Atlantic's works: Portable layout - Scenic details next

[60526]

Must admit that I'm fascinated by this conversion and I'll add my thanks for you producing these articles. I have two A2's required for my loco stud. One is 60526 Sugar Palm, only because I saw it going through Wood Green in the early 60's. I'm making this from a DJH kit because at the time I was disappointed with the pulling power of the B'mann A1 and wasn't expecting much more from their A2. The other A2 is 60500. I was thinking of buying a PDK kit until I saw this article. I'm looking for the loco to pull 12 B'mann Mk1's. Has anyone any experience of what the B'mann A2 can pull?

[S.A.C. Martin]

Graeme, these notes are terrific. Reading with great interest. RE the pulling power of the A2, it's similar to the Bachmann A1, most of my A1s can take nine Mk1s on the flat without copious amounts of slipping. I suspect they'd need more weight over the drivers to pull any more.

[Atlantic 3279]

If I can get on of the operating crew to sneak the converted loco onto Gamston Bank for a cameo appearance on 12 kit built (metal?) coaches on Sunday morning, I may have an answer regarding that question of haulage capacity. In anticipation of that feat, I've put some extra lead sheet in the front of the boiler and the rear of the firebox, to compensate for the loss of the cast metal front of running plate and backhead.

Alternatively, I can put it on on my loft circuit, with its 3 foot radii, and couple coaches to it until it cries "enough". I've got maybe eight extended/detailed old type Hornby Gresleys, three or four etched brass bogie coaches, some of the short old Hornby Gresleys, 5 Lima mark 1s, 5 aluminium BSL/Phoenix artics, and four suburbans I can add before I start to run out of ammo, so I reckon I can test to the limit.

[Atlantic 3279]

On with the valve gear construction notes:

If you have not already done so by this stage, it will be much more convenient to now separate the parts of Bachmann's valve gear that hang on the crossheads, from those that are attached to the old motion bracket. Take out the rivets at the joint between the top of each combination lever and radius rod, and put the "rear half" of the Bachmann valve gear aside safely. You will then have less unwanted stuff hanging from the rear of your cylinder unit and getting in the way of other work.
Once you've then fitted and briefly test run to prove no binding with your modified con-rods, the next point I would address is the replacement of Bachmann's wrong-length radius rods with the Comet items that are more compatible with the motion bracket structure that you'll be fitting. Fit the Comet radius rod (it goes outside the combination lever at the joint) with either fit one of Comet's rivets or solder in a pivot pin, as you prefer. I hadn't tried rivets before, but after a couple of trial attempts at swelling the end of the rivet over to the required degree I was actually quite impressed with the speed and ease of the method.

Throughout this stage of the work you'll have the cylinders and the part-built motion bracket on & off the chassis until you are sick and tired of fitting and removing them, but unless you can think VERY clearly ahead this is the only way to get access to do the various jobs and to undo any slight mistakes. You'll also get fed up of the number of times you have to un-ravel the tangle of part-complete valve gear that is hanging from the crosshead, slide the valve rod back into the top guide in the cylinder moulding, and re-engage the crosshead in the slidebars as it repeatedly falls out. But persevere....

Next, with the cylinders on, the valve rod in its guide, the union link/comination lever/radius rod attached and in their proper positions, and the part built motion bracket unit in place, you can move on to complete the construction of the motion bracket/expansion link/lift lever.

[Atlantic 3279]

Please bear in mind if reading this section that it covers only the original trial adaptation that I carried out using Comet V2 valve gear parts. In 2012 I switched to the use of a custom-etched set of valve gear parts specifically suitable for the "Thompsonization" of a Bachmann Peppercorn A2. I can arrange to supply those etched parts to others. Please contact me by means of a PM if you require parts.


Here, I suspect, is one of the most crucial parts of the job for the sake of appearnce and function of the valve gear. This diagram attempts to show how I arranged the rear end of the radius rod, the lifting lever, and the expansion link, between the inner and outer parts of the motion bracket:

The red and blue lines on the image represent (in ridiculously extended form owing to the "exploded" nature of the image) the pins that I used to link up the parts, the red one being effectively the trunnion of the expansion link, and the blue one being the weighshaft for the reversing levers.
I suspect that the best order in which to solder the assembly up is something like this....
Dry assembly all the parts as indicated, including a paper spacer on the red pin between the expansion link and the outer motion bracket. Pull the lifting lever and the radius rod up tight against the head of the blue pin and "spot" solder just those three items together. Now pull those three items and the expansion link out towards the outer bracket to trap the paper spacer on the red pin (that pin should be pushed fully home) and then spot solder the head of the red pin to the outer bracket. Tear out the paper spacer. The expansion link should now be free to rock back and forth, but not to waggle from side to side. If you want, you can now also solder both the red and blue pins to the inner motion bracket too, although there may be now need.

[Atlantic 3279]

Please bear in mind if reading this section that it covers only the original trial adaptation that I carried out using Comet V2 valve gear parts. In 2012 I switched to the use of a custom-etched set of valve gear parts specifically suitable for the "Thompsonization" of a Bachmann Peppercorn A2. I can arrange to supply those etched parts to others. Please contact me by means of a PM if you require parts.


A quick test run is again in order before finally turning to the eccentric rods, which must link the foot of each expansion link to the end of the return crank on the driving crankpin.

Comet's return cranks won't fit Bachmann's crankpin, and the Bachmann return cranks are in any case much more solid and three-dimensional in appearance so I opted to keep the Bachmann cranks. As neither the Bachmann nor the Comet eccentric rods are short enough for the A2/3 (i.e. either choice will need to be shortened) and as disturbance of the minimum number of joints in the valve gear seemed to make most sense, I therefore opted to keep the Bachmann eccentric rod, needing only to shorten that rod and join it to the foot of the expansion link.

In order to shorten and then fit the eccentric rod, my method is as follows, Firstly file the back face of the rod to get rid of the bright plating and reveal the "brassy" looking base metal. Fit the return crank to the crankpin on the driving wheel and rotate the wheel until the return crank pushes the eccentric rod as far forwards as it can ever go. Also push the foot of the expansion link ALMOST as far forward as it can go without knocking on the rear of the slidebars. Measure the distance from the foot of the return crank to the joint between the return crank and eccentric rod. This is the new length to which the eccentric rod must be shortened. Cut the rod about three quarters of the way along from the end that is attached to the return crank. Then cut the excess of length from the long portion of the rod, and re-join the two parts by soldering a (fairly short) strip of scrap brass to the rear face of the rods to bridge the cut. The logic of making the cut well away from the end closest to the return crank, and of keeping the bridging strip fairly short, is this: You don't want your repair strip on the back of the rod to clash with the return crank as the rod and crank pass over one-another. Check by swivelling the rod around on the end of the crank that the repair strip does indeed miss the crank entirely. If it does not, file down the repair strip until it does miss. Now join the free end of the eccentric rod to the inside face of the foot of the expansion link, by rivet or pin and solder, and test run again. MY ECCENTRIC RODS WORKED OUT AT 16mm HOLE-TO-HOLE, BUT DON'T ASSUME THAT IF YOU FOLLOW MY EXAMPLE THEN YOUR RODS WILL NEED TO BE EXACTLY THE SAME. IT DEPENDS CRITICALLY ON HOW YOU'VE POSITIONED YOUR CYLINDERS AND YOUR MOTION BRACKET.

At this stage the rear ends of of your slidebars still hang unsupported in mid-air, tucked below the bottom of the the motion bracket. You may not be able to raise the rear ends of the slidebars fully to the correct 1 in 30 angle unless you notch their upper rear corners slightly with a file so as to alleviate interference with the motion bracket. Once they sit at the right angle, and are snug against the bottom of the motion bracket, you can solder them to the bracket. This still leaves you with precious little holding the crossheads in the two-bar slidebars (remember that you cut away most of the rear plastic slidebar leaving just a short piece sticking out of the rear of the cylinder?). Tomorrow I'll show how I used part of a Comet slidebar to solve this problem too!
Then with any luck it will be a case of "Voila! Job done", something like this:

PS Throughout this description of valve gear assembly I've deliberately skipped instructions about drilling out joints in the valve gear to suit particular pin or rivet sizes - you'll have drill to suit your choice of fixings.

[Atlantic 3279]

Please bear in mind if reading this section that it covers only the original trial adaptation that I carried out using Comet V2 valve gear parts. In 2012 I switched to the use of a custom-etched set of valve gear parts specifically suitable for the "Thompsonization" of a Bachmann Peppercorn A2. I can arrange to supply those etched parts to others. Please contact me by means of a PM if you require parts.


Here's the slidebar fix. Cut a portion of the Comet slidebar as indicated:

Make the two folds in it so that it has a short "return end". Trim the long end of the bar so that this can tuck between the outer Bachmann metal slidebar and the inner plastic slidebar just behind the cylinder, pass the Comet slidebar behind the crosshead, and position its bent-over end to coincide with the end of the Bachmann slidebars. Solder that bent-over end to the rear face of the end of the Bachmann bars (i.e. just about where these bars are soldered to the bottom of the motion bracket too). The slidebars are now the shape that the Comet ones would have been if fitted in full, but you have not had to remove the Bachmann bars from the cylinders, get the Comet ones to fit in the cylinders instead, nor have you had to adapt or replace the crosshead to suit the Comet bars.
The long front end of the Bachmann bars can be secured back against the stub of the rear plastic Bachmann bar by carefully introducing a tiny spot of superglue, if you wish.
This diagram may assist you a bit more than my explanation!

[Atlantic 3279]

Oh, by the way, the return crank leans the wrong way on one side of the Bachmann chassis. With the crank off, if you inspect the end of the crankpin closely you will see two tiny projecting lugs, at opposite sides of the central screw-hole. On the rear of the return crank is an incomplete raised ring or collar, which locates over the end of the crankpin. Cast into that
incomplete collar are two notches into which the two lugs on the end of the pin engage. The position of the lugs and notches sets the "lean" or angle of the return crank.

I don't know why the collar was not cast as a full circle, but as it is incomplete, you cannot cut new notches in just any position you like in order to re-orientate the crank, but the collar does extend just far enough around for it to be possible, with the aid of a thin, fine piercing saw blade or similar, to cut new notches at about 45 degrees to the position of the originals. If you work out carefully at which of the two possible 45 degree offsets from the original position you need to cut your new notches, you will be able to screw the crank back on "locked" into position by the new notches, and with a "more correct" lean. BUT TAKE CARE, as you will be sawing slots into the cast collar quite close to the points at which it ends, so you don't want to be rough and clumsy as I can imagine it would be easy to break pieces off.

[Atlantic 3279]

Spoof temporary insiginia, just in case the loco manages to make an appearance in public at this stage, and a spoof box too, possibly in order to intrigue or irritate some of the more gullible "must have one of every kind" RTR collectors:

A look at a sample of the rough "Milky Bar" resin castings, the quality/size of the image being only an overview and not really sufficient to show the quality of the parts, but you've already seen those "as fitted":

And that reminds me, if you use those side frame overlays with the Bachmann cylinders on a stretcher as I did, you need to cut off the overhanging rear end of the exhaust steam ducts, otherwise, once you've glued the sideframes to the chassis block, you can no longer remove the cylinders! Removal of that last part of the duct is no detriment to appearance, as it would only sit tucked away behind the valve chest extension on the cylinder front anyway. The lower "dog leg" in the profile of the rear edge of the frame extension needs to remain, as it matches the shape of the leading edge of the back-plate on which the cylinder is moulded.

[Atlantic 3279]

"BACHMANN" A2/3 HAULAGE TRIAL REPORT:

I got bored with adding coaches by the time I was up to 15 bogies. These included:
D & S brass ECJS luggage brake
2x Jidenco brass ex-GCR Barnums
1 Hornby gresley with MJT brass sides
1 Kirk 51' full brake
The rest were plastic full length Gresleys from hacked-about RTR models or kits.
All passenger coaches have full interiors.
I didn't get the scales out to weigh the lot, but they were hauled with no suggestion of wheelslip save for a momentary one on restarting round a curve, and there were no immediate signs of motor-frying that I could discern.

I then cut the load down to just the ECJS brake, 6 plastic Gresleys and the MJT hybrid, and amused myself with the sight of the furiously twiddling valve gear and wheels as the train raced round my loft circuit with its 3 foot radius curves at a timed, scale, 105mph

I wonder if I'll find out what challenges Gamston Bank holds......

Vastly cheaper, and surely quicker and easier than building a full DJH kit. At least as nice in appearance if you take your time blending the body joints. I suppose resin resists being bent or dented by handling, but metal is less breakable. It's all a matter of personal taste of course.

[S.A.C. Martin]

Fully approve of the temporary identity

Looks good to me Graeme. Very convincing that box modification!

[52D]

Graeme you never cease to impress me. my sows ear to silk purse 0-4-0 sponsorship deal is still open when this project is complete.

[Atlantic 3279]

I'll get my books out and start looking at Pugs, and pondering, in due course.

In the meantime, I can report that the A2/3 managed to sneak onto Gamston Bank on Sunday morning, & do three circuits (as far as I saw, although I also went off for a look around while the crew played with my engine for a while). Its alotted turn was a parcel train of 9 bogie vans and three six-wheelers, if I observed correctly. I have no idea of whether the vans were metal, plastic or mixed.

[S.A.C. Martin]

It sounds like it was met with some favour on Gamston Bank - any pictures Graeme?

Is there much more to do, or shall I prepare some funds to send forthwith?

Looking forward to seeing it in the flesh, the Thompson A2s have grown on me the more I've read up on them. They are not elegant as with the Gresley Pacifics, but they are purposeful, and I find them quite handsome as a result.

I think you said an A2/1 was out of the question - is an A2/2 possible in the same manner as the A2/3? You could carve out quite a niche here. Definitely cheaper on the wallet, and I think it looks better than the DJH kit.

[Atlantic 3279]

Only pictures I have are on Hi8 video cassette, by virtue of one of my digital cameras being a battery-murderer and the other being of little use indoors for close subjects. If there's an easy way anybody can tell me to transpose the Hi8 to digital, without buying more equipment, I might be interested to hear.

Not far off readiness for dispatch now Simon, I'll keep you advised.

I think selected A2/2s, in the correct era, may be possible without unreasonable extra effort and expense, although the tender presents an extra complication as the rivets have to go unless a tender swap is possible. By the time you've ruled out A2/2s needing a different boiler shape with full V-fronted cab, and correctly catered for little details like beading or smooth sides on cabs and tenders, there's not a lot of choice of locos and dates.

A2/1 presents the problem of the need for A3/V2 boiler shape, full V fronted cab, A2 coupled wheelbase, but frames short at the rear as on the A3s/V2s rather than the Peppercorn locos. My front running plate, sideframe extensions, and method for relocating cylinders and rebuilding valve gear might be applicable, but the rest of the loco would appear to call for parts from two or three RTR models (or two locos plus the cost and trouble of building part of a SE Finecast chassis) which along with all of the adaptations required to make differently sourced parts fit together, would appear to kill any saving compared to building a kit. Bachmann A2 chassis and part of the running plate, combined with a boiler harvested from a spare Hornby A3 body moulding, and A4 or V2 cab from a similar source might just work, but in shortening the overhang behind the Cartazzi axle on the A2 chassis (and running plate) the position and integrity of two of the main chassis-body securing screws would be affected.