streamlined locomotives (Nos 5230-34, 6249-52). The complete kit, less wheels and motor, is not cheap at over £520, but Martin makes no apology for this, describing it as "probably the ultimate 7mm kit to be released to date by any manufacturer".

For this outlay you get a resin firebox/boiler, resin smokebox, brass and nickel silver etches, inside cylinder kit, tender kit, homblock pack, lots of highly detailed lost wax castings, couplings, good quality whitemetal castings, and extensive instructions. If you are going for the deluxe Duchess by adding Alan Harris wheels with prototypical hollow axles and inside crank axle, Diane Carney plates and a Crailcrest motor, the total bill for all the bits will come to well over £1,100.


Martin does tend to design his kits to as near scale as possible; this has put off many in the past as it can cause problems in making the locos run if you are inexperienced in problem solving. I am sure that he doesn't have access to a test track like mine to see how his chassis designs can cope when loaded up with g-forces on corners; if he did then there would more than likely have been a different design for the Duchess compensation.
There is nothing to stop any Finney kit ending up as an accurate, sweet-running loco with a few simple modifications - I have several in my collection. I have even heard of people taking fright with their Duchess kit simply due to the resin boiler, even though the resin section is at least 6mm thick, and selling the kit on untouched.

Well, I have witnessed Martin absolutely belting the living daylights out of a resin boiler against his stand with the noise echoing around the hall, but the boiler showed only minor damage and did not split. You simply couldn't do that to a whitemetal or brass boiler and remain as confident as Martin was. I am still shivering at that sight.

Please read on through the stages of the build - please note this article was first published in 2002 - more recent updates will follow later

 

[Cliff Williams]

The tender

As a personal preference I usually start with the tender so that there is something to admire relatively quickly. The tender kit caters for the non-streamlined version with a flush rear and individual steps, and the de-streamlined version featuring extended sidesheets at the rear, along with rear ladders.


Above: Alternative tender rears possible from the kit

The body superstructure goes together well with a jig to help in forming the tricky curve on the upper sidesheet. In assembling the body I found that very little deviation from the instructions was required.
To reduce cleaning up after soldering-on the whitemetal coalpusher, I developed a method which is definitely not for the faint-hearted but gives lovely clean results, and I now use this whitemetal-to-brass technique extensively.


Above the main components for the tender

Lightly tin the brass area that will be covered up by the casting with first normal then low- melt solder, drop the casting into place with a little flux and then apply a blow torch with a small flame sparingly to a remote area of the brass and as the heat flows through the brass the casting will settle leaving only the most minor tidying up to be done. Now that I've told you this, don't go asking Martin for spares when you ruin them - practise a lot before going for it as this technique may not be for you.

Above: Aerial view of both tenders showing the coal pusher

The tender chassis is a highly detailed item featuring just about everything there is to be had, but with one major design flaw - in my opinion at least.

Build the kit as instructed and the wheels are trapped for life.

Sorry, but this is not good engineering practice. However this can be overcome and Martin simply doesn't know how close he was to a solution when designing the tender kit and writing the instructions. First of all make the brake gear detachable by soldering small brass tube instead of wire into the brake mounting holes in the chassis and trim to length. Tap the tube 14BA and mount the brake hangers with 14BA bolts. The major contribution to this design problem is use of three pairs of frames to make up the chassis: outside detail frames, inside chassis and a 'carrying' frame sandwiched between the two.


Above the chassis with the modifications to allow wheelset removal

The carrying frames are the troublesome ones as they wrap right around the internal chassis enclosing the wheels; they are there to support the real chassis cross- members that are so visible on the prototype yet so rarely modelled. Trim the ends off the carrying frame to allow the outer wheels to be removed. For the centre wheelset remove the lower area of the hornguide so it is U-shaped, then take two 12BA nuts and a bolt and screw the nuts apart by the width of the centre journal.
Quickly solder the nuts to the inside face of the journal and then repeat the process for the other side. This allows you to remove the 12BA bolt and drop the wheels out just like the prototype, but only once the brake gear has been taken off.

Above the chassis from underneath


Above tender components

Can you imagine how much good work would have to be undone if built as advised should the tender require a wheelset overhaul? This is why I feel it is such a big design flaw, which can be overcome with these modifications.

 

[Cliff Williams]

The loco body
Turning to the main guts of the beast, namely the loco, you will find that the firebox/boiler unit is cast in resin with an awful lot of sharp detail already in place, and the same goes for the separate smokebox. The smokebox fits into a rebate in the end of the boiler and should be slightly undersized so it can be moved about. My first two Duchess kits had one tight pair and one slack pair, so check yours carefully. Needless to say a replacement pair was received by return post. To join these two together, first make up the footplate on its platform, then assemble the cab and screw it to the footplate; next offer up the firebox/boiler and mark up for the self-tapping screws to hold it on to the footplate and cab front.


Above the main components for the loco body

The same self-tapping screw procedure should be done for the smokebox; this will align the two units almost automatically. Remove either of the resin units and sparingly apply 24-hour epoxy resin, reaffix the resin unit, adjust/align the join and leave alone for a day. Once set, this will allow the firebox/boiler/smokebox to be a separate unit from the cab and footplate for painting.

I enhance the construction methods further so that there are as many detachable components for the loco body as possible to aid painting and, while this is not strictly necessary, if one can build things in a modular fashion it will be easier later on. For instance, the lost wax brass Silvertown lubricators and all the pipework are best made detachable so all the splashers can be lined without difficulty. This is achieved relatively easily by cleaning up the thread cast on to the stalk of the lubricators and by careful assembly of the pipework.

Above Pipework painted black, this whole section is removable

The 0.3mm copper wire replicating the pipework from the lubricators sprawls all over the splashers and footplate and this can be fun, but is worth the effort if you are as keen as I am to do things right – definitely a test for the sanity. I know Tony Reynalds gave up on the sprawling pipework and simplified his, so it is nice to be able to do something that Tony didn't!

Above Pipework on Duchess of Atholl

Talking of Silvertown lubricators, the cast lids feature raised lettering just like the prototype; simply astounding detail and an example of what makes this kit stand out from the crowd. Other items best
made detachable are the vacuum ejector, smoke deflectors (when required), handrails, whistle and any pipework lying around the splashers.


Above Silvertown Lubricator cover detail

To make life easier, join together the three separate loco fallplates or you will be forever derailing after curves due to the two small side fallplates dropping down between the loco and tender.
Obviously it is best to have the loco completely assembled prior to painting; with care this can be done and still have all these components come off in readiness for painting.

For example the vacuum ejector has a mounting post that goes right into the 6mm wall of the boiler/smokebox. Once the loco is painted and the front boiler band is lined out, simply push the ejector back on to the boiler with a tiny spot of Araldite. This absolutely transforms the finishing of the loco.


Above cab with tipping seats

 

[Cliff Williams]

The chassis
Martin has designed a compensation system involving working hornblocks, a central rocking beam for the front axle, and side equalising beams for the two rear drivers. If you intend to run the loco at speed on anything other than straight track then, quite simply, don't do it.

Having built several Finney Duchesses, this is definitely a disaster for a working loco. Why? Two reasons prompt me to say this. First the overall frame width is 26.7mm and the wheel back-to-back is 29.2mm, allowing an absolutely massive 1.25mm clearance between wheel back and frame - the axle has too much rocking movement in totally the wrong direction, resulting in shorts between the chassis and wheel.

Secondly if you are using the excellent crank axle by Alan Harris for the front drivers, this results in one-third of the loco weight bearing on the centre of the axle between the inside cranks, which is the weakest point of the axle. Many of you will be thinking that 1.25mm doesn't sound much of a clearance, but I can assure you this is all that No 46245 has, and it goes round the Guild test tracks happily. I can also explode the myth of requiring extra sideward movement on the centre drivers, as 46245 and many other engines in my
collection do not have this. So an overall 1.25mm wheel back-to-chassis clearance on each side is quite manageable.

Above the loco chassis, this is under 6231

Do not despair though, as the compensation system that works easily with 1.25mm clearance is set up with 10 BA nuts on the top of each of the hornblocks screwing down on to the square bearing. The ride height is set by screwing the 10BA bolt on to the square bearing allowing vertical drop only and at the same time restricting the fatal side 'seesaw' or rocking movement that Martin has designed for this loco.
This method also ensures better support for the crank axle as the load is now taken closer to the wheel backs and further away from the Iess-strong crank axle. Simple, effective and reliable. With her extensive mileage, City of London is absolute proof of this, and can negotiate 6ft curves with majestic ease.

Above the chassis for 46245

The chassis is designed to be built with units for the cylinders, inside cylinders, lower firebox, brake gear and sand gear combined as one unit, exhaust/live steam injector pipes, valve chest snifting valves and valve gear. A lot of these can be, or need to be, easily removable for future maintenance.
For example, if fixed permanently the large exhaust ejector pipe on the offside will stop removal of the rear Alan Harris wheels, so I just drill and tap the end out for a 12BA bolt where it joins the frame at 90 degrees for easy removal. The Alan Harris front wheels with crank axle are best made removable, and this is easily achieved with the homblock system by bolting the front springs on so they also double up as the keeper plates for the hornblocks.

With the sanding gear attached to the brake gear, the front drivers are removable.

Other basic alterations to make the chassis run relate to the front bogie and trailing truck. The bogie rubbing plates require reducing to a compromise overall width of 41mm, otherwise the plates strike the cylinder draincocks. The bogie guide system with a secondary pivot over the rear bogie axle simply doesn't work.

Instead stick with the conventional system of pivoting over the centre of the bogie. Widen the rear oil 'mudguards' protecting the rear bogie wheels, leaving only a small gap between the slidebars and the mudguards. Extend by at least 2mm the bogie side control stops which are small lost wax castings on the main frames just behind the front bogie wheels.
Remove a square area on each side of the rear frame spacer directly above the trailing truck wheels; failure to do this will result in shorts whenever the loco goes over a hollow. On curves, the front brake cross beam will strike the flanges of the rear bogie wheels, so trim this beam down by a good bit to gain clearance.

 

[Cliff Williams]

Painting
I am one of the few builders who enioys painting and lining the loco as much as building it, hence the design of modular components to make this easier. For LMS/BR red, thanks to Tony and Alan, I now use a combination of cellulose Rover Damask Red and Ford Lacquer red mixed 50:50 and spray painted with an automotive spray gun. Hand lining with a bow pen, PC transfers and a satin lacquer finish my models - and City of London was no exception.

Above - with sandbox brackets fitted later on this has allowed the splashers to be lined out

It takes a couple of weeks to carefully reassemble the forty-odd components without damaging the finish. I simply can't wait to paint my first LMS Duchess with the full gold-vermilion- gold lining as it will be an exciting time getting 6231, alongside the others.

I have yet to see another Finney Duchess running at a Guild event, so hopefully these tips will prompt more to be completed and shown off running at events, as the end result looks every bit like the original locos it is modelled on.

To sum up: all the whitemetal and lost wax castings are absolutely exquisite and a pleasure to work with; the etches are sharp with no dimensional errors; the resin boiler accurately captures the real thing and takes a lot of the work out of the job; the loco chassis compensation design could be better; the loco and tender chassis require tweaking to allow for maintenance; there are no inaccurate components in the kit; and everything else fits.

So is this 'the ultimate 7mm kit released to date?' Probably.

First published GOG Gazette February 2002 & Railway Modeller


Above 6231 Duchess of Atholl painted and lined with gold-vermilion-gold by me

 

[Cliff Williams]

updates for more recent photos

 

[Cliff Williams]

updates for more recent photos to follow

 

[Silverystreaks]

I always go a bit weak in the knees department when I see a BR Red liveried Duchess on my screen, so while I await my own returning from the Paintshops I will be following this thread with much interest

Bob

 

[P A D]

Superb Cliff!
Many thanks for sharing the article on here. I was gob-smacked when I first saw it in the Gazette, but the images look even better on the screen. I look forward to seeing the updates.
Cheers,
Peter

 

[Cliff Williams]

Thanks Peter for the very kind words!

I could not find the original text but then remembered the OCR kit on scanners so got it resurrected that way.
Expect an image fest soon, using the big camera on 46229, 46245 and 6231, t might show up wrinkles but Heyho worth a laugh.

Cliff

 

[Pannier Tank]

46245 City of London was my favourite Duchess. I remember on one occasion she worked a Crewe to Willesden Parcels which stopped at Bletchley to drop off a couple of coaches heading for the Western Region via Oxford. The Trackwork in the "Field Sidings" creaked under her weight and the wheel flanges squealed under her passing. A sight and sound that I've never forgot. Happy Days.

 

[Focalplane]

Sitting in a hotel room in Lyon I now can’t wait to get home to continue my Finney7 46235. I have already finished the tender chassis with wheels in place but I can live with that. Your description of the loco’s suspension comes just in time as I certainly plan to exercise mine on 6ft radii at speed.

As to the colour, my personal preference is everyone else’s antithesis. The BR green to me, pulling a rake of maroon coaches, is perfection personified!

Thank you for posting this, it will be most useful.

Paul

 

[P A D]

Sitting in a hotel room in Lyon I now can’t wait to get home to continue my Finney7 46235. I have already finished the tender chassis with wheels in place but I can live with that. Your description of the loco’s suspension comes just in time as I certainly plan to exercise mine on 6ft radii at speed.

As to the colour, my personal preference is everyone else’s antithesis. The BR green to me, pulling a rake of maroon coaches, is perfection personified!

Thank you for posting this, it will be most useful.

Paul

Hi Paul,
BR Green for me also.
Cheers,
Peter

 

[john lewsey]

Hi Cliff they look stunning

 

[LarryG]

My Sir William Stanier will become City of Salford one fine day...So yes, another green devotee...

 

[Cliff Williams]

We do have a green Duchess in the roster, but a Masterpiece Models one, it took a few tweaks to get it closer to the mark though, I ended up tweaking quite a few of them over the years. If enough interest I might get it on shed for a pic or two.

 

[Rob Pulham]

I am a proper heretic

LMS Red, single chimney, no smoke deflectors when I get around to mine (Duchess of Buccleuch).

 

[Pencarrow]

LMS wartime lined black on Sir William Stanier FRS would be my choice.

 

[LarryG]

It would more correctly be Post-war lined black......"The 1946 Express Passenger Livery"

 

[Pencarrow]

It would more correctly be Post-war lined black......"The 1946 Express Passenger Livery"

Indeed. Although to be fair I've not modelled LMS for 30 years, so the detail has faded somewhat.