Atlantic's works: Portable layout - Scenic details next

[9E]

Inward sloping tender guard irons too.

Simon

[Atlantic 3279]

Thanks. Perhaps those features were additions long after the production of the surviving copy I saw of an official drawing. The vertical handrails will be a nuisance, as I may have to move the lamp irons to accommodate them and they'll probably get in the way of the eventual lining unless I add them at the very end of livery application.

[Atlantic 3279]

Oddly enough, now that I've used some of the brain I was born with, and had a look in Dow's "Great Central Album" I've seen plenty of evidence for the rear guard irons on the Parker 3080 gal tenders, even in works photographs of the early versions of the 0-6-0s. They are plainly visible, many years before rear steps were added masking the view. The frustrating thing is that every picture I've found of a 4-4-0 stablemate is either taken from the typical angle that shows the loco well but leaves the tender receding into the distance with its rear hidden, OR, its a side view with the rear of the tender cropped off! As for the best side views of the 0-6-0s, well before grouping, it may just be the perspective but I've detected no vertical rails on the rears.

[Atlantic 3279]

Pending more evidence, Doubting Thomas here still hasn't added any vertical handrails to the rear of the almost complete tender, but as this image shows, assembly of the main easy bits of a second D7 and tender is well under way and both tenders now boast rear guard irons. Short of enough Kean-Maygib sprung "proper" GCR buffers and either lacking, or being unimpressed by alternatives, I've also had a go at casting some resin examples, without greatly impressive results. They are okay, after a lot of careful cleaning up. Damned by faint praise...

As the weatherboard was mentioned in a question a short time ago, I thought I should try to illustrate the consequences of sticking two such items together in order to overcome the fragility of the thin resin item. On the left in the image below, I have filed / sanded the beading off one of the faces of each of two weatherboards then stuck the two together. On the right is a single thickness weatherboard. Both are only standing loosely in place so are not truly upright and are a bit wavy as they are not braced by attachment to the more rigid front coalplate. The single thickness plate on the right is thicker than true scale, certainly as thick as I'd like to see. Including the edge beading, that on the left has a scale thickness of about five and a half inches! It is however much stiffer, and for a model likely to be heavily or inexpertly handled it would probably stand much more chance of survival. The ideal answer for maximum strength of course would be to cut one from sheet metal and add the necessary beading...

[Chas Levin]

Just catching up, lovely work as usual Graeme - particularly taken with the fireman's handrails, very neat procedure...

[Atlantic 3279]

Further D7 developments: While continuing to work on details and beginnings of livery on the first resin D7 I've also been getting a second example as far as the basic (but smooth) running stage. For this second loco, I had long planned, simply because I had some left over from my Gresley 4-8-2 project some years ago, to make use of Hornby A4 coupled wheels and axles, thus avoiding the approximate £10 per set for Scalelink, or more still for Markits if I wanted self-quartering wheels, or a bit less for Gibsons which require quartering. The moulded-in balance weights, in the wrong places and styles for a D7 are a drawback with the Hornby wheels of course, and the larger diameter (especially over the flanges) compared to the Scalelink 26mm wheels used on my first D7 could have been a problem had I not catered for those in the production of the master parts for the D7 bodies. Even with that planning I did however find that I had to do a certain amount of filing out of extra clearances in the resin castings, on top of thoroughly removing all flash and casting defects, but let's not dwell on that...
I'd noticed when first deciding on the Hornby wheels that they had brass inserts to receive Hornby's crankpin screws, apparently tapped 10BA in the coupled wheels, but with smaller drillings in the driving wheels which had a larger brass projection to carry con-rod and return crank. As I had one set of each type I enlarged the holes in the driving wheels, tapped those to 10BA too, trimmed off the brass inserts in all cases flush with the outer wheel faces, and then had scope for screwing in Romford/Markits plain crankpins tight up to the wheel faces, so that the rods when fitted would not project excessively.

It was not my plan to use the Hornby 21 tooth plastic final drive gear. That later pulled off the splined part of the axle relatively easily and was replaced by one of my cheap moulded gears from Squires, which, with centre hole carefully opened out to 3mm pressed into place nicely on the splines.

[Atlantic 3279]

With options limited by the overall size of the gears (especially the one that goes on the axle and has to be smaller than the wheel diameter) the suitable gears in the selection from Squires were these:

Although the two larger sizes offer either a plain boss or a ten-tooth central gear option, I did not favour any of the straightforward possibilities. I thought that a 42:1 single stage reduction wouldn't be quite enough for a loco with 26.7mm wheels, small motor, and not requiring a particularly high top speed. 90:1 reduction would have been possible using a 30 tooth final gear and a 30/10 tooth intermediate, and would suit a shunter quite well, but I liked the result I'd got with 48:1 gearing in the first D7 drive mechanism, and the way I achieved that was to combine a slice from one of the 10 tooth inner gears with one of the 16 tooth type. With centre holes carefully enlarged to 2mm to fit nicely on a 2mm shaft, sides rubbed down flat, and two tiny spots of superglue applied, the gears were bonded together and the joint further reinforced by drilling two 0.5mm holes and inserting stubs of brass wire, with more minute amounts of superglue. I had previously learned that even a slight excess of glue creeps into the troughs between the gear teeth and ruins the meshing qualities...

One the bonds were firm, the centre hole was enlarged very slightly further to allow the gear to rotate easily (but not sloppily) on a 2mm shaft.

[Atlantic 3279]

Whilst I liked the gear ration in my original drive system, and my arrangement of the motor sitting forward in the boiler barrel to give space for a solid block of lead in the firebox, directly over the driven wheels, had given smooth running and adequate haulage ability, the motor position made separation of body and chassis (as well as re-fitting) a bit of an awkward procedure. The boiler had to remain separable from the cab/running plate unit in order for the motor to slide easily in/out of the boiler, and to allow the weight to go into the firebox. Second time around I therefore decided to do things more conventionally, reckoning that there might still be enough scope for stuffing the chassis unit with lead below motor level, adding a bit to the middle of the boiler, loading tender weight onto the drawbar, and even lining the outer splasher faces with some thin lead sheet.
With reference to drawings, scaled photographs, and the previous model I therefore worked out a drive layout including the 48:1 ratio but putting the motor in the firebox, able to descend directly when the chassis is removed from the body. Here it is planned out on paper, with the Mitsumi motor and intended gears also shown.

After cutting side frames from just two layers of 0.5mm plastic, laminated to give the right frame contours in the most visible areas, I initially drilled only the drive axle hole and that for the intermediate gear, in positions plotted from the paper plan, taking care not to get the gears too tightly together. Using both side frames, a 3mm drill shank to act as a dummy axle, and a 2mm drill shank to represent the layshaft, I then checked that the gears did not bind. I've found in the past that if there is tightness, it is possible to move the holes for the layshaft slightly by filing one side of the hole and sticking shreds of plastic into the opposite side using solvent. It is not quite as alarmingly crude as it sounds, as the layshaft itself stay still in my gear system, the intermediate gear rotating on the shaft.

Notice that there is also a 1mm thick plastic plate already screwed to the end of the motor in the above view, ready for bonding to the sideframes (with reinforcement around the joints) in the appropriate position. The nylon worm is also fitted to the armature shaft. The gear was initially pressed onto some 2.0 / 1.5mm dia brass tube. The shaft was then roughened slightly with a sharpening stone to give a key, three small washers added to take up the potential space between the worm and the motor bearing (thus helping to control end float) and the "bushed" gear slid onto the shaft after a thin paper spacer. A spot of one of the Loctite retainers had previously been introduced to the brass tube, and as the worm was pushed home the tail shaft of the motor was also pushed from the opposite end to take up all slack. Once the retaining compound had set the paper spacer was removed. The result was a nice freely revolving motor shaft with minimal end float, helping to ensure quiet running.

[Atlantic 3279]

I had a couple of 3mm top-hat bushes so I enlarged the drive-axle holes to take those. Using some Gibson rods I then double checked the plotted positions for the rear axle holes and drilled those. I had to use 3.5 / 3.0 mm brass tube for rear bearings, having no more top-hats. I actually used a single, full-width bearing tube, with an oiling hole drilled in the under side.
With various 2mm thick frame stretcher pieces completing the basic frame structure, motor added (with paper spacer between worm and intermediate gear), joints reinforced with added plastic fillet pieces, lay shaft cut to length and trapped in place by cover pieces bonded over the holes, axles/wheels/crankpins/rods and temporary retainers all added, I had this result:

One thing I had found by the way was that the drive axle and final gearhave to go in before the two side frames are united by the stretchers, because the gear splines on the axle won't pass through a snug, turned brass 3mm top hat bearing. The fact that the original Hornby bearing is such an "easy" fit that it will slide over the splines, and even then supports only one end of the axle, makes it no surprise that driving wheels on Hornby's LNER Pacifics wander around in a way that some modellers really dislike!

[Atlantic 3279]

Here we have the drive unit and the wheeled-up bogie, plus the cab/running plate unit at the auspicious moment:

After a bit of filing of the inner faces of the resin "pivot blocks" between the splashers, plus some precautionary rounding or bevelling of their edges, the items were a nice easy fit.

Incidentally, my choice of dimensions for the Gibson rods may surprise some. Whilst the correct dimension is 8'7", or 34.3mm in scale, I did not opt for the nearest ready made 34mm, nor did I employ universal rods made up to exact length. I actually used 35mm rods, quite deliberately, in order to avoid excessive problems with flange clearances around those vital pivot blocks between the splashers. I was glad that I used the ready made length, as there is really only room for one thickness of metal in the rods, allowing for the thicker Hornby wheels, the crankpins and the necessary retaining washers. Having designed-in this option at an early stage I was still able to accommodate the flanges at the front of the leading splashers and at the rear of the cab.
The chassis unit has since been beefed up with blocks of lead, brass pivot beam added across the top for attachment to the body, pick-ups / wiring added, and it runs very nicely.

Careful observation of the above image also shows that I added the upper front to the cab, and the supporting rear pillars (with holes carefully drilled to get them to be vertical and of matching appearance) at an early stage, having discovered that it is otherwise alarmingly easy to break off the slender parts of the cab sides above the rear cut-outs! Fitting the roof too, as early as is conveniently possible, isn't a bad idea either.

[Atlantic 3279]

Meanwhile, application of details and basic livery to the first resin D7 has reached this stage:

After a coat or two of paint (in this case red primer and satin black from aerosols) the rivet detail that was only faintly visible on the grey castings now stands out quite nicely. The horizontal cab handrails, the vertical rails on the rear of the tender, and the buffers are only a dry push-fit at this stage, so that I can move them out of the way when adding the lining. The front buffers are sprung Kean-Maygib (hen's teeth?), but without enough for both locos and both tenders, and being less impressed with readily available alternatives, I've cast some basic resin examples for the tenders.

As the second loco is now capable of running without falling to pieces, it just had to sneak into a picture too.

[jwealleans]

The front buffers are sprung Kean-Maygib (hen's teeth?)

Range available from Branchlines, I believe.

[Atlantic 3279]

I've previously bought LNER spencer buffers from there (a few years ago now), but when I looked to see what current information (if any) could be gleaned from the web, I found (on the now dead BIG BIG forum) only comments or suggestions that any form of regular supply of the range had fizzled out at least six to eight years ago. If I could get some KM435 in a short time for less than a fortune, or even some of the Bachmann parallel case sprung type to which I could add a square base, I'd be happy, but the days of traders holding regular stock of anything of that sort seem to have gone. I had a look at an image of some of the sprung Gibson type, but noted that there's no beading around the mouth of the socket, and some of the turning looked a bit irregular...

[Atlantic 3279]

Well I've now attempted to e-mail Branchlines regarding availabvility. If I get any response I'll share the news.

[manna]

G'Day Gents

Little Ripper.

manna