Nick Mitchell

I'm very very slowly building a layout based around Healey Dell viaduct and Broadley station on the Rochdale to Bacup branch of the former L&Y. I haven't made much progress yet, and I've got the excuse of the 2mm Association's Diamond Jubilee Layout Challenge to distract me from making progress in the next couple of years...

I have at last got round to finishing off my L&Y Radial Tank, with the last few bits of boiler furniture. This one started life as the final test build (out of several) for Nigel Hunt's kit, and has been "almost finished" for ages. After N Brass produced the cast chimney earlier this summer, I was spurred into making a dome and safety valves to go with it. Once I've painted it, I can make a start on the Belpaire boiler and long bunker versions...

If only all etch designers went to these lengths to ensure their kits went together accurately and as intended! I am very much looking forward to building one of these when the final version is released... but please take your time with this one Nigel. You're releasing kits far faster than I can build them... As it happens, on my workbench at the moment is another one of Nigel's confections. 8 years into the build (I've been building other things as well - equally slowly), and the list of details still to be added to body and chassis is getting worryingly small as the inevitable trauma of trying to paint and line it draws closer. Nick M.

Hi Jerry, Richard, I'll take some pictures when I can, but it's probably clearer to see how it goes together in the sketch attached below. Some of the bits are truly tiny, and soldering to the decoder is certainly not for the feint-hearted. At least on the DCX77 the solder pads are at the edge. I feel slightly nervous that I might be encouraging people to destroy their expensive decoders! They don't necessarily blow up when you ruin them... they can just make a slight smell and stop working. Yes, this is the voice of bitter experience - you don't get much in the way of pyrotechnics for your 30 quid! The procedure I followed was: Read Nigel's article on the 2mm Association website thoroughly (it includes a circuit diagram). Follow his example and file a pointy soldering iron bit to an even smaller point. It has to be at least as narrow as the pads on the decoder!!! Tape the decoder securely to the desk to work on it Tin the pad from the iron (At first I tried putting a crumb of solder paste on the pad with a cocktail stick, then heating it. While this "worked", it spattered everywhere and needed careful cleaning up. Better not to need to do this.) Tin the wires. These were spare bits of wire I'd trimmed off other decoders in the past and saved. Leave them long for now so you can thread them more easily through the loco - only trim to length when the decoder and stay-alive unit are physically installed and it is time to connect them permanently. Hold a wire in position with tweezers (as close to the end as possible) and touch with the iron. This is the hardest bit. You have to hold the iron a comparatively long way from the very tiny tip. I have reasonably steady hands, but it looked through my magnifier like I was shaking violently when I was doing this. The "standard" colours for these wires are blue for the common positive (some decoders have this already, but the tiny CT ones don't) and black with white stripes for the negative. Check VERY carefully with STRONG magnification that you haven't made a solder bridge from the pad to any other component. Assemble the stay alive components, and check several times that the polarities are correct TEST the decoder still works before connecting the wires to the stay-alive circuit. Install the decoder in the loco and test again. Assemble the stay-alive circuit, and chek at least 3 times against a circuit diagram that the polarity of the components is correct. Connect the stay alive and test yet again. Crack open the Rizla paper and show off to your friends. Some additional points to note: Tantalum capacitors are polarised. SMD capacitors have a stripe to identify the positive pole. (The opposite of non-SMD Electrolytic capacitors which have a stripe to denote the negative lead - just to confuse!) If you connect them the wrong way round, tantalum caps can explode more spectacularly than a decoder... be warned! Make sure the capacitors are connected in parallel. You get the sum of the capacitance this way. If you connect them in series, the total capacitance is reduced, but the voltage increases, and will kill your decoder. The Mini-MELF diodes have a band at the cathode end (same as regular diodes) and this is colour coded according to what type of diode it is. Schottky diodes have a grey-ish blue band, and Zener diodes have a blue-ish grey band. Something else to get confused about! If you forget to disable DC running on the decoder before you connect the stay-alive, you'll have to un-solder it before you are able to alter any CVs. In my experience, CT Elektronic decoders don't like high track voltages anyway, but it is worth checking that your DCC system is not putting more than 16v on the track. (If you're reading this and want to build one of these for a larger scale, I would recommend using 25v capacitors - they're bigger, but you'll have room!) The components I used are as follows: Capacitors: 16v 220uF Tantalum chips, case D - also known as 7343 (metric) and 2917 (imperial) 10PCS 7343 Case D 220uF 16V 7.3x4.3x3mm SMD SMT Tantalum Chip Capacitors | eBay Zener Diode (to prevent over-voltage to the capacitors): 16v (to match the capacitor voltage) 1W 20x ZMD16-DIO Diode Zener 1W 16V SMD MiniMELF tape ZMD16 DIOTEC SEMICONDUCTOR | eBay Schottky Diode (to protect the capacitors from reverse voltages - I chose Schottky because the voltage drop across the diode when the caps are discharging through it is significantly lower): 40v (not critical) 1A (needs to be at least as high as the rating of the decoder) 20x SGL1-40-DIO Diode Schottky rectifying 40V 1A MiniMELF SGL1-40 Carbon film Resistor (to prevent the DCC Command Station seeing a charging capacitor as a short circuit): 100R, 0.25W 50x SMDMM0204-100R Resistor carbon film SMD 0204 minimelf 100Ω 0.25W ±1% | eBay Have fun if you decide to make one, but don't blame me if your loco blows up!

You were right about the dome, Colin! My coal tank now has a new turned one which I'm much happier with. Those who subsctibe to the 2mm VAG may be aware I've been experimenting with DCC Stay Alive over the last couple of weeks. I have managed to squeeze four 220uF tantalum chip capacitors into the empty bunker of the Coal Tank. The capacitors are arranged in a block, sitting on a rectangle of thin PCB, which rests on the frames above the radial truck. Once I'd added the necessary diodes and resistor, the block was wrapped in Kapton tape. I cut away the bunker floor, for the capacitors poke up into the coal space. They will eventually be completely covered by the toolboxes and coal. The running was good even before I added the capacitors, but there were occasional stalls - inevitable with a short, light loco. Even this comparatively tiny amount of stay-alive has taken the performance up another notch (once Nigel Cliffe helped me by revealing the secret that the decoder needs to have DC running disabled). This is how I want all my locos to perform. Here's a little video showing it doing its party trick: https://youtu.be/NcxEq_deKBI You may notice I've still got some bits of insulating tape preventing the front guard irons and brakes from shorting.

I spent a pleasant few hours this afternoon making a new chimney - turned using hand gravers and files in my watchmaker's lathe. The attached photo shows the result in company with the rather corpulent casting it will replace.

After my last progress report I took a break of several weeks from all things Coal Tank. Having been treated to the sight of Nigel's superlative model "in the flesh" last weekend, however, I have been inspired to get moving again, and below are some pictures showing where I'm up to. The chassis has been completed with the addition of the brake gear... and it even still runs! One refinement to the mechanism I am considering is filling part of that huge empty bunker space with tantalum capacitors as a "stay alive" circuit... if I can solder the wires onto the decoder. Nigel's warning about needing to bend the brake hanger wires down so that the coupling rods don't hit the brake pull rods was useful. Bizarrely, I only needed to lower them on the right hand side. The brakes hangers for the middle wheels had to be attached to the frames ahead of the bearings for the gear axle and cranked to hold the brakes in the correct position. I hope this is clear in one of the photos. The real fun and games came when adding the pull rods. There are holes in the frames to attach the cross-rod for operating the pull rods. Unfortunately, these are behind the flanges of the rear wheels! This may be a feature of the etch-shrinking process, but left me scratching my head. I thought about bending the shaft round the wheel flanges, but in the end settled on soldering it to the back of the downward protrusions from the main frames that had the holes in them. Missing altogether from the kit are the cranks that connect said cross rod to the ends of the pull rods. The scrap etch box came to my rescue here, and I found some suitable little cranks left over from some long forgotten wagon chassis. Because the cross shaft is set further back than designed, the cranks look to lean back somewhat more than they should, but I think this it the most pragmatic compromise. Ideally the pull rods should be longer, but I wasn't up for making new ones or attempting to extend those in the kit... I consider myself lucky to have got away without mangling them as it is - they are so thin and fragile. Now I am left with the problem that when I place the body on the chassis, the front brakes are squashed tight up against the guard irons. There should be a gap between them - on the real thing, the front sand pipes go down this gap. I'm not sure at this point whether to try and file the guard irons thinner, or cut them off and try to attach some new ones further forward on the frame extensions. I think the latter course of action would probably look best. Speaking of the body, only a little progress has been made here. I cut the boiler tube to fit over the motor. A 5 thou shim was added at the smokebox end, with the rivetted wrapper fitted on top of that (top half only soldered at this stage). The wrapper was fitted protruding 8 thou. so that the front plate could fit inside it later. This wrapper, incidentally, is from a different shot-down LRM etch I've had in the gloat box for ages - I think two of them might come with a Bowen-Cooke tender! Anyway, after poking out all the rivets on the smokebox front plate, a horizontal bend has to be made under the bottom of where the smokebox door will be. The cylinders of these locos are inclined, so the front of the cylinder/valve chest needs to be perpendicular to them. In many photos of coal tanks there is a noticeable "crease" across the front, so it is worth replicating. Unfortunately, in these photos of mine, it doesn't seem to show up at all! I attached the handrail to the smokebox front before fitting the front plate to the boiler tube. It was necessary to file some notches in the boiler tube to clear remains of the tails of the handrail knobs (association etched ones). I didn't want to file these completely flush in case they came adrift. For once I had thought ahead and filed the notches before adding the smokebox overlay... Once the front plate was in place, the bottom part of the smokebox wrapper could be formed around the reverse curves and soldered in place. I found this bit particularly tricky to get right. The smokebox door is my own turning. I started off with the N Brass one, spent ages thinning it, then decided it was still too big (it was covering the rivets) so I determined to replace it. I hope I have captured the subtle dished shape of the prototype, but in these very cruel pictures I can see that I haven't polished it enough! I have to say I'm a bit disappointed with all of the N Brass castings for the Coal Tank. Other castings I've bought seem much finer (a chimney I've recently acquired for my Radial tank, once polished, was first rate). The chimney and dome in the photos are just loosely balanced in place to give an impression. I think I am going to have a go at turning replacements for both of them. The chimney especially looks a bit portly, and the casting has some flaws in it (a chunk missing from the rim, corners missing from the base) that might be just as difficult to correct convincingly as turning a new one. The dome looks a bit lumpy too - but then I'm sure a real one after 60-odd years service would have its fair share of dints. I'm basically at the stage of adding details now, which is where most of my loco projects seem to stall - the last 10% of construction seems to take 90% of the time. That said, not much of the first 90% of this one has been easy, but I'm really pleased with how it is coming along.

Some stainless steel coupling rod etches arrived from Shop 2 yesterday. The word on the street is the artwork for these items has gone AWOL, so the nickel silver version won't be coming back into stock soon. Coupling rods really need to be thicker than 10 thou. I had no joy soldering these together in pairs, so in the end superglued them, which seems OK so far. I've installed one of the new "Long format" CTelektronik DCX77 decoders in the ash pan (picture below). I didn't know these existed until I was offered the choice when I went to buy one. The original plan was to mount the decoder on a plate sticking up into the bunker, but with something happy to slip between the frames, the bunker area can be kept clear. It might be nice to model it fairly empty of coal. On the track, things are looking very promising indeed. The link below is to a video showing it strutting its stuff. I had to blu-tack a b-t-b gauge over the centre drivers to calm it down. It really needs more weight than this, but there will be plenty of room in the tanks, smokebox, bunker and even a bit on top of the motor. https://youtu.be/wjlvwOrW-XM Just need to fit the brakes now to complete the chassis.

I thought I'd give an update on how things are coming along with my experimental Coal Tank chassis. Although far from complete, I'm now happy that using the supplied chassis (radial truck aside) is a viable option. I have had a few tense moments along the way, however! The pictures below show where I'm up to, but I have a few comments too. Despite my cunning plan to solder the radial cheeks for both frames as one piece while the frames were lined up and attached to the fret - guaranteeing alignment.... when it came to testing the truck in place, it was obvious that they were not anywhere near aligned! I don't understand how, but the radial axle leered at me from a jaunty angle. The beauty of soldered construction is that when things are wrong, you can take them to pieces and solder them again. Which I did, again with the aid of the "tool" from Nigel's 2-4-2 kit, and all is now well. The relative position of the cheeks was only a few thou. out, but the effect was that the chassis could never have run satisfactorily. The 8 thou nickel silver does make it rather delicate - one can't be too ham-fisted - as I found out to my cost, but with the spacers in place the frame seems pretty rigid. Once I had put the gears in, and the centre pair of driving wheels, I found that the gears were able to bind. I had allowed a bit of side-play on this axle, and with the Simpson springs taking up space, there wasn't quite enough room. You'll see from the "underneath" picture how I've since thinned the spur gear on the driven axle. To do this, I had to remove the wheels from the muff, and in pulling them out, I managed to distort one of the frames slightly. I suppose I should have melted the muff off, but the temptation to try and re-use it overcame me. I am normally to be found in the "tight muff" camp when it comes to fitting wheels, but after the ease with which I now know this material can be damaged, not wishing to court further disaster, for this loco I have adopted the "loose muff" approach. I will inject glue once the coupling rods are in place and everything is running smoothly. The frame was straightened eventually, and touch wood, bears no lasting damage. The motor (which I'm really pleased with) is simply epoxied to the long central spacer. The top of the spacer has been adjusted to be about 10 thou. below the top edge of the frames, and this gives an acceptable mesh for the worm. I found some pieces on the etch which I couldn't identify, and which I pressed into service as the backing plate for the (absent from the kit) front tank supports. Rectangular with a half-etched line down the centre, they were too long, but were easily brought down to size. I hope I won't miss them at some future point in the assembly of the body! Incidentally, the web of these supports is the wrong shape as supplied (for the two which are supplied) and needed filing to an inwards curve once soldered in place. An appropriate bit of the etch frame sufficed for the front support webs. You can see in one of the pictures the support I made for the back end of the boiler. This was turned, and pegged into the hole in the cab front. The bottom part of the cab front and a section of the floor has since been removed (which would have been much easier to do in the flat) to accommodate the motor. As can be seen, this protrudes just over 2mm into the cab, but is fairly unobtrusive I think. At the front end, all the mechanism is contained within the length of the tanks, and especially with the weighshaft and balance weights in place, should be well hidden. Now I know exactly how far the worm extends, I can go back to the upper works and make the necessary cut-outs in the boiler tube. I am planning to use the Association coupling rods (from the generic etch). The ones supplied have too many things I dislike about them. They are meant to be jointed, which is difficult to make work and look good in 2mm scale - especially with built-in slop in the axles. They are also far too chunky (which is not an insurmountable problem). But fatally, the holes are too big for the Association 0.5mm crank pins I have used. Fortunately, the Association etch has a pair of 14.5 + 16.5mm rods on it which are just right (fluted side hidden), but unfortunately they are temporarily out of stock. Still, I have plenty of other jobs to be getting on with.

Up until a couple of weeks ago, I was happily sitting back waiting for the Masterclass chassis to appear. A conversation with that ever-so-persuasive Mr Hunt convinced me there was nothing to loose in having a go with the shot-down LRM bits in the mean-time. So far, it is working out quite nicely... The radial truck was always going to be the tricky bit, but I had a spare one from a test-etch of Nigel's L&Y 2-4-2T kit. I used the "radial cheek setting tool" from that kit to help solder a pair of 1.5mm wide n/s strips to the inside of both frames while they were paired up back-to-back on the fret. On the 2-4-2 kit, the cheeks fold in from the frames and the slots in the tool hold them at the correct angle while you put a fillet of solder in the folds. Here, they held the cheeks at the correct angle and spacing, and I positioned the pair by eye to line up with the bottom of the frame extensions. After cutting out and separating the frames, I cut back the cheeks to a sensible length, fitted some frame strengthening plates across the tops of them, and then filed out the horn gaps. For the drive train, I turned again to the Radial tank for inspiration. I decided to use the same gearing (21t worm wheel and 20t / 14t spur gears) giving 30:1 overall reduction, driving onto the centre coupled axle. For the motor, I intend use a coreless 719 - superficially identical to the current Farish ones, but obtained from eBay at £5 for four! If they turn out to be rubbish, a genuine Farish will substitute. A Nigel Lawton 8mm coreless would also fit. Fitting bearings for the intermediate gear axle caused some head scratching. I'd initially thought about using a section of the frames from the aborted 2-4-2 teat etch as an overlay to the inside of the main frames, but then thought better of it. In the end, I used them only as a template. I used an Association gear meshing/marking tool to measure the meshing distance in the 2-4-2 frames, and mark out an arc on the Coal Tank frames. The hole for the bearing was going to have to break out of the top of the frames, ending up as more of a slot in which to fit the bearing. I made the slot slightly too large (deliberately!) and then with the driving axle bearing soldered in place, used the meshing/marking tool as a jig to hold the intermediate gear axle at the correct meshing distance as I soldered it to the frame. Nigel H sells a set of generic etched frame spacers, to be used with thin double-sided PCB. I had a set tucked away and they were ideal for this little project. You can see where they ended up in the photos below. I used more spacers than one might normally expect, in an attempt to make the thin frames a rigid as possible. I think I have succeeded in that respect. I even went so far as to make one spacer into a representation of the motion plate, and added suggestions of the top slide-bars and valve spindles. These will be practically invisible under the boiler, but were fun to make. After installing the spacers, the front and centre driving axles have been opened out to 1.6mm for Simpson springing. Springs and some cosmetic detail has been added. The kit only has provision for a single tank support bracket each side. I understand there should be another pair near the front of the tanks. They may end up being hidden by the steps, but I will probably have a go at fabricating them from scrap etch anyway. I haven't fitted rods for brake hangers yet, as I intend to use the Association wheel quartering jig, which they would foul. Besides, one of them ought to be positioned right on the flange of the intermediate gear axle bearing. Not sure how I'll surmount that problem yet - maybe a cranked hanger, or maybe even no hanger with the brake fixed only to the pull-rod at the bottom. The photos below show: 1. My method of holding frames together with Association frame jigs in a vice to solder the spacers in place. The spacers were previously soldered to the RH frame - top in the photo - and checked for square-ness. You can make out a Fence Houses spacer wedged in to keep things square where the frames are particularly vulnerable. 2. Checking from every angle that the frames are parallel and square to each other. 3. A rough mock-up of where the gears and motor will end up - hopefully well hidden. The back end of the motor will protrude into the cab by a couple of mm, but shouldn't be visible from most angles. There should be plenty of space for a decoder in the bunker, and the side-tanks and front section of the builder will fill with lead. A good chunk of lead should fit in the ash-pan too. 4. Once the boiler is in place, the motion plate etc, won't be visible. This shot is to prove the bits really are there! 5. The chassis as far as I've got with it - springs fitted and details such as tank supports and life-guards fitted. The springs at the rear will engage in eyelets on top od the radial truck to provide centre springing and some down-force. (It is necessary to have two springs, as experience has shown the trucks will tend to rotate around a single one.) I'm posting this now, as it is the happy point before I put in the wheels, gears and motor, and find it wobbles or binds or won't go round corners... Nick.

If you're going to do a GWR loco, Nigel, how about one of the "Improved Castle" class that the LMS contracted North British to build for them? On the subject of spacers, I too was apprehensive of this kind until I plucked up courage to give them a go. I think I actually prefer them now, as you can make them look more like the frame stretchers on the real thing - especially if you can see under the boiler and between the frames. The key is to make sure you hold the frames dead straight and rigid while you solder them in. I solder all the spacers to one frame first, while the frame is flat. It is easy then to check that they are soldered square to the frame, and adjust if necessary. To fix the second side in place, I use the association jig, holding one end of the bobbins in a smooth-jawed vice (one of the watchmaker's ones from Shestos), with the frame lying flat on the top of the vice jaws. Theoretically, this means the frame can't bend or twist. Nick.

While useful background, I found that most of the 4mm instructions didn't apply at the "ground level" in 2mm, so I started writing up my own construction notes as a set of "alternative" instructions for the body. They only go as far as I've got with my build, but I have attached a copy of my working draft, in case anyone wants to follow exactly what I've done. I will update them once I've got the chassis built and know how to finish off the body. Coal Tank 2mm construction notes NPM.pdf

I made a start on mine when it arrived, but it is currently on pause awaiting the availability of the Chris Higgs chassis. There are some photos below showing progress to date. I deviated substantially from the instructions and had to modify a few parts to get this far. I would call this kit "difficult" when compared to others I have half built(!) but I am pleased with the way it is coming together. I haven't gone any further with the boiler and smokebox (which is the next step), as until I see how the motor fits, I don't know how much of the underside of the boiler tube to cut away. When I do get round to the smokebox, I intend to form it in the same way I did the L&Y radial tank (Nigel Hunt kit) smoke box. There's a photo of this on my Gallery. Basically, I rolled the wrapper to be a tight spring fit. I spread solder paint on the top half of the inside of the wrapper and soldered it in place with a gas flame. The bottom edges of the wrapper (which remained unsoldered) could be peeled back and rolled the other way to match the profile of the smokebox front plate. While there is no etched wrapper in the kit, a suitable one forms part of the previously available shot-down Brassmasters etch for a Bowen Cooke 3000 gal. LNWR tender. (Perhaps that nice Mr Higgs could be persuaded to include one on the chassis etch?) At the moment I am debating with myself as to whether a 5 thou. "inner wrapper" should be installed, level with the front of the boiler tube, then the outer wrapper placed on top, projecting forwards by 10 thou. to fit over the front plate. If only a single wrapper were used, the front plate wouldn't fit inside it, and would have to butt onto the front of it.