Atlantic's works: Portable layout - Ground Signals Again

[S.A.C. Martin]

That's brilliant Graeme, thank you.

Right, will investigate further, and will fire off a few PMs I suspect too! Will stop cluttering your thread now, my apologies!

[Atlantic 3279]

A brief reversion to matters A2/3, mainly so you can all have a laugh at me, or maybe just think "yes, I've been there too".
Owing to the joint in my two-piece rubber mould for the smoke deflectors having strayed slightly from the intended line (owing partly to the extreme ability of the liquid rubber to creep when making the mould, and partly to the fact that I hadn't arranged the master quite as I'd imagined before pouring the rubber) I was getting an annoying joint line with a slight step on part of the outer face of a RIGHT smoke deflector every time I cast one. It was capable of rectification on each casting, but doing this to each casting that I produced was becoming tedious, so I decided that a new mould was well justified. I'd have made a new one long ago but I had run out of rubber so I just carried on with what I had. Anyway, I re-made the mould for one deflector, and was impressed with the quality of the first two castings to come out of it. Then I noticed - I'd re-made a LEFT mould
I'm now making another, a RIGHT one this time. Here's the master on a bed of plasticene ready to have the moulding box built around it.

The tapered sides of the plasticene will leave a hopper shaped impression in the base of the rubber, and when turned over with plasticene removed, I can pour the other half of the mould. The second half will then "plug in" to a controlled depth, and all of the joint lines will be on the back of the deflector, near the edges, easy to clean off.

[Atlantic 3279]

Back to the A1/1. Although this image was so poorly lit and poorly focussed that I've had to re-touch it somewhat obviously, here's how I've indented slots in the underside of the running plate to act as a guide when making slots all the way through to accommodate the tabs on the bases of the re-used Hornby mech. lubricators and oilboxes. I've also scribed in guid positions for the sand-fillers (SF). As you can therefore see, I've filled in the void behind the angles or valances with 40 thou white plastikard sheet so as to make the whole of the running plate thick enough to cast in resin.

[Atlantic 3279]

It was time to think seriously about proving a method for joining the "side" running plate pieces to the cut-down A2/3 "front" piece. The joint sits in the space just above and ahead of the cylinders. It is possible to accommodate some reinforcement below the joint, avoiding a hopelessly flimsy butt-joint (or the complications of drilling and pinning into the two faces of the butt joint), but the overlapping pieces have to be shaped to miss the tops of cylinders, stretcher, steam ducts etc. The picture shows the shapes, glued to the front running plate piece, though I had to trim a little more at the rear edges after taking this as the running plate wouldn't go down fully over the "front inside corners" of the cylinder tops.

Briefly held together off the chassis:

As I have to separate parts again and use them as masters for castings, I haven't glued the joint to the side running plate pieces of course, instead I've drilled and used a tiny screw each side, inboard of the area where the main steam pipes will be glued on. That makes thing rigid and allows me to be sure of what actually fits!

Speaking of the steam pipes, here are the elbowed items, cleaned up to a fairly final shape.

[S.A.C. Martin]

Definitely happened to me, in terms of the right to left mixup!

All looking terrific so far Graeme, I feel silly giving so many plaudits with little in the way of actually contributing usefully to the discussion. However, on the one point - perhaps using the modified resin component for the front running plate you've produced there in the production of a dedicated A1/1 mould would have benefits? if you were intimating that in any event, please disregard this last comment.

[Atlantic 3279]

I'd noticed that although the non-matching widths of loco and non-corridor tender help at times to disguise the error, the rear of the Hornby A3 loco running plate sat lower than the front of the tender soleplate. Measurement, and comparison with the ex-Bachmann A2/3 and its tender, convinced me that the error was probably in the loco, and besides that, the rear ride height of the loco looked a lot easier to tweak upwards than the tender's ride height might be to lower.
As I wasn't making a new rear end for the chassis for this loco (unlike previous adventures with the W1 and the recently mentioned mythical 4-8-2) and the body-mounting lug on the rear of the chassis is cast in hard metal with little scope for any alteration, I needed instead to alter the height of the slot in the plastic backhead into which the lug fits. If my memory were perfect in every detail, my recollection of the near-identical Hornby A4 cab structure would have given me a quick solution to this problem, but memory being imperfect, I did this:

Firstly I split the glued-in raised cab floor from the main body moulding using a thin blade and careful leverage.

This revealed that the slot is hard against the lower cab floor, at the base of the backhead, so in order to lower its bottom edge I filed material away, being careful to only over-run with the file onto areas of the cab floor that would again be covered when the interior was refitted.

[Atlantic 3279]

I had intended to also lower the top edge of the slot by gluing slips of plastic into it. I then noticed that because of the way the body sits on the chassis, I could prop it up to gain extra height, taking adavantage of the deepened slot, without having to trim pieces of plastic to fit accrately in that little slot. All I had to do was stick a couple of layers of 20 thou plastic under the slot, at the front underside of the cab floor, thus:

The reason for the red dotted line on those packing pieces may now be obvious too. I didn't need the inner cab floor out at all. I could have simply cut away the bottom of the backhead / front edge of cab floor below the slot, back to that dotted red line, then stuck on my two pieces of plastic. Doh!

[Atlantic 3279]

No matter, one way or the other, the loco running plate and tender soleplate heights now match, and the cab heights of both of my Thompson monstrosities are the same:

As you can see, a strip of 5 thou white plastic, and a slightly narrower black 20 thou strip have been used to represent the reversing rod cover.

BUFFERS

Great Northern retained the Gresley / Spencer-Moulton double-acting buffers. I know that fully working, genuinely double-acting models of these can be assembled (with care and skill) from the Kean-Maygib parts, at about £5 per pair. I do have a pair in stock, but reserved fior another project, and as I don't seem to be able to get the Kean Maygib buffers "just whenever I want them", I didn't want to use up my stock. I also had some whitemetal ones (not sprung) or some sprung Group Standard buffers which would be better than nothing, but not quite right. I'd looked at the sprung Hornby buffers on the donor loco, which look about right, even if only one section is sprung rather than two. For some time, they appeared to me to be impossible to remove for re-use, at least without undertaking some risky butchery. However........ I then noticed that there was a recess in the bottom edge of the buffer beam (arrowed red in the image below) and once I'd seen that I was then able to see that the buffer beam itself appears to be a glued sandwich. So I started splitting the face of the buffer beam from the backing, and found that the buffers are only trapped in the face of the beam. Once the layers are split, and the buffer is cut around its square base (either job can be done first), you have a nice separate sprung buffer, although its square base is a bit thick. The edges of the base can of course be filed down at the rear, and once the not-now-needed square base is filed away from my resin buffer beam, a freebie Spencer Moulton buffer can be fitted:

See also how obligingly the SEPARATE Hornby front numberplate comes off the smokebox door, allowing a "change of era" relocation of number plate witout much scraping, filing, sanding and repainting, unlike recent experience with the A2/3. Come on Bachmann! You could do the same.

[Atlantic 3279]

Making up the unique tall, narrow, sand-fillers and shileds for the front sand-boxes on GN turned out to be quite a simple process. The fillers themselves were pieces of 2mm platic rod with a collar of plastic tube glued on, the top then being smoothed to reperesent the cap. The backing plates were rectangles of 40 thou plastikard, drilled to take the filler tubes, and with 1.5 or 1.75 mm wide microstrip stuck around the egdes. I also added the supporting web below the filler pipe from a triangle of microstrip. All filed up to tidy the shape after solvent had evaporated. Here's a general look with the better sand-fillers and buffers on. Tidied-up steam pipes back in place too, and as you may have noticed by now, superfluous handrails removed from smokebox sides:

Sand filler inclose-up:

Although the Craftsman sand-fillers were fairly good for the other two positions on the loco, I also added the supporting web below the filler pipe on those too (by sticking microstrip into a slot sawn in the casting). Yes, I must be mad.......

[Atlantic 3279]

The Hornby A1/A3 front steps have also been re-used. After trimming of the top portion of the backing plate (above the top step), I stuck the steps to a simple thin brass stretcher glued to suiatble areas of the resin on (and behind) the lower edge of the buffer beam:

Even with thse quite narrow lower steps attached as far forwards as possible, I could see that I was having trouble with the top-front corners of the bogie catching the steps. I then realised of course that I could get rid of the troublesome corners of the bogie, as I did not need a bogie carrying Gresley-pattern dust shields and two sets of guard irons. I unscrewed both the dust shields and the "frame" guard irons. I filed the front of the bogie back to a simple flat upright face (like the front of a Thompson bogie with plate stretchers) & filed off the ridiculously puny cast representaions of the bogie guard irons. I then filed off the top of the area of the bogie onto which the separate fittings ahd been screwed, trimmed and re-bent the "frame" guard irons to look like the Thompson ones that I needed, and epoxied these to the front of the bogie. I even bent the "stretcher" posrtion of the guard irons to try to give the illusion of a dip in the top of the front stretcher plate of the bogie. Ridiculously time consuming. I won't do it again, unless I have to....

[Atlantic 3279]

Plenty of clearance between steps and bogie now.

Here's the appearance of the bogie, steps and buffers:

[mick b]

I got some Spencer Buffers recently from Branchlines.
These have no spring in the pack but a machined spacer which the thin rod of the buffer passes through and then bent from behind. There are no instructions on how this is supposed to work !! and I cannot see anyway of achieving any spring whatsoever. Are yours the same ?

Great work on that lovely Thompson Loco.

[Atlantic 3279]

Doesn't sound very good Mick. My recollection of those KM's used on my P1 was that springs were supplied, but as you've found, there was little or nothing in the way of instructions! If I remember correctly, I deduced by trial and errot that the spring could not go in full-length either ahead of, or behind, the intermediate section of the buffer, being miles too long so that even when fully compresssed the buffer was far too long and "plain wrong" in appearance. Besides which, fitting the spring in one or other position meant that only one section of the buffer was sprung, making the three separate sections a waste of effort. I think I then tried half of the spring, either side of the middle section of buffer, finding in the process that it was a swine to cut and the pieces were very fond of trying to fly off into oblivion upon being cut. Also the cut-ends of the spring had to be free of kinks and projections, otherwise they snagged on the other internals of the buffer as it compressed, making it then refuse to extend back to length! The half-springs showed that the double-action of the buffer could be made to work, but again it was too long and its springs bottomed-out before the rams were fully pushed in. I suspect that in the end I fitted about a third of the supplied spring in eaxch position, then bent the "tail" of the main ram over to lock the construction together (or maybe I put a disc of plastic on the tail of the ram and held it with a tiny spot of glue or retainer?).

Now I've just found and checked my latest packet of KM436, which came from Cove Models a good year or more ago. I see it does again contain springs - three in this case, much tinier than coupling springs, and (a revelation!) some folded instructions. It is still securely stapled-up so that nothing gets lost, but I can see part of the instructions which appear mention fitting "half" of the spring in each location so as to get the double action. Only trial and error will tell me whether "half" of these particular springs is the right amount. Do you need to chase somebody up about some missing parts Mick?

[jwealleans]

I got some for a K3 I was detailing at the same time as you got yours, Graeme and I don't recall any problems with assembling or fitting them. I can't check the loco as it's no longer in my possession but IIRC the double springing worked very nicely.

think I still have a spare pack if you want me to look it out.

Didn't you get yours for a P2, Graeme? What's happened with that?

[Atlantic 3279]

The P2 kit is still waiting obediently, yearning to be built. I must stop having other "good ideas" and then I might actually get on and build the poor thing, before I'm reported for cruelty to kits.