Locomotive Building Challenge

I’m not sure how it happened but I’ve managed to rope myself into building a locomotive in competition with a friend of mine Bruce Woods. We were swapping posts on the Yahoo! group 7mmAusmodelling when I mentioned that I was considering scratch-building a NSWR 20 class locomotive. Bruce replied by asking me why I would think of doing such a silly thing when the KRM NSWGR 20 class locomotive kit is on the verge of release. My response was that I would be willing to wager that I could scratch-build a 20 faster than he could if he waited around for the kit to be released. Bruce replied that he was more than willing to take me up on that wager. The one who comes up with an operating 20 class in 7mm first gets lunch bought for them at the following Aus7 Modellers Group Forum held at Sydney’s North Sydney Leagues club. You can see a photo of the two of us here at the most recent Aus7 Forum. Don’t let Bruce’s gentle, smiling exterior fool you: he’s a hot-shot when it comes to loco building and he works fast, so I’m relying on Keiran to drag the chain a bit on the release of the kit because once Bruce gets his hands on it I reckon I’ve got about 6 weeks!

If you’re wondering what a 20 class looks like, for those of you silly enough not to be modelling the NSWR in any scale, here is a photo of one:

This photo shows 2029 in revenue service. This loco is preserved at the NSWRTM at Thirlmere, south of Sydney.

This photo shows 2029 in revenue service. This loco is preserved at the NSWRTM at Thirlmere, south of Sydney.

The 20 class was ubiquitous on the Morpeth line in the years leading up to the line’s closure, hence my interest in having one. I’d planned to build a loco from a mix of scratch-built and kit parts from a Century Models 19 class well over a decade ago but had put the project on hold in expectation of the kit being released. As the years have dragged on the project went back on the burner, but it was only recently that I started to seriously consider actually making a start. Rebuilding Pioneer was meant to be a test bed for the building of the much bigger 20 class. As I’ve now finished re-building Pioneer I don’t have too many excuses to put off building the 20. Challenging Bruce is just a way to spur myself on to make a start. If I end up being beaten to a completed loco that’s ok but I’m going to give him a bloody good run for his money!

When I say I’m going to scratch build a NSWR 20 class I should probably be a little more precise: I’m going to do what I planned all those years ago, build it with a mix of scratch and kit parts. What I didn’t tell Bruce was that I already have in storage about 80% of the parts I’m going to need to build the loco including the wheels, motor/gearbox, detail parts, a set of etched side rods, hook draw gear and NS in sheet form to make up the superstructure of the loco:

This week I got out the box of parts and the 1:43.5 scale plans I have for this project. I started an inventory of the parts I had on hand to see what I will need to make and what I can use from my stash.

This week I got out the box of parts and the 1:43.5 scale plans I have for this project. I started an inventory of the parts I had on hand to see what I will need to make and what I can use from my stash.

It turns out that I have quite a lot of what I need but there’s a lot to make and I still need to do some shopping and internet searching before I can say I’ve got all the materials for the project.

My rough plan is to construct the following components using a range of materials and techniques:

– The chassis will be built using various (appropriate) thicknesses of nickel silver sheet. I will print out a paper pattern for the frames and glue this to two sections of NS sheet. I’ll tack solder these two pieces together and cut them out as one, thus giving me two sides that are exactly the same. I’ll cut slots for sprung horn-blocks on all three axles and this time I’m going to use Hobby Holiday’s ball race axle bearings. I’ve never used this system before and I have one or two reservations about it – mostly to do with the long-term suitability of such tiny, delicate ball races in a relatively dirty model railway environment – but I’m looking forward to the experiment never the less. I’m currently trying to decide whether I want to apply the rivet and bolt detail to the frames themselves or via an overlay of thin NS or styrene. I’ll make the leading and trailing trucks from a combination of brass and NS.

– The footplate, side tanks, cab and roof will be formed from NS sheet. While I’ve heard a lot of people say over the years that a Century Models 19 class kit could be used as the basis for building a 20, I have my doubts about how practical this is as a plan. If you bought a 19 class kit to build a 20 it seems like a lot of money to pay to get a small number of details to me. I’ve decided that it’s simpler to scratch build these parts from raw materials than try to kit bash parts from a 19 class kit. I will use parts I have from a 19 class kit, kindly supplied to me over the years by Peter Krause, recent past proprietor of O-Aust kits, where appropriate. The front splashers, sand boxes and a number of other details should be useable, but I’ll make a decision on these as I go and if I think I can make more accurate versions myself, I’ll be doing so.

– The smoke-box and firebox will come from a Century Models 19 class kit but I’m going to form the boiler from a length of pvc waste pipe. In measuring the boiler of a 20 from the plans I have it turns out the kit’s boiler from the 19 class is about 2mm under-sized, so I’ve made the decision to go with the pipe. The length I’ll be using is exactly the right diameter and it will be easier to machine the slot I’ll need for the Slaters motor/gearbox combination than it would be on the cast 19 class boiler. The dome and stack will also be 19 class parts I already have on hand.

The real irony with this loco build is that I’ll be using a couple of KRM parts from Keiran’s 20 class kit project that he’s had available for retail sale for quite a while now. I have a steam whistle and some injectors for my 20 class, and very nice parts they are too. However without a loco to attach them to they’re not a lot of use to anyone, except someone like me who is silly enough to bet I could scratch/bash a loco before two of my modelling friends could a) produce a kit and b) assemble a locomotive from it. I told Bruce I didn’t think it would be fair if he got parts from Keiran before the release of the full loco kit: in other words I don’t think he should start his build till the kits were generally available. I didn’t say the same should apply to me though 🙂

Game on Bruce!

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