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 David No. 58 - Hudswell Clarke 0-6-0DM

A 7mm scale (O Gauge) model of a 0-6-0 diesel mechanical locomotive with jackshaft drive built by Hudswell Clarke of Leeds in 1958 for the National Coal Board and delivered to the Cadeby Colliery, Conisburgh near Rotherham, Yorkshire. It was later transferred to the nearby Elsecar Main Barnsley and New Stubbin Colliery but was scrapped in 1986, by Booths of Rotherham or Hartwood Exports, when the colliery closed.  (Further details of the prototype locomotive and the diesel engine)

Hudswell Clarke 0-6-0 diesel mechanical locomotive 7mm scale 0 gauge by David L O Smith 

HUDSWELL and headlight - Hudswell Clarke 0-6-0DM 7mm scale 0 gauge Contents
Wheels Frames Air tanks Cab interior
Louvres Sandboxes Livery Suspension
Rear cabsheet Handrail knobs Registration, builders plates Alternative wheels
Radiator grille Nameplates Flycranks Lights
Buffer planks Ladder Fuel tank shade History
Brake gear Battery boxes Roof  
Brake cross-shaft Horn Buffer planks  

I decided to build this model (even though I would not normally show much interest in diesels, other than old shunters) because my wife bought me one of the nameplates from the prototype as a birthday present a few years ago.  I always look upon even the best of kits as an aid to scratch-building, recognising that some kits are more of an aid than others and that some are of no aid at all.  The Mercian Model Rail kit DL 3 is certainly an aid and a good starting point, and Trevor Cousens is a very helpful chap, a real gentleman (so if you have any issues with his kits, do speak to him first), who put together a suitable kit for me.  

David No. 58 Nameplate from Hudswell Clarke 0-6-0DM 

In summary, I fitted Slater's wheels and a Fine Scale Brass motor/gearbox but I also made a fair number of scratch-built additional and replacement components, including flycranks, air cylinders and sandboxes, that I describe here.

With a view to potentially helping others, rather than give a blow-by-blow account, I thought that it would be helpful to point out some of the ‘sharks’ in this kit that might bite you if you are unaware; I am quite eagle-eyed when it comes to this sort of thing but two still got me and I just had to put up with one and concoct a less than ideal work-around for the other but I could have avoided both had I known about them earlier.  

The instructions in the kit refer to Slater’s wheels (Ref. 7802/02 but I think that this is a typo as it should probably be 7842/02, which appears in the list of ‘Parts required for motorising’ at the end; Ref. 7802 is a set of crankpins) which are 3' 6" diameter 10 spoke crankpin between spokes (intended for BR Class 02) but …  

Spokes milled for the balance weight 7mm 0 gauge locomotive 
No. 1  

… after I had already made some balance weights and machined out part of some of the spokes to receive them (to the right is an example from another loco), I discovered that the wheels should be 3’ 0” in diameter 10 spoke crankpin inline. (OK, yes, I know, I should have done more research beforehand but it’s the part I like the least).
Slater’s Ref. 7839I 3' 3" diameter 10 spoke crankpin between spokes (intended for Hudswell Clarke) would have been a better bet. To start again, to have made smaller wheels and to have rearranged the suspension to suit was more than I could be troubled with so 3’ 6” diameter wheels it has – but it certainly does look wrong.   

Flycrank and wheels for 7mm Hudwell Clarke 0-6-0DM by David L O Smith 

Louver pallens on Hudswell Clarke 0-6-0DM - 7mm scale 0 gauge
The kit that Trevor put together for me had a fret of etched overlays for bonnet doors that should have allowed for the rear two doors to have louvered panels but …  
No. 2  

 … of the four overlays, there were three left hand doors and but only one right hand door. Looking at photographs of completed models, the builders chose to fit one of the right hand doors upside down (ie with the louvre openings pointing upwards) but I decided to correct this by cutting out the louvered panel from each of the overlays, carefully opening up a suitable hole in each of the door impressions that are etched into the bonnet and soldering in an overlay. Actually, making a virtue out of a necessity, I think these panels look more realistic (cruel enlargement to the left).
Looking at photographs of the prototype and comparing them with the etchings of the kit, I noticed that the spectacles in the rear cab sheet were too far inboard. Whilst I was contemplating if this would be acceptable or if I should make a replacement cab sheet, I realised that …    
No. 3  

… the cab sheet was not symmetrical but that one spectacle hole was further from the side than the other, by a full millimetre (right).
Hudswell Clarke rear light on 7mm 0 gauge diesel mechanical locomotive  So, the decision was easily taken and I made a replacement rear cab sheet with the spectacle holes at the correct distance. I machined up some spectacles and soldered them in.  

I made the rear lamp housing from scratch and I later fitted it with a LED.

As I build my models, I think about how I am going to paint and line them so I tend to make them in modules that may be screwed together after all the ‘decoration’ is finished (it amuses me to read some kit instructions that would have you solder everything together and then, as a last instruction, say ‘now all you have to do is paint it’ – Hmm, professional painters do have words to say about this).

To this end, my plan was to make the bonnet, cab and running plate as three separate modules with the bonnet being neatly located over the upturned flanges on the running plate. To support the bonnet, there are formers to be inserted inside and at the rear end (against the front cab sheet); the front of the bonnet is supported by the curved radiator grille. The formers were a good match to the upturned flanges but the radiator grille … Radiator grill and bonnet Hudswell Clarke diesel mechanical
No. 4  

… was etched to the same profile as the formers without any allowance for its being curved, so it was too narrow. My solution was to use one of the alternative grilles (with two headlight openings) as a former just inside of the front of the bonnet and to fit the desired grille in front, ‘making good’ the surrounding gap with a piece of shaped copper wire. Although this looks plausible enough, it is not correct as the corner on the prototypes are clean and sharp.
Front buffer beam Hudswell Clarke 0-6-0 diesel mechanical The whitemetal castings included in the kit for the buffers and chimney were very good, requiring only a little cleaning up, but those for the buffer planks (buffer beams? I don’t know what they are called on a diesel loco) were much smaller than the brass overlays and so they could not be used. I decided to use the overlays, epoxy glue them to aluminium sheets and to cut them out. The rivets/bolts are half etched in the overlays but, when I came to punch them out …

… the half etched depressions were not symmetrical from side to side, they were not in line and their shapes were far from circular and they were of different sizes (they gave the impression of the original artwork having been sketched in free-hand). I decide to ignore the half etches, glue on the overlays and then to drill the front faces for the insertion of pieces of brass wire. With some trial fitting, I discovered that the buffer planks were also too short (would probably have been acceptable with 3’ 0” diameter wheels) so I added some lower extensions in styrene (pinned and glued). If I were to tackle this exercise again, I would make completely new buffer planks from suitably thick brass or aluminium sheet.
The problem of free-hand misshapen and misplaced half etched rivet depressions occurred in other places, although mostly they were quite acceptable. The other notably poor example was the horizontal strapping along the bonnet (above the louvres, below the horizontal hand rails); in this case, I chose to use my milling machine to drill shallow blind holes into the back of the bonnet etch so that I could punch them at the correct spacing in the right place – fortunately, only one hole came half in and half out of a misplaced half etched depression.
Bonnet handrails on Hudswell Clarke 0-6-0DM in 7mm scale 0 gauge
Turning to the brake gear, rather than the typical etched brake hangers-cum-shoes soldered to a piece of wire between the frames and another between the bottom of the hangers, I prefer to make the hangers, shoes and rods as a demountable assembly that springs into place on a set of decent looking brackets soldered to the frames. This is not intended as a criticism of the kit, merely an improvement that I chose to undertake; I reused the etched hangers but I machined up a set of shoes in plastic.
Brake assembly - Hudswell Calrke 0-6-0DM
All fitted up nicely to the wheels (note the balance weights and the replacement, larger bosses fitted to the Slater’s wheels, below) but then I discovered a problem with the brake cross-shaft …
Hudswell Clarke 0-6-0DM wheels and brakes
No. 6 

… the bracket for the brake cross-shaft (transfers the motion from the handbrake standard and air brake cylinder to the brake rods) that is etched into the frames is rather too long so that the brake rods would droop down to their short cranks. I decided to make an ‘overlay’ for a shorter bracket (looks rather neater anyway) and to fudge the short cranks with just two small pulley-like turnings as a representation of very small cranks.
Brake cross-shaft Hudswell Clarke 0-6-0DM
Many kits are designed with their frames a tad on the narrow side, presumably to allow for coarsescale wheels and sturdy axle boxes but, where I am able, I modify the frame spacers with a cut-and-shut (or I make replacements) to push the dimension over the outside of the frames to 28.0mm and to leave a pleasingly small gap between wheels and frame. This was an easy exercise with this kit and it did not lead to any knock-on effects as it might with other models (location of cylinders, motion brackets and sandboxes, for example).
Frames for Hudswell Clarke 0-6-0DM in 7mm 0 gauge by David L O Smith
Sandbox detail Hudswell Clarke 0-6-0DM However, even with my widened frames, I found that when I came to address fitting the sandboxes …
No. 7  

… the sandboxes were far too thin to fit in line with the wheels and they each needed to be packed out with a spacer; OK, this was not a big job and not really a serious shark but it was the last one.

Moving on to my chosen mods:

Handrail knobs – The knobs supplied with the kit are the traditional rounded variety that we all know so well but these Hudswell Clarke locos, like some/most of the Hunslet ‘Austerities’, had very plain knobs, merely a cylinder with a cross hole.  These knobs are available commercially (Markits - M7HRKWDs) but they are easy enough to make with suitable tackle. Hudswell Clarke plain handrail knobs on 0-6-0DM
David No. 58 Nameplate - Hudswell Clarke 0-6-0DM Nameplates – Although I have etched plates for myself before, I ordered these from Narrow Planet, who were happy to work from my photo. I was delighted with the result for an incredibly reasonable charge.
Ladder – Etchings are provided in the kit for the sides of the ladder but they were a bit over-scale and the holes for the rungs were a bit irregular so I decided to make new sides from nickel silver strip and to silver solder on the curved top to one of them. I used the etch as guide to marking out the curved extension but it needed a bit of thinning down and shaping to suit. I temporarily soldered the two sides together and then drilled the holes for the rungs on my milling machine, thus ensuring that the spacing was even and correct. Ladder - Hudswell Clarke 0-6-0DM
Location of ladder on Hudswell Clarke 0-6-0 diesel mechanical I pinned the ladder to the bonnet and running plate and it is hooked onto the handrail (makes for far easier painting and lining).
Toolboxes/Battery boxes – Etches are provided for one 'toolbox' but David No.58 had two, one through each side of the running plate. For me, it was easiest to mill upper and lower sections (from aluminium, because I had some suitable stock material) and screw them together through the running plate. Although the item is referred to as a toolbox in the instructions and elsewhere, it is more likely that they are battery boxes; anybody know for certain? Battery box - Hudswell Clarke 0-6-0DM
Air horn on Hudswell Clarke 0-6-0DM 7mm scale 0 gauge Horn – The brass casting for the horn was not up to the standard of the whitemetal castings for the buffers, chimney and sandboxes but it was a pleasant little turning job to make a replacement and the mounting bracket (not visible in the photo) needs to be made, anyway.
Air tanks – Similarly, the whitemetal castings for the two air tanks were rather poor in comparison to the other castings but I easily made replacements from brass. As an aid to painting and lining, I arranged for the tanks to be mounted on brackets that support the steps to the cab and which are screwed to the frames. Air tanks on Hudswell Clarke 0-6-0DM David No. 58 7mm scale 0 gauge
Hudswell Clarke green livery
Livery – From asking around, it seems that Hudswell Clarke described their ‘standard’ livery as Light Brunswick Green, sometimes referred to as ‘garden shed door green’, and that the best match would likely be LNER Darlington Green, which is believed to be very close to NER Green. I used Phoenix Precision Paints P51 - L.N.E.R. Loco' Green (Darlington Shade). I lined with gloss grey (Humbrol No. 40 Pale Grey Gloss) for the prototype’s white lining, edged in black (Humbrol 21 Black Gloss) with a lining pen and filled in with a brush (Humbrol 85 Coal Black Satin).  I finished off with erstwhile Floquil Flat Finish.
BR registration plate and Hundswell Clarke builders' plate on 0-6-0DM Registration and builders’ plates – The BR registration plates are a standard offering from Narrow Planet and the builders’ plates are a pair selected from the etch supplied with my RTR Hudswell Clarke 0-6-0ST from Ixion Model Railways (I hadn’t use any of them because they were not visible on GCR Humber, which worked in the Immingham Docks; they may have been inside the cab).
Flycranks – Etches are supplied in the kit to make laminated flycranks but I choose to make my own. As I have done this several times before, I was in familiar territory.

The image (right) illustrates milling a more involved embryo flycrank  beginning to emerge during a milling operation; this one is for a Barclay 06 class loco flycrank that I machined up for a fellow 7mm modeller.
Milling flycranks
Flycranks - Hudswell Clarke 0-6-0DM

The flycranks are a force-fit on half shafts (above) that are joined with a muff that fits between the frames (below) to retain the cranks and jackshaft.

Muff, half-shafts and flycrank - Hudswell Clarke 0-6-0 diesel mechanical 7mm 0 gauge

Fuel tank shade, roof and cab - Hudsswell Clarke 0-6-0DM Fuel tank shade – At least, I assume that this is what it is. The etch in the kit was ‘full thickness’ but that seemed a bit hefty to me so I made a replacement out of 10 thou brass shim stock and put the stand-off pillars in the correct places according to the photos of the prototype. I also turned up a filler cap and arranged to secure the assembly by screwing into this from inside the bonnet (after all the painting and lining was complete).

Roof – I elected to add some brass angle as rainstrips to disguise the joint between the turned over cab side sheets and the roof, which slides in under them.
Buffer planks - In building most 7mm scale models, it is normal and expedient to attach the buffer planks to the body/running plate but it made more sense in this case to attach the assemblies to the frames. Hudswell Clarke - attachment of buffer plank
I let dowels/pins into the back of the buffer planks, to locate them most precisely on the end frame stretchers, and then let in 10BA studs to retain them. To help locate nuts on studs in awkward places such as this (the studs that retain cylinders are a more typical example), I turn down to core diameter the first mm or so of the stud so that the nut is well located and lined up before it is turned to engage the thread. Hudswell Clarke - buffer plank
Hudswell Clarke 0-6-0DM cab windows and doors Cab interior – No interior details for the cab are provided in the kit but, to be fair, it would be difficult to see inside with the doors closed; dirty windows would ensure that no detail was needed. However, I do not weather my models and I use real glass in the windows (cut from microscope slider cover slips with a carbide tipped scriber that was originally intended for scratching a car registration number into the window glass) so I positioned both cab doors open.
As I enjoy reproducing the ‘boiler backhead’ and other cab details on a model of a steam locomotive, I made an attempt to model a representation of some of the controls, based rather loosely on a photograph of the interior of a different Hudswell Clarke shunter and using up some parts in my salvage bin. Hudswell Clarke 0-6-0DM cab interior

After all the work, there are relatively few assemblies for the body to bring together after painting and lining, most are screwed together but a few small items are glued with epoxy resin (eg seats, window glasses and ladder, not shown in the photograph, below).

Hudswell Clarke 0-6-0DM component parts 7mm 0 gauge

Suspension – The frames in the kit are designed for a ‘rigid 0-6-0 chassis’ but I fretted out the axle bearing holes to be inverted U-shapes and then I closed them at the bottom with hornstays for CSB (continuous springy beam) suspension. Although I have not used it before, it does seem to be effective.

Slater's vs Walsall 7mm wheels
Wheels by Slater's (left) and Walsall Wheels
Source: Mercian Model Rail

Walsall vs Slater's 7mm wheels
Wheels by Walsall Wheels (left) and Slater's
Source: Mercian Model Rail
Alternative wheels – I had inadvertently used Slater’s wheels that are much too large in diameter but, with the modifications to the hub area that I made, they look acceptable otherwise. However, in the instructions and on the Mercian Model Rail website, is mentioned that “Milled cranks available to suit Walsall Wheels”. The latter are shown on the Accessories page, where there is a visual comparison of the wheels by Slater’s and by Walsall Model Industries (left) so this might be worth considering, particularly if you would rather have milled flycranks, rather than make up the etches in the kit (for possibly the incorrect size of crank throw for your chosen wheels).


Husdwell Clarke 0-6-0DM - 7mm model by David L O Smith

Lights - I fitted 3mm diameter yellow LEDs as head and rear lamps, although I had to machine the rear one down in length and in diameter to allow it to fit inside the lamp housing. A good friend, knowledgeable in all things electronic, kindly knocked out a circuit for me with a bridge rectifier, voltage regulator and a 0.47F capacitor that keep the lights on for a good ten minutes, once lit by the initial movement of the loco.

Headlight - Hudswell Clarke 0-6-0DM Rear light - Hudswell Clarke 0-6-0DM

A weekend away - Although I was working on the HMRS stand at the Warley National Model Railway Exhibition (held annually at the NEC Birmingham), I also belong to the LOGGIES and I was delighted to be invited to bring my model to run on their layout, Central Works, which was exhibited there in 2018.

Hudswell Clarke 0-6-0DM on Central Works  Hudswell Clarke 0-6-0DM on Central Works 
David No. 58 propels 16T minerals to the coal tippler 

History and background - David No. 58 was built by Hudswell Clarke (Works number D1128 of 1958), new to NCB Cadeby Colliery Conisburgh near Rotherham, later to NCB Elsecar Main Barnsley and New Stubbin Colliery Rotherham. However, according to Ron Redman (The Railway Foundry Leeds Hudswell Clarke & Co. Ltd. The Diesel Era) HC D1128 was new to NCB Elsecar Main 29/10/58.

The loco had a 204HP Gardner engine (an 8L3). The mechanical transmission, using a scoop control fluid coupling and three-speed Power-flow SSS (synchro-self-shifting) gearbox, was a Hudswell Clarke speciality (so although this loco is usually referred to as 0-6-0DM it did not have a conventional mechanical transmission).​  

By 1985, David No. 58 was awaiting the fitting of new fluid coupling in its transmission because it had been damaged by being left ticking over with the coupling (scoop) left in the drive position. A replacement fluid coupling was obtained and was placed on the shed floor next to the loco but the repair was never undertaken. The loco was scrapped in 1986, by Booths of Rotherham or Hartwood Exports, when Cadeby Colliery closed. The8L3 Gardner engines from these old Hudswell Clarke locos were a prized item with scrap merchants and Hartwood Exports sent them to China for use in junks. (I love the idea that the Gardener engine from David No. 58 might have seen a new life on the water in the Far East … and still be going.)​

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