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Batch building SSM J15s

John M

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Although OO works have produced a rtr J15 the SSM kit is probably the best option short of scratchbuilding for someone who works in 21mm gauge or wants to capture some of the major variations within the class.


I built up a collection of these locos since the kit was released by Terry McDermott in 1985 and gradually improved my skill in building locomotives from kits. The TMD J15 was an ingeniously designed and complex kit when introduced and generally stands up well by present day standards.


My first attempt at building the kit was not the most successful mainly because I did not have the necessary skill or experience. I sucessfully re-built/re worked the chassis several years later, which lead me to build a second J15 which was the winner in the kit built loco category of my local model railway clubs annual competition. Irish broad gauge locos were somewhat rare in Milton Keynes MRC competitions.


I acquired a third (part built) SSM J15 as part of a job lot of TMD/SSM loco kits at a swap meet and later bought a further two kits from Paul Green before SSM changed ownership.


My initial plan was to scrap my original J15 193 saving the tender, boiler, cab and fittings for a scratchbuilt 52 or 60 Class 4-4-0, but eventually decided to retain the loco and build a replacement chassis.



The original locos 193 rebuilt 1994 an early Coey J15 sitting high at the front end, no brake gear and a missing tender spring, 191 assembled 1995 missing tender axleboxes & the "White Engine" another early Coey loco a non runner.


Mechanically the locos demonstrate the evolution of the 4mm drive train.


193 has an Anchorage DS10 with MK2 Sharman 40:1 gearbox and sprung chassis Blacksmith? models axleboxes and Sharman wheels. Driving and tender wheels are shorted one side with pick up through the tender.

With a DS10 motor and 40:1 box 193 is more a racer than a goods loco!



Built nearly 8 years later 191 has a Mashina can motor and a Branchlines slimline gearbox with 80:1 reduction a bit slow for mixed traffic work or the odd excursion train.



The "White Locos" underframe was a bit of a mess. The original owner had attempted to assemble the locos to S4 standards but came unstuck with seized axles and dry soldered joints. Photo was after I removed the hornblocks (early Perseverence)


I decided to build one of the "new locos" as a superheated J15 with heavier mainframes similar to  RPSI 186 and use the spare set of frames as a replacement for the "white locos" underframe.


The new locos would be fitted with High Level Load Hauler gear boxes and Mashima 10X20  locos to bring a bit of standardisation into the fleet :lol: just like the GSR standardisation efforts of the 1930s.




In the end I decided to replace 193s mechanism with frame gearbox and motor salvaged from the white loco. I used framespacers of my own design to replace the original frame spacers and reinforce the chassis in the ashpan area a weak point in the original design.




21mm chassis assembly jig turned up in the Unimat the bolts and springs are from a OO gauge roller gauge :D




Completed main frames reinforcing strips above the rear hornblock cut outs are cribbed from an idea in Iain Rices etched loco construction.


This loco will be fitted with Mashima 10X24 motor and Branchlines gearbox and Sharman wheels similar to 191 which should result in the two locos having a similar speed range and performance.




The "white loco" and the two new locos will be fitted with smaller 10X20 motors and High Level gearboxes and it should be feasible to hide the motor and flywheel in the boiler.





Test set up of motor and gearbox.


I will leave the superstructure and variations built to another day!


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I can only envy your skills John; this to me is engineering in miniature.


Like the great majority of modellers of Irish railways, I use 16.5mm gauge. I am prepared to accept this very large compromise but I do have a difficulty with steam locos. Most Irish engines were relatively small. This, to me, creates the impression of the boiler sitting between the wheels rather than over them. You can I think just about get away with it on tank locos such as the NCC 'Jeeps'.

I have even wondered about trying to represent something like a J15 on 16.5mm track by distorting scale, building the boiler to 3mm scale. But when I sober up, I realise that is getting very silly!


Yes, to model typical Irish steam engines, 21mm gauge is a must.




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One way to get gauge correct is to alter scale to slightly bigger than 3mm/ft. Approximately 1/97 scale. For chassis the original Dapol/Hornby Terrier loco is pretty close to right size. Not sure if moror still fits in, but that can always be fitted in the tender. As scale is still very close to 3mm/ft , many of the 3mm scale accessories(eg figures) can be used as can 15mm wargaming items such as buildings and vehicles.

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I'll surely never model either of them but I've always thought both types of J15 were among the most attractive 0-6-0's.

The picture of 191's chassis I find encouraging., as I'm thinking of using the same gearbox/motor combination in Bishops Castle 'Carlisle'. I wonder if that will be a tighter fit when angling the motor into the boiler while assembling, I suspect the J15 has a rather bigger boiler than Carlisle. Does that fit easily?


Nice models anyway.

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To Simon's suggestion to work to circa 3mm scale on 16.5mm track, I have thought about that at various times in the past but it always struck me as being at least capable of becoming a problem to solve a problem!

In more recent times, I might consider it as an option if I were to build something very specific: say a bit of the Sligo Leitrim or the Waterford-Tramore.

Ultimatly I just have to accept that people like John are much more skilled than I in some areas of the hobby and that I should admire and applaud their work.


I'll get back to "plastic engineering"!




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I will concentrate mainly on the aspects of building the locos to 21mm gauge and the different variations. 5XP wrote an excellent piece in 2010 in assembling the kit in OO gauge. 

Although the kit was originally produced in etched brass with turned brass chimney and dome, the kit was later produced in nickel silver with cast whitemetal fittings.


On the positive side nickel silver is more rigid and easy to solder, the downside is that it is more difficult to form the complex curves in the running board and the waisted section at the bottom of the smokebox.

The other issue is that it is extremely difficult to fold up and drill the brake hangers as the hangers and rigging are very fine, the simplest solution from my point of view was to replace the kit brake gear and reversing gear with new parts of my own design.



One of the challenges in building in 21mm gauge to OO/EM standards is ensuring that the wheels will fit between and inside splashers without fouling at an early stage


NMRA110 & Markits wheels are too wide to fit between the splashers of a J15.




Gibson or Ultrascale EM profile wheels will clear.




One advantage of nickel silver over brass is that I did not need to reinforce the frames above the trailing axle hornblock cut out.




Three sets of loco mainframes. I finally got round to assembling the parts for a superheated J15 I designed in 2012-3? I replaced the SSM frame spacers with turned and tapped spacers of my own design which assist in squaring and lining the mainframes, the chassis for the superheated loco has more conventional fold up frame spacers.




I decided to fit the motor horizontally in the firebox of these locos adding a stiffening plate in the ashpan which will act as a motor mount.


I have decided to fit springing  (continuous beam suspension) in the superheated loco and compensation in the two saturated locos. I find that compensation significantly improves power pick up and smoothness of running with small 4 & 6 coupled kit built locos compared with a rigid chassis in similar locos

Edited by John M
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I decided to model the locos in GSR rather than CIE condition, mainly something a bit different from the CIE era commonly modeler, the greater variety of locos & stock both in terms of greater number of different classes and level of detail variation between individual members of the same class, although all over grey locos seem to have been better turned out and I prefer numberplates to large transfer numerals :)


Stepping a bit ahead but focusing on detail variation.



Line up of locos in the erecting shop.


229 & 1?? waiting for their boilers to be dropped in & the "white engine" now fitted with a new set of frames.


The loco on the left is based on 229 a Coey J15 of 1903 one of the last of the class to be built.

The Coey locos had direct rather than linkage reversers, slightly raised front sandboxes and exposed cab splashers.

I am planning to model the loco with a sloping smokebox and double doors, though I have assembled a conventional smokebox as a spare.

The superheated loco is assembled using a test etch  frames, spectacle plate and smokebox I designed about 5-6 years ago.

It would need to re-design the artwork to produce a production version of the etch to make everything fit/simplify assembly.



I originally acquired the white engine as a part assembled kit  and initially assembled the loco with a direct reversing lever like the 192-199 as the linkage reverser was missing.


I have retrofitted the loco with the linkage reverser a spare from 229 to bring the loco more in line with the majority of the class adding another "standard" j15 similar to 191.


I need to repair/replace the riveted strip at the base of the cab side sheet and improve the fit of the boiler fittings. 193 will probably go in for a rebuild with the re-conditioned frames from the white engine once the three locos on the bench are completed and running.




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  • 1 month later...

I finally got around to assembling the tender superstructure after a 5-6 week hiatus from small scale modelling (clearing and mulching autumn leaves!)


The tender assembly is reasonably straightforward the only significant change was re-locating the rear fixing bolt to clear the trailing tender axle.



I used copperclad sleeper strip to clamp the tender sideframes in place until soldered into position.


Excess solder to be removed from around the sand boxes and tank fronts.



I still need to form the tank filler and fabricate tank top/coal plate.


The kit was originally supplied by TMD in 1985/6 with etched brass parts, turned brass funnel and dome, at some stage SSM re-issued the kit in nickle silver with whitemetal detail castings.




Made a start on cab detailing fitting firedoors to backhead and assembled cab splashers and test fitted backhead.


Quite a bit of tidying up required before final detailing.



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