K's J3?

[60526]

I'm sure that somebody has looked into this in some detail, but what exactly is the K's J3 or J4? I picked one up on fleebay a long time ago and now that retirement has finally come along I have the time to get on with it. It's had a soaking in Dettol and a hot bath, so it's now in bits, I'm looking to model it close to when they were withdrawn in the 1950's, but I'm slightly confused when comparison is made with photos in Yeadon, to help I will be buying a Isinglass drawing, but which one?
Regards
Charlie

[Atlantic 3279]

I suspect it's a bit of a J "three and a half". As supplied, the parts in the kit that I built produced a boiler of intermediate diameter and a cab of intermediate height.
Then there's the tender, which is possibly only correct for either a loco that passed to the LNER via the M&GN, or a brand-new member of the Ivatt series of these locos before its tender was appropriated for use behind a bigger loco.

[john coffin]

Given when it was designed and made,plus it was almost certainly originally designed to work with a Hornby/Triang style chassis,
so may well not be to scale in wheelbase terms, it is pretty sure to be based on the J3. ie the bigger boiler version of the Stirling
0-6-0's.

Honestly, you will never know for sure, and a drawing will only confuse even more, since you will find it difficult to reconcile
the various differences. John's drawings cover many of the evolutions of the later Stirling-Ivatt designs and based on my
research and reading the various GA's I have, they are quite accurate to the planned builds.

Graeme is quite right it might well be based on those sent to the MGN.


Paul

[Atlantic 3279]

I think it always came with a brass frame set with screw-fit spacers, and seems to have the right wheelbase.

Mine didn't end up looking too bad as a model on its own, How it would look in close proximity to a true-scale version I don't really know. I later re-equipped mine with a LRM Stirling class D tender, making it agree with a photograph of the chosen loco.
https://www.lner.info/forums/viewtopic. ... 69#p119569

[Pebbles]

From memory the GNR Atlantic predated the J3 and so K's were possibly looking to maximise applications for the tender. It was never designed to fit the Triang/Hornby chassis, it came a with punched plain brass and etched coupling rods. Having measured the coupling rods I'm pretty sure that we are dealing with a 7ft 3inch x 8ft 3inch wheelbase. The splashers are clearly overlarge, that said K's didn't do a 20mm wheel with a crank pin. When it comes to the boiler, it suffers from being a one piece.
A two piece boiler - provided the two parts come out of the same cast can be fiddled with. When it comes to one piece boilers there can be a problem, the great temptation to ensure a good casting is to increase the wall thickness. Increasing wall thickness overcomes one issue, but introduces the problem of differential cooling. As an aside I have never come across a SEF K3 that doesn't have a slight dip around the area where the dome sits.
My J3 boiler had different diameters when measured vertically and horizontally. It is possible to regulate this be gentle squeezing in a vice. If the boiler is still undersize then slit it longitudinally along the bottom and gently prise apart. When satisfied with the diameter hard solder along the gap and smooth off. If you try this - and I have - best of luck!

[60526]

Thanks for the feedback. Yes the chassis is punched plain brass with screw fit spacers, it measures 33 x 29 centres, 8'-3" x 7'-3" so spot on, not sure about hole(s) vertical alignment though. The boiler varies from 19.8 to 20.8mm so a slight bit of adjustment needed there. The wheels are 21mm 16 spoke K's, should be 5'-1½" diameter so slightly over sized, I'm going to modify the chassis to incorporate an equalising beam, the wheels are already close to the whitemetal running plate so will have to make a judgement later. I notice that Alan Gibson can do a milled brass chassis for a J4, but I shouldn’t really be lazy having bought a Proxxon small drill stand and a combination table a while ago, about time I started making use of them.
The tender does not match the J3 photos, but does against a few J2 loco tender photos. The tender wheel centres are 33 x 29, no way of telling if that is right, it also has a cut out at the top front of the side sheets but the beading carries on around from the top and down the front of the side sheets, so probably an earlier tender but I think that it can be modified to 1950’s appearance. The chimney is too tall, dome is not far off but needs a drawing to compare it. The smokebox door is underwhelming and really needs replacing, safety valves look ok but no sign of the cab roof mounted whistle. It has a firebox backhead but it has been cut about probably to cater for the motor that came with it. Need to check on the cab height, the J3 was 6" higher than the J4?
Its 2021 so modelling a J3 should perhaps be down the London Road route, but at £123 not including wheels, gearbox or motor it's just a bit too far at the moment while I get used to being retired, as much as I would like to buy a new Hornby A2 at £170, I see it as a premium price but the colour has put me off, so I've one of Graeme's conversions to be getting on with and I'm quite happy with that. I've also got a K's 2003 Lord President that needs some TLC, it's not 1950's so is pending a decision? But then the J3's finished at the end of 53 and I'm modelling 58-62, but they are cute little engines though. I'll contact Isinglass and see what drawing they advise to use.

[john coffin]

If your measuring of the tender wheelbase is correct, it is definitely NOT a scale GNR tender
it would either be 26+26, 28+24

Paul

[Woodcock29]

I used a Mainly Trains scale J52 chassis in my Ks J3. The wheelbase is the same as the J3. Still available from Wizard I think.
Andrew

[Pebbles]

Well of course the tender wheelbase could be 26mm x 26mm or 28mm x 24mm or indeed 27.5mm x 23.5mm. Having measured my K's tender wheelbase I make it 27.5mm x 23mm. Others may know better but, I from memory I was told that K's would make replacement moulds from existing castings; not really a good idea as casting vary in size depending on the temperature of the mould. This is why Dave Ellis only uses parts from the same throw.

[Pebbles]

Sorry correction alternative wheelbase 27.5mm x 24.5mm total 52mm.

[60526]

Ok, thanks again for the feedback, TW has made a LRM J3 on the dark side which is very nice. Just a bit of feedback, the Isinglass drawing is 436-B based on possible locos 65125 and 32 which were series 315 rebuilds and 65140 and 41 which were series 343 rebuilds.
Here's a photo of the tender.

[Atlantic 3279]

Did you actually mean a measured 23 x 29 for the tender wheelbase, where you originally typed 33 x 29? That smaller dimension would put the model within spitting distance of the 24 x 28 which would be correct for the later versions of the class B tenders, even if a class B would be rare / unlikely behind most J3s. Small changes to the front termination of the coal rails, elimination of the suggestion of top-front corner hand grip cut-outs, and a careful look at the shapes and positions of front coalplate, tool boxes and tank breathers would make it pass for a type A, which might be more likely for a J3, if memory serves on all counts.

[60526]

The mind must have been wandering, I think a pint of Black Sheep was on the menu, I repeated the dimensions wrongly. 33 x 29 is for the loco chassis and 27.5 x 23.5 for the tender,

[Pebbles]

I have been toying with the idea of cutting out the centre springs half way between the leading and trailing springs and switching sides. With a bit of care you could end up with a 6'6" X 6'6" underframe.

[Atlantic 3279]

I did more or less the same thing with plastic Bachmann GS 4200 gal tender underframes in order to produce the 4700 gallon tender for a P1 and a set of frames for a GN tender with equally divided wheelbase.