Beardybloke

I've produced some inserts from 30thou styrene; narrower hole to fit around the axle, wider one to aid the impression of holes in the right place through the wheels: Seems like there's a chance it won't look completely dreadful, once some filler's applied around the outer edge (my circle cutter will only go down to 10mm diameter and these need to be 9mm) and the tyre rim is sanded away from the overlay. It'll still look small though, due to the small crank throw, and I'm wondering if I can make up a jig and make up a full overlay from styrene too. Might give it a punt and see how it looks, I've got the Backwoods ones to use as a template!

I should add that well-designed kits running on their own chassis don't have this problem; also, if I'd just been prepared to accept the undersized wheels, this wouldn't have been a problem either! The issue appears to be twofold - by fitting the bearings inside the chassis frames and so having to slim down the gears, I've left less material to support the stub axles thereby leading to a broken axle effect. On top of that, it turns out that araldite doesn't work on this material (moulded Acetal, apparently) so it's no wonder it was reluctant to set in place. I do have some wagon wheels (designed for 7mm/ft (1/43.5) narrow gauge) I bought with a view to converting them for use on a scratchbuilt loco. It seems that with the overlays from the kit and a bit of packing, I might get away with it. There are two issues: I'll need to rework the electrical pickups as they're currently able to pick up current from the whole back face of the wheel, but these ones only have metal tyres (which will completely miss the pickups as they are now). The axle diameter is 2mm, and I've just fitted a 1/8" (~3.2mm) bearing; I'll need to source some sort of insert... I could just scrap it and walk away, but I'm allegedly an engineer - I've got something to prove to myself here...

I'd say a masterclass in bodging at the moment! Fitting the new wheels is proving difficult as they don't want to sit true and parallel to each other. I can see a rethink, either by fabricating a drop-in axle from them and the gear, or by fitting a completely different set of wheels on a proper axle rather than stub axles...

The brass bearings have arrived and I've made a start at upgrading the bogies, the first step being opening out the original holes in the sides to take them; this was done with a couple of drill bits (gently twirled by fingers) and a series of tapered cutting broaches. Because of the thickness of plastic involved and a need to not clamp anything in a vice so as not to distort anything, this has resulted in some rather sore fingers and thumbs! It was already fairly apparent from the size of the bearings when they arrived, but opening out the first hole confirmed that they were far too deep and set the back-to-back dimensions of the wheels (the critical dimension for ensuring that a rail vehicle will correctly run through points, check rails etc.) way too far out, as can be seen by comparison with the original axle: The obvious (only) solution was to thin down the shoulder of the bearing, done with a swiss file: And then fit this from the inside so that it doesn't push the wheels outwards. This then created its own problems for clearance of the final drive on the axle: Which had to be thinned down in turn, and the hole opened up for the wider stub axle on the replacement wheels. Finally, both stub axles needed shortening slightly as they're a little too long, but need some extra clearance too so that they remain electrically isolated from one another. Fixing the bearings in place with some araldite left me here - about an hour and a half to (mostly) complete one axle. I really hope this is worth it...

The wheels have arrived! The stub axles are longer and a larger diameter than those with the donor chassis, so the length needs cutting down ever so slightly. I've also ordered a set of brass top hat bearings, at the suggestion of a member of NGRM-Online who, when describing his conversion, said that if he did it again, he'd fit bearings. I think it's a good idea, as it should reduce wear and tear from metal-on-plastic contact when it's in use on the layout. The gears will also require reaming out to the bigger size and a very, very careful application of araldite to fix it in place without gumming up the works. Probably no progress until those bearings arrive, because as I'll need to connect the two chassis halves together with wires to the motor, it'll be easier to fit the wheels, cylinders and valve gear whilst the bogies are separate. Now that I've tested the drive train assembly with the original wheels and new motor, I'm happy that it works, so it's safe to say that if there turns out to be a problem, I should be able to diagnose it!

Still no wheels, but first thing's first - replacing the motor with a modern, hopefully smoother one. So I removed the motor from the donor chassis and pinched the universal joints off it for reuse: The more astute among you may note that there is something of a discrepancy in the length and diameter of the new motor shaft - hence the brass shaft adapters, and the next step: The flywheel and tweezers are in use as heat sinks, to try and avoid overheating the shaft and melting the innards of the motor before it's even fitted (the plastic baseplate can be seen inboard of the contacts between the motor body and flywheel). After a whizz with the slitting disc, the shaft was checked and found to be exactly the same length as the original motor, which was handy: At this point, I test-fitted it in the cast whitemetal kit chassis with the UJs and shaft adapters fitted: It looks to be the right length - bonus! However, what's not readily apparent from the photo is that there's a fair old bit of metal to remove from the chassis to ensure clearances - not just for mechanical reasons but electrical reasons too; the kit is built on the 'split chassis' principle and each half of the chassis is live in order to facilitate the transfer of power from the phosphor bronze pickups behind the wheels to the motor; the original motor has spring-loaded brass contacts that should pick up from the raised bit visible below the left side of the motor and an equivalent above on the opposite half, along with some clear insulating acetate for the frame. For this motor I'll need to clear space around it, insulate the metal casing and then solder some wires to the chassis - very, very carefully as the melting point of whitemetal is significantly lower than that of solder and I don't want a discombobulated T-1000 rather than a chassis... I've ground out the interior of the chassis with a mini drill and a milling attachment, but the light's dropped a bit too much for decent photos. What I did do was hook up some wires to the motor and test the polarity; contrary to what you may think, despite it being essentially symmetrical, there is a front and a back - or, rather, in FR parlance a 'top' end and a 'bottom end', and I need to hook up the power to the chassis (and thereby track) so that it goes in the same direction compared to my other locos for a given track power polarity. To do this, I used a highly sophisticated jig and my rolling road: I then started trying to fix this in place in the chassis, but managed to desolder the wires in the process as they were too thick and inflexible. A rethink is needed, along with some thinner wire, and possibly some labeling on the motor for top, bottom, fireman's and driver's side. Still, never mind - we're off the blocks!

Etches and replacement motor (complete with flywheel and adapters to fit the 1.5mm universal joints onto the 1mm shaft) have arrived: As it's probably a good idea to get the motor in and working with the original wheels and gear train in place before replacing the wheels, I think I've reached the minimum threshold for metal-bothering to begin. First steps - make sure that the motor will fit, and swap the universal joints from the RTR chassis motor to the new one - remembering to fit the flywheel first...

Thanks @dnl42 - I'll look into that! I've been trying LibreCAD and have got the hang of basic shapes and angles, but less so with complex shapes and compound curves. I'm sure I'll get there, just not necessarily within the time limit of this GB - I've got a longer-term plan for a scratchbuild using those scale wheels. A very kind member of the NGRM-Online narrow gauge railway modelling forum has just posted a suitable replacement wheelset to me completely free of charge - I definitely owe him a brew and a bacon barm or cake if our paths ever cross at an exhibition! Once these have arrived I'll crack on with the foundations - getting a working chassis is vital, as I don't want a 'shed queen'...

As part of my pre-GB work, I've largely discovered that what I know about CAD could be written on the back of a postage stamp with room to spare. As a result, I've called the kit manufacturer today and a set of replacement etches will be in the post this afternoon; I've actively been trying to source a set of replacement wheels that are between the kit ones and scale ones in size (so a compromise, but easier to fit); and I've also ordered a replacement motor which will hopefully lead to improved running. Beyond that - on the stroke of midnight tonight, I may well start carving away some whitemetal...

This is what it's hopefully going to look like. The kit itself is essentially a set of whitemetal cuboids and cylinders, hopefully of the correct dimensions! Pretty much all of the detail apart from the tanks, domes, smokebox, chimney and cab will need to be made from aftermarket etched parts or from scratch -this includes the valve gear and the unpowered leading and trailing wheel sets. The kit also has the earlier (1970s) cab profile that will need replacing in either brass or plastic to replicate this photo. So a fair bit of work ! I should add... This will be a working model! The chassis will be arriving today, apparently...

I may or may not have found that one of the small model railway suppliers does a set of etched Walschaerts valve gear for Mountaineer suitable for the Graham Farish outside framed Class 08 chassis. I can neither confirm nor deny that I have bought both of the items mentioned above.

With the gracious permission of our glorious hosts, last night I set about assessing the situation. I've got a spare set of wheels from an etched kit for the same loco, provided to me for free by the late Roger Christian (one of the 009 Society's greats, and a fantastic modeller) when he sold me a number of his unfinished kits shortly before his untimely passing - at a time when these kits were going for silly money, he was kind enough to sell them to me at the original RRP, as he believed I'd actually build them rather than stash them or sell them on. COVID, work, kids and a lack of courage have all got in the way of me starting this, but using the wheels is baby steps in the right direction. In fact, the De Winton has helped, as a big part behind the lack of courage is knowing that I messed a couple up in the past and they've been sat on the Shelf of Doom for 15 years. Anyway. Enough navel-gazing and exposition. The below photo, with the power bogie from one of those aforementioned kits of doom shown and one of the correct wheels left off for comparison purposes, should hopefully show why I want to do something about the wheels and why the missing etch is probably a blessing in disguise: The etched power bogie shows what we're aiming for. The issue with Backwoods kits (from whence this comes) is actually that they're probably too accurate - the cylinders have been spaced slightly wider apart to account for the slightly wider gauge compared to what it should be if it were true to scale (7.83mm vs 9mm) but probably not enough; the kits were (and remain) notorious in requiring the skill of a watchmaker to get them running. If this can be achieved, they are fantastic. I have 6 of them in various states of completion, and I will finish them one day. Designing these replacement parts may actually help me to do that. Sorry. Omphaloskepsis again. The RTR (that's 'ready to run' in this context, not the Chav Cav) chassis has a shorter bogie wheelbase and a shorter overall wheelbase, but the former is only by 2mm. This means that I should be able to use the basic dimensions of the 'proper' bogie to work out what an etched one for the Bachmann chassis should be. The coupling rods (between the wheels) are simple - the same dimensions, but subtract 2mm from the plain bit in the middle. In reality it may not be quite this simple as the ends may need to be slightly over-scale to accommodate a working crankpin, but this whole thing is a compromise and the priority is to get it running and looking right - it doesn't have to actually be right. Checking the length of the connecting rod (driven (rear) wheel to piston) showed it to be the same as the coupling rod to within about 0.1mm - perfectly acceptable over a 19mm length when accounting for the inaccuracies of the etches which were done from hand-drawn artwork (as opposed to CAD) around about the turn of the millennium, and when accounting for the fact that I may not have been measuring to the exact centre of the hole. If I can get the slide bars to sit at the same height relative to the wheel centres, simply cutting 2mm out of the connecting rod should work too. Hopefully from the picture you can see the absolutely minimal clearances between the back of the cast brass piston/crosshead and the crankpin on the front wheel - watchmaker territory indeed! Finally, a shot showing the chassis partially disassembled and the flexible drive from the central motor which allows the bogies to swivel: The diesel wheels are on stub axles and are a push fit into a gear/axle between the plastic frames, I'm hoping that it's going to be possible to widen the holes and install a 2mm axle for the wheels; this might require brass bushes in the frames to prevent the plastic from wearing and the whole lot coming to an untimely end. This chassis didn't seem to be the best of runners when I tested it - I think a clean and service is in order, and possibly sourcing a replacement motor. No point in it looking pretty if it won't run - this thing is going to earn its keep on a layout, if I ever get one built! Next steps, then (all legit pre-GB activities, I think): Identify a suitable CAD programme Draw up the parts (connecting rods, coupling rods, slide bars, crosshead and piston, motion bracket) Find a suitable source of laser cut or etched parts and get the parts priced up (and hopefully made) Source the other necessary parts (brass bushes, crankpins, washers) Clean up and test the chassis on my rolling road All of which might bring me to 0% started, if I get it done before 28th June!

Thanks Adrian. Now I just need to learn how to use CAD. I knew there was a flaw in the plan somewhere! (Actually I have used it before in a basic way but not since A-levels, which are now a very long time ago...)

Thanks Pat - it'll definitely be motorised, the only question is how good the wheels will look and whether I'll be able to source better coupling rods for it (I've heard that the manufacturer is pretty good about supplying replacement parts). I suppose that leads me onto a question for the hosts - @JOCKNEY, @Mjwomack, @AdrianMF or @2996 Victor - would you consider working on the CAD designs and trialling prototypes for the valve gear before the official start of the GB as being within the spirit of the rules? Given that I'm essentially replacing missing parts, I might not even be back to 0% complete by the start date, let alone close to the 25% limit!

Third rail for broad gauge? Yes, I see your point! Yes, I can imagine - as a youth I was probably a bit on the parochial side when it comes to railways. Possibly in part as my boss in the model shop was into his Swiss railways (real and model), so it was fun to wind him up despite the models being much, much better quality than pre-2000 Hornby... My eldest did enjoy it - she's a bit young for a forum account at 8 and a half, but I might well try and document our next build together on here. The youngest has enjoyed making some Metcalfe kits in N Gauge too...