The Rhymney M Class saga, in 3mm

[NCB]

This started about 6 years ago when I was browsing the new Rhymney Railways Drawings book from the WRRC. I'd been thinking of a 3mm scale scratch- building project, and the M Class caught my eye. I liked the nice clean lines, and also I knew another 3mm Society member had been thinking of etching a 56XX chassis, which would do. So I set to. The M is now not too far off completion; the first few posts will be historical ones, of the stages involved to the present time, before I move on to current work.

 

The Rhymney M? In the early 1900s South Wales railways were still using a variety of Victorian engines, many including outside frames and saddle tanks. In 1904 the Rhymney broke with this by ordering 6 modern, powerful, rugged 0-6-2T engines from Stephensons, designated M Class. Nearly all subsequent Rhymney engines were of this arrangement, and other railways followed suit. As first of a new breed, the M went through a number of mods, but by the grouping had stabilised into its final form, with Belpaire firebox and revised boiler. One was fitted with a Swindon No. 2 boiler late in life; the last M disappeared in 1951. My model will be in GWR condition.

 

History - part 1

 

First job was to cut out the footplate from nickel silver, my preferred material. Then followed the tank sides, as seen below.

 

 

I'd also added the beading to the tank tops, from 5 amp fuse wire, at this stage. Next thing was to add the tank tops, and fret out the bits for cab and bunker:

 

 

Finally, I slung all this lot together:

 

 

At this point I reckoned I needed the chassis, to work out what motor/gearbox combinations would fit; I had a general idea, but needed something better before I tackled the firebox and boiler. However, looked like it was going to be a long wait for the chassis, so put the work aside and got on with other things.

 

Incidentally, a long while later I found out I'd misread the drawing; the tanks should extend slightly beyond the footplate. Doh!

Edited August 8, 2017 by NCB

[NCB]

History - part 2

 

Fast forward to a year ago, and still the 56XX chassis hadn't appeared. In truth, I'd realised that it probably wouldn't some time ago. However, in the meantime I had got stuck into etching, and had just successfully produced my own Dukedog chassis, not the easiest of prototypes. So, I set to work to produce an M chassis. There was space for 3 chasses on the etch I sent to PPD, so I included a Rhymney R Class and GWR 56XX, as well as the M, for possible future use. By the way, I'm using 14.2mm finescale track. Here's it is:

 

The chassis is built up from a single fold-up etch, my favourite sort of chassis; assembles in no time at all, and produces a strong, rigid structure. The brakes are separate etches and are hung from 0.6mm nickel silver wire.

 

I'm a fan of compensation, and in particular twin beam compensation where appropriate. I find it often results in better balance than classic Sharman, and also allows you to stick the drive on the compensated central axle in an 0-6-0. It's also an excellent way of approaching 4-4-0s (like the Dukedog) and other 4-coupled chasses. So here there are two beams on the front two axles.

 

The rear driving axle and trailing truck use a single beam, which also has a number of advantages. In this case the mounting point for a pony truck would be uncomfortably close to the rear axle. Bringing the pony axle in to the compensation system gets around this. It also means all wheels are carrying the weight of the locomotive body, which should improve running. The pony axle is allowed a fair amount of sideplay, and is also allowed to wiggle slightly; in my mind this allows it it move in much the same way as the axle on the prototype's radial truck.

 

Where axles have up-and-down movement I don't bother with hornblocks, to me an unnecessary complication, simply an etched slot in the chassis. In theory the distances between the crankpins on the second and third axle vary a bit, but not enough that a slight bit of slack in the coupling rod holes won't accommodate.

 

Here's the chassis with a test lash-up of a High Level gearbox and Mashima 1015 motor:

 

 

and here it is with the body on top, to see if it fits (the body will eventually sit slightly further back than shown here):

 

 

This gave me a better idea what would fit. The gearbox shown is a Compact+ with a Drivestretcher replacing the second stage; I hoped that this would give enough room to squeeze in a Mashima 1024 or 1224. It wouldn't, and the motor was a bit high. I was probably better off with a 1020 or 1220 and a standard Compact+, but I wasn't sure about this; it depended on how much space there was under the firebox front.

 

I decided I would have to build more of the body. I'd originally intend to build the whole thing using traditional techniques, but I'd been bitten by the etching bug, so I drew up the remaining body parts in Turbocad, and off it went to PPD, at which point I took a breather.

Edited April 19, 2017 by NCB

[Penrhos1920]

Nigel, the prototype frames were narrower behind the rear driving wheels so that the radial truck could swing around tight curves. Given that most layouts have even tighter curves than real life don't you need to do the same?

 

PS. I wish I was as brave as you getting a loco etched. I think I'm be brave drawing a 3D loco for printing.

[Michael Edge]

Nice to see somone else not bothering with hornblocks but I do think you need some radial movement for the trailing wheels.

[NCB]

I made the frames narrower than the prototype to allow for sideplay; each axle has washers to control the amount of sideplay I want for that axle. So the second axle has almost no sideplay, being the driven one. The first axle has a moderate amount, as much as the distance between the inside faces of the splashers will allow, the third quite a lot, and the final axle even more.

 

I intended to have minimum 32" radius on my layout, but due to a miscalculation there's one point where it drops to 29". With the chassis set up as described but with no motor, I could finger-push it around a 26" test curve, so reckoned it should be OK for my purposes, even though set up with motor and coupling rods it might be more comfortable with more.

 

The "wiggle" on the final axle (the slot is a bit wider than it need be) is intended to allow radial movement. I find left to itself the axle tries the keep at right angles to the rail, due to pressure on the flanges. This seems to work. 

[NCB]

History - part 3

 

Etches back from PPD, I knocked up and fitted the firebox, boiler and smokebox, after fitting the footplate subframe:

 

 

The subframe included fold-up splasher sides, and a couple of fold-up tabs further back, which allowed me to accurately position it under the footplate while I ran some solder round the edges.

 

The firebox front consisted of 4 identical formers, soldered together, with a slightly smaller one behind to act as a former for the main firebox wrapper, and a 3/4 circular one in front to act as a locator for the boiler tube, which was K&S. Once the firebox wrapper had been formed and attached, the firebox front was filed to shape, then the boiler wrapper attached to the boiler tube and that soldered to the firebox front. The next size up tube went on the front as a base for the smokebox wrapper.

 

So at this point I had a complete firebox/boiler/smokebox assembly. The tank tops were then filed so that this was a snug fit. The smokebox was intended to rest on a fold-up saddle, but It had turned out a bit too high so the bits were separated and the front and back reduced to the correct height. The smokebox/boiler/firebox was fitted using the saddle rear to support the smokebox, as seen in the pic; the saddle front was fitted later when the smokebox wrapper was added. Finally, a slitting disc was used to remove the boiler underside where the gearbox/motor was to go.

 

 

I could now try gearbox/motor combinations. As I suspected, the 1220 was a bit too wide to fit easily into the gap I'd left in the firebox front.  I ended up with a 1020 and the Compact + gearbox.

 

 

This shows the chassis ready to go. Testing it, it still managed the 26" radius curve, just, and was fine on the 29" radius curve. It needed the body on and a bit of extra weight to run smoothly, because with this suspension on all wheels it's fairly easy for a wheel to rise up otherwise.

 

That's the "historical" stuff. Now it's down to finishing the body; I'll post a bit more shortly.

Edited April 21, 2017 by NCB

[NCB]

On with the body. Obvious thing to do next was the smokebox:

 

After adding the front part of the smokebox saddle (see previous post), I bent the smokebox wrapper to more or less the right shape, using rolling bars for most of it then bending the bottom bits down manually. The brass tube at the front was then tinned; I use Carr's 188 solder and Green Label flux for most things, flows very easily and getting a a smooth coat around front and back edges of the tube was very easy.

 

I used small battens of hardwood at the base of each side to hold the wrapper in position (stops fingers getting burnt!), sloshed more flux over to help heat transmission, then whacked on the soldering iron, starting at the top and working down. When the top half was done it was safe to remove the battens and take a breather. The bottom bits were done using the battens again, still working downwards until the wrapper was correctly soldered to the saddle. All went as easily as I'd hoped.

 

The smokebox front I'd deliberately etched slightly high, and this was reduced until it fitted. The diameter was more or less spot on, just a smidgen over, so getting it in the right place and soldering it was straight forward. A few brushes with a file around the edges reduced it to the wrapper diameter and got rid of excess solder at the same time.

 

While I was about it, I added the front and rear buffer beam overlays. The only distinguishing feature of these is the raised circular area around the coupling hook slot.

 

The one bit I hadn't etched, because at the time I wasn't sure what was needed, was the piston front end cover which sits in front of the smokebox, and associated bits. So these were drawn up and added to an etch I was about to send to PPD. Waiting for these to finish the front area, I started to look at what was needed further back.

[NCB]

First steps with the rear of the body; fitting beading around the cab openings on either side, using 5 amp fuse wire:

 

This is the sort of job which I don't look forwards to but hopefully goes a bit better than anticipated! I straightened a length of the wire, and started on the straight vertical bit at the front of the opening. When I reached the curved bit I shoved a cocktail stick against the cut-out edge and guided the wire around that, moving the cocktail stick around the opening until all was done. I checked each bit while doing it, and gave the wire a nudge if it needed it. It's possible to go back and make minor adjustments if necessary; the objective is to make the curve a smooth one. The rear vertical bit has a very slight bend in it which has defeated my efforts at correction, but painted I don't think it'll be noticeable.

 

I went back and cleaned off the excess solder next to the beading, using a sharp knife (chisel type blade) and wet-and-dry. The nice thing about 188 solder is that excess can be carved away quite easily. Since the pic was taken I've gone back and done a final tidy-up.

 

The two things down on the left are the sandboxes, each made up of a single fold-up etch.

 

Nigel

Edited April 22, 2017 by NCB

[NCB]

I've also added the coal-rails to the bunker top, and supports for the roof to the top of each cab side:

 

 

Not visible, bit I've drilled pilot holes in the tank tops for fittings, namely water-filler, vent and what I think is the injector for the top feed. This last is going to be interesting; can't find a casting anything like it. Will probably need to knock something up.

 

Nigel

Edited April 24, 2017 by NCB

[NCB]

Now for a bash at assembling the footplate steps, while waiting for the new etchings to come back. Here's the step etchings:

 

 

Each assembly has a main bit with a fold-up step at the bottom and a short tab at the top which fits in a slot in the footplate subframe. There's also a couple of small tabs at the top which fold outwards; these provide additional strength to the footplate attachment, and also help locate the half-etched detail layer which fits on top of the main bit. This detail layer really just adds the vertical flange part of each step.

 

Here's two steps assembled:

 

 

After bending up the bottom step and the top side tabs and checking the fit of the half-etch, the main bit was lightly tinned, the half-etch laid on top and held in position by an old pointed file, more flux applied, and the iron whacked on. Job done, except for the middle step, which needed its rear tab filed slightly so it fitted in the provided slot, before more flux and a dab of solder fixed it; it looks as though it's sloping in the pic, but that's an illusion.

 

The steps won't actually be fitted to the body until near the end.

 

Edit: Just done the other pair. Unfortunately, while giving the middle step a few brushes with a file so that it fitted, it took off into space, I know not where. I wonder how many lost bits are scattered around the room waiting to be found!!! However, I was in luck; Brynkits do a useful etch of bits and pieces including steps, and one was spot on :-)

Edited April 25, 2017 by NCB

[NCB]

The PPD etchings for the front bits should be on their way. In the meantime, have formed the cab roof:

 

 

I normally find this sort of thing goes easily, just shoving it through rolling bars then just a bit of tweaking. This one was reluctant! Maybe the nickel silver was a hard variety. In the end rolled it using tubes on a bit of old camping mat. Worked sort of, but the result was a mish mash of different curves. However, using small pliers with flat faces I managed to reduce the curves to something which fitted.

 

The rainstrips on the edges on the other hand were dead easy. I'd half-etched these on the underside of the roof, and by sticking the half etch in bending bars and pressing the roof back they formed quite nicely.

 

For a bit of light entertainment, took a pic of the loco outside the engine shed of my slowly developing 3mm layout:

 

Edited April 28, 2017 by NCB

[NCB]

Etchings for the bits around the smokebox back from PPD. Here they are (sorry about them being a bit out of focus):

 

 

The non-prototypical joggle in the side frames is to make sure they keep clear of the back of the front drivers. The side frames sit directly above the chassis frames, which are also a bit narrower than prototype (explained earlier).

 

Here are the bits in place. The front bit was curved to match the side frames and trimmed slightly before being attached.

 

 

Meanwhile, I've ordered plates for GWR No. 33, the last survivor of the class which was withdrawn in 1951, from Guilplates.

Edited May 2, 2017 by NCB

[NCB]

Bit of detailing at the front. Added the two sandboxes:

 

 

These add a useful bit of stability to the splashers, which were a bit delicate.

 

Also added the steps to the front of the tanks, and the front buffer-beam lamp-irons, This is the sort of job I hate, soldering little bits onto the body when there's no positive means of locating them. Managed it eventually, although the lamp irons aren't the strongest. It's possibly one of those instances when a stronger solder than Carr's 188 would be an advantage.

Edited May 6, 2017 by NCB

[NCB]

Been otherwise occupied for the last few days, but managed to squeeze a couple of things in. First the coupling hooks:

 

 

And a look at the rear end of the engine for a change!  Not the best pic to show the hooks. Each is an etch which folds back on itself to double the thickness. Holding the rear with pliers, solder is run round the edge, followed by a bit of shaping with a file. Bit more fettling to make sure the tail fits the slot in the buffer beam, and also doesn't project behind the beam (would interfere with the chasiss if it did). Then soldered in place from the rear; this minimises getting solder on the buffer beam.

 

The other thing was to start sorting out castings for fittings, mainly from the 3mm Society's generous collection of such things. This is so that where necessary holes can be made or enlarged in the locomotive body to take them, before the final more delicate bit of soldering for details such as handrails takes place. Here's the tentative selection so far:

 

 

Think these are close enough, maybe with a slight bit of modification. The major omission is the dome; not happy with what I've dug up so far. I have one dome I'm attempting drastic surgery on, but not sure how it'll end up. If all else fails, I'm in the process of getting to grips with 3D printing, and that may be the answer.

 

The 16BA bolt and nuts on the right are the basis of an attempt to produce the injectors. The components are about the right size, so I'll see how it goes.

[NCB]

Had a shot at producing an injector:

 

 

Needs a bit of cleaning up, but seems the right size and proportions. The basis of it is a 16BA bolt and 3 16BA nuts. The vertical bit is 1.1mm micro-bore tubing. Forming a hole through the tube to take the bolt was easier than I expected; I started making a horizontal cut with an Xacto micro-saw blade, until a hole appeared in the tubing wall, then used a 0.7mm drill to bore through.

 

Now run out of 16BA stuff!  So ordered some more, for the other injector.

[NCB]

Couple of slight problems. In attempting to finish off the above a nut unscrewed, and the whole thing rapidly became a disaster of solder and metal. Also, having ordered the 16BA stuff from Squires along with other stuff, the order arrived with the 16BA stuff missing (out of stock).

 

Never mind; such things are there to challenge us! I have thought of an alternative way of doing the injector which may be better. May...

[NCB]

The injector, Mk. 2!

 

 

This may do it. The vertical bit is still 1.1mm microbore tubing. For the horizontal bit I used 0.8mm microbore tubing as opposed to a 16BA bolt. 0.6mm nickel silver rod for piping can be run through the tube, as seen, which saves having to try to attach the piping after the injector has been finished. The 16ba nuts were replaced with 3mm Society round 14BA nuts used for crankpins; these are no larger, and are a tight fit on the 0.8mm tube which helps getting things right with soldering.

 

After knocking this up it was a matter of minutes to do the one for the other side.

 

Each tank top now needs the pilot hole for the injector enlarged to 1.1mm to take the vertical bit, and the 0.6mm rod bent to the right shape for the piping. With the previous effort I'd cut the 1.1mm microtube short and shoved in a 0.7mm spigot for mounting it, but for this one I don't think I'll bother.

 

Getting there, I hope!

 

[NCB]

Injectors now fitted, on top of the tank, and the connecting piping bent up from 0.6mm nickel silver wire, as previously indicated:

 

 

 

Went relatively easily. Getting the bend in the right place where the piping ducks under the boiler cladding was probably the trickiest bit.

 

Please with this; knew it was going to be one of the more challenging bits. The remaining soldering should be straight forward (optimist!), namely finish the lamp brackets, add the handrails, then the footplate steps, also finish the cab roof.

[NCB]

Rear lamp brackets now attached. I'm not enthusiastic about soldering up small bits of folding metal and then soldering them to the body, but managed this OK.

 

Edited May 30, 2017 by NCB

[NCB]

Now the handrails:-

 

 

 

 

The handrails are made from 0.4mm nickel silver rod, and the handrail knobs are Markits N scale. The holes in the knobs need opening up just a tad with a 0.4mm drill, a miniature broach, or both.

 

Next job is attaching the steps; after that there's 2 or 3 minor soldering jobs to do to complete the soldering.

[NCB]

So to the steps:

 

 

 

The main complication was due to me soldering a rear step to the front. Doh!  With solder then where I didn't really want it, it made attaching the front step in that place more of a hassle than it need be. The tab-and-slot method worked fairly well, although I had to reduce the height of the tabs slightly because the footplate top was behind the slot. Next time I'll etch the tabs about half the thickness of the metal, and make the slots just a tad longer to make sure the tab goes in easily.

 

I have the roof to add the ventilator top to, and smokebox door darts to solder up, and that's the end of the soldering. I'm off on holiday next week, back early July, so reckon things will probably have to wait.

[ChrisN]

I have said before in other places that I dislike posting when I have nothing to add to move the thread along, and some threads are awash with 'ohh, isn't that brilliant'.  This post will not move it along as you are doing that and it is a shame that there has been no, 'ohh isn't that brilliant,' because it is.  Modelling of the first degree.

[NCB]

I have said before in other places that I dislike posting when I have nothing to add to move the thread along, and some threads are awash with 'ohh, isn't that brilliant'.  This post will not move it along as you are doing that and it is a shame that there has been no, 'ohh isn't that brilliant,' because it is.  Modelling of the first degree.

Chris, the odd Like will do for me!

 

I hate soldering brass; nickel silver is so much easier. I've built a fair few kits, but mostly ones shot down to 3mm from other scales and that often means problems which need working around. Getting into CAD and etching is a massive step forwards, being able to produce something you know should work. Next step upwards is getting into 3D printing.

 

Nigel

[Y Ddewin gwyn]

Like doesn't quite cut it. A tour de force. Hwyl fawr

Edited June 15, 2017 by Y Ddewin gwyn

[NCB]

Refreshed by an extended break in Scotland, clobbered by a subsequent scheduled op, which wasn't too bad but the aftereffects are still kicking around, I am ready to return to the fray. I'll be easing myself in gently; don't know if anybody else finds this, but I find it hard to model in summer evenings when it's still light outside.

 

First task is to complete the cab roof, by adding the top to the small ventilator at the front of the roof:

 

 

As etched there's a couple of small tabs to each side of the hole in the roof which were intended to bend up and locate in etched grooves in the top. However, I realised it was going to be difficult to do without distorting the roof, so instead I soldered a couple of bits of 0.6mm nickel silver wire into the grooves in the top, and then soldered that to the roof. Needs a bit of a clean up. The holes in the top are for whistles.

 

The idea is that the roof will be painted separately from the engine, and then as a final move glued to the cab; this allows the cab to be painted easily.

Edited August 7, 2017 by NCB