G-Train Locomotive Works / Graeme King Joint Venture - GCR/LNER 4-6-0s - B3/1 & B7 available; B3/2 in progress

[Atlantic 3279]

Side view; not much crosses my mind about this at present, save to say that I gather that a minor alteration was made for the production versions of the etches in order to better match up the top rear corner of the cab sidesheet to what is evident in photographs, rather than the slightly different geometry that was evident on the works drawing in the Johnson book.

[Atlantic 3279]

Cab interior with probable backhead master in place. Internal cab splashers are a feature of the final versions of the etches but are conspicuously omitted from this trial build of the test etches. The backhead is an attempt at a GC pattern, but was not originally for a B3 in particular, nor a B7, so fanatical inspection and comparison of pipework, valves, gauges and minute detail of the firebox door will reveal discrepancies. I've extended the lower edges of it so that it should include enough material to now suit large or small wheeled large-boiler GC 4-6-0s. It will need trimming to fit in each case. There's a basic representation of the screw reverser on the right side, as you'll see. Those who like ultra-detailed cab interiors may choose to go one-better and make a separate screw reverser, although on these locos the item was mounted well-forward in the can anyway, so the gain in appearance may be quite small. Older Robinson locos such as the B4s, O4s, Q4s and J11s had their reversers mounted much further back in the cab, and with the original type of cab with side cut-outs the reversers were very visible in some photos, hence I've felt compelled to spend time making models of the reverser for my models of those locos. I think I may favour the lazier approach if and when I build my own B3.

[Woodcock29]

Hi Graeme

A comment if I may. The dome you have used appears to me to be in between the height of the original GC dome and the later lower dome. I haven't managed to work out exactly when Valour got the lower dome but I suspect it was in the early 30s. Yeadon suggests the lower domes were the result of boiler exchange with B7s. Yeadon also comments that the last use of an original boiler was on 6166 in Feb 1933 and this already had a low dome. So any proposed model to be built for mid-late 30s should definitely have a low dome.

I know I didn't get the dome quite right on my model of Valour pictured a few days ago. I was trying to replicate the low dome. For my B8 I have acquired a PDK dome from their D11 kit. Likewise a chimney. Both of these appear to be very suitable.

Hope this is of assistance.

Regards

Andrew

[Atlantic 3279]

In order to resist any tendency for boilers to go out of shape if subjected to too much warmth or pressure (and who knows what might happen if these things are sent by post or are left in somebody's maturing pile for years) the intention is that all boilers will be produced fully circular throughout their lengths. The lower firebox sides needed for those boilers that are destined for small-wheeled locos will be present in every case. Guidelines will be provided on the trimming of boilers to fit the loco. In the case of anybody building a B3 in OO gauge, a large part of the lower firebox (to a line outside of the moulded-on lower sides) and of the lower part of the boiler barrel will have to be trimmed away in order to clear the wheel tops. P4 builders may not have to trim the boiler to anything like the same extent, unless they want clearance for a fat motor. Everybody of course is likely to need to trim away the material between the lower firebox sides in order to get a motor of some sort into the loco.

As a means of establishing the correct characteristics for a master boiler, I had to trim back the width of the splasher tops by about 1mm in each case in order to get the basis 24mm diameter boiler barrel to sit down at the correct level. Access for the necessary filing wasn't ideal, but it was possible. One of the most awkward aspects was the filing of the inner face of the extension cover for the reverser, which sits on the right hand side splasher just in front of the cab. Builders of subsequent locos may find it useful to get the boiler fitting as it should before adding that reverser cover.

As a possibly easier alternative to the filing back of the splasher tops to allow the boiler to sit between, the resin copies of the boiler could instead be trimmed by builders so as to sit neatly on the splasher tops. It all depends on which result you think can be achieved most readily and neatly...

[Atlantic 3279]

Once the latest coat of primer on the boiler is really hard and has had any remaining defects rectified, I can move on to the addition of the plugs in the firebox sides, the blisters on the shoulders, a single step on the smokebox front, and some faintly discernible flat-surfaced cladding bands. I don't want to upset and professional painters by providing bands that are too heavy, or that are too narrow or are uneven or are round-topped so that lining won't sit on them properly! A separate resin snifting valve is a possibility, but I think Ross Pop safety valves are probably best sources separately, in metal. They are actually possible in resin, with wire reinforcement too, but casting them bubble-free and flash-free on a kitchen-table basis isn't so easy, and cleaning off flash without damage to the tiny castings or to one's own temperament isn't a job that suits all.

I think it has already been mentioned that other small castings to be prepared will included the little piano-front cover that sits between the frames in front of the smokebox, the cylinder front covers, the rear sandboxes and possibly some sandbox lids. If I can work out what might be required and whether they can be made satisfactorily, there may be some sort of pieces to sit behind each motion bracket too.

I may get back later with another picture to show the clash between OO wheels and the un-trimmed lower boiler. I'm hopeful that the boiler has been by far the biggest element in my part of this project, in which case I may now be on a downhill run towards completion.

[Atlantic 3279]

Thanks Andrew,

Note now made to check dome height. An alternative dome and a plant pot chimney might be considered - but nothing guaranteed at this stage.

[Atlantic 3279]

Allowing as ever for the possibility that intentions shown in works drawings may not agree exactly with what was built, via scrutiny of the works drawings in Johnson's book, all much reduced in size and with marked dimension tiny, faint in many places and downright illegible in others, I've gleaned the following figures, with doubt in one or two places whether the exact dimension was 1/2" or 1/4".....

D10 original dome height above boiler clothing 1' 5" 1/4

B8 drawing and 8N (B6) drawing appear to show the same. 8N dome casing is shown as 2' 7" 1/2 outside dia just above the bottom flare. Safe to assume the same for D10 and B8 I suspect.

9P (B3) drawing clearly does not show the much later very low dome cover that was originally created for locos such as B7/2 and D11/2 requiring wider route availability, and none of the B3s were built after grouping to suit LNER gauge, BUT the dome height is shown quite legibly as 1' 2" 3/4, i.e. two and a half inches less than original Director, Glenalmond and 8N. The drawing is reproduced without a date. I accept that some early views of B3s suggest a dome height the same as D10, B8, B6 etc so I form no firm conclusion at this stage.

The resin dome in preceding images is 5.1mm high, 10.3mm dia just above the flare, close to the indicated dimensions for the B3, although its "top edges" are possibly not quite rounded enough to match. I may look for alternative domes.


Returning to developments, this image missed the boat earlier:

Illustrating the point about wheel top clearances, I fitted a set of Bachmann A1 driving wheels to the frames. They are 26mm dia over treads, 28mm dia over flanges, and owing to their insulating bushes having an argument with the outer faces of top-hat bearings in this set of frames (which bearings I do not want to file back) I could only close the BTB dimension down to 15mm rather than a more typical 14.5mm for OO. There was therefore no sideplay, something which many builders are likely to wish to allow.

In the "rigid" state, this wheelset in the leading coupled wheel position does just allow the un-cut boiler to sit down as it should, but the wheel flanges are within "having to get married" distance of the boiler:

Placed in the rear axleway, these wheels totally prevent the firebox end of the boiler from sitting down because the lower firebox sides sit directly on the flanges. Compare the firebox position relative to the cab with earlier views. Even if the firebox lower sides are trimmed, the situations will simply be as per the leading wheelset, confirming the need to cut away part of the boiler bottom for use of OO wheels of the right size - but as it's all hidden by the splashers and is the same area needing to be cut out to take a motor it matters little.

The backhead as currently shaped surprised me by fully clearing even the large wheels of B3 size. It may end up needing some lower corner fill-in pieces for the B7!

[LNER4479]

Thanks, Graeme for those latest boiler progress photos. I'd better keep pace with details of the test build, starting with the chassis.

Here are the frames, prepared ready for assembly. The spring detail is an overlay etch. Half etch cut-outs are provided on the inside for those who wish to fit proper axleboxes. The non prototypical down piece between the front and middle axle holes is an alternative mounting point for the brake blocks, as there's not much clearance to play with here.

Here it is all set up in the Poppy's jg, being soldered up. The coupling rods (usual two etches, sweated together for a chunkier look to the rods) have been assembled to assist in ensuring accurate alignment of the frames. The rods can be jointed but I haven't bothered on this build.

Everything fitted fine (spacers have the usual half etch slots allowing use for either EM/P4 or OO, as in this case). Nice and square n true with the wheels fitted (this is just a spare, older set of Romfords - I'll be using newer RP25s for the finished model) and, although not shown here, where subsequently fitted with crankpins, a test fit of the rods saw it running smoothly without any tight spots. A promising start.

(More to follow)

[LNER4479]

Here are the bogie sides assembled. A total of three etches for each side which give some nice layered detail. There was an error in the positioning of the curved slot for the bogie centre pin; that has subsequently been corrected for the pre-production etches.

Here is the assembled bogie. Front and rear bracing bars are added in holes lined up the outside line of axlebox rivets.

The cylinder formers simply slot into the mainframes at 90 degrees.

With the front former soldered into place, a length of 2mm rod is used as an alignment check to check it passes through the centre of centre wheelset - the rear former can be adjusted to get this accurate before soldering up.

(Final part to add)

[LNER4479]

The most challenging part of the chassis is the distinctive motion bracket. This folds up from a single etch. The top profile of its shape has been refined slightly for the pre-production etch. There is a front and back to each bracket.

These are quite small parts! Four slidebar assemblies in total; each fits in a half-etch on the inside of the brackets.

This shows the bracket assembly now with the slidebars fitted. A certain amount of fettling of the slidebar assembly and crosshead slides was required to get a smooth running fit but I guess that's better than things being too sloppy.

This shows the overall effect of work done to this stage. The bracket assembly is only tack soldered at this stage as it need to come off to allow access for the next stage. A clue to this is given by the 1.5mm tube soldered laterally in front of the motion bracket. That's for the outside valve arrangement which I'll feature next time.

[Woodcock29]

Excellent work Graeme and Graham.
Andrew

[nzpaul]

I know I'm being a bit quick off the mark but... I've got my bits ready.

No real hurry of course, the truth is I keep quite a lot of parts "in stock" so when inspiration strikes I'm fully armed and ready to go. Really looking forward to building one of these kits.

Cheers
Paul

[Atlantic 3279]

Nothing wrong with being organized!

[9E]

Fascinating to see this project progressing.

A few photos of Valour allowing comparison of original and later lower dome:

https://railphotoprints.uk/p284421216/h ... #h1c13aea3

https://rcts.zenfolio.com/steam-lner/b- ... #ha12ebdbe

https://transportsofdelight.smugmug.com ... i-5jDqtsg/

and one of the Caprotti fitted B3s also with a lower dome:
https://rcts.zenfolio.com/steam-lner/b- ... #ha12ebbc5

If snifting valves and flowerpot chimneys are being considered then you may need to make a decision whether to account for the period that 6165 had snifting valves either side of the chimney (along with 6166?) and the others had one to one side rather than the later position of the snifting valve behind the chimney:

https://transportsofdelight.smugmug.com ... /i-PpmgVnb

At least the other variations like ash ejector position are easily dealt with by just drilling a hole in a different place!

Simon

[Atlantic 3279]

Provision of laterally mounted snifting valves, if desired, will have to be a matter for the builders.

I've been measuring domes on other models. Even the dome on the Bachmann / NRM Butler Henderson isn't as much as a scale 1' 5" tall. I do have some turned domes in my boxes of "handy one day" parts, one or two of which are of that height or maybe slightly more, but they are not of large enough diameter above the flare and they have to much flare around the base. If it really proves necessary I may modify a dome of the type shown in previous pictures to make it almost 1mm taller, simply by sawing through it and adding a disc of plasticard, then blending the joints. I could if absolutely necessary round off the shoulders slightly more too.

The dome on an old Hornby B12 is somewhat similar to the later low dome on the B3s.