New Zealand Railways A Class
The Light of Day
NZR A Class Locomotive

Northyard 1:64 Kitset
9th December 2019 - 3rd June 2020

The Story
At the moment I seem to be mostly building kitsets that my father bought over the years, but never started. He was a great Dad and I feel that finishing these models is a way for me to celebrate his memory by finishing something he always wanted to. He spent endless hours with me when I was growing up, and it's time for these models to see the light of day in their turn.

The Northyard A Class kitset was, from memory, a real step-up for those modelling 1:64th scale New Zealand Railways. The kit appeared on our living room table, some time in the '80s. Every few years, Dad would take it down from the top shelf where it lived, and peer inside at all the bits and pieces. The box become tattered with its many openings-and-closings, but it was otherwise untouched.

Last year, I decided to make a start on it. I was lucky enough to be sent a treasure-trove of prototype photos, including a lot of detail shots of the frame, the valve gear, the brakes, and piping. This amazing resource made me think I should put in some extra effort, and add more detail.

The kit could be beautiful right out of the box, but the loco frame was just a simple one-piece casting, with fixed axle slots. It precisely located the drivers and added weight, but I thought traction over uneven ground might suffer, and the solid block wouldn't look as prototypical as a plate frame. I'd never scratch-built a frame before but, what the hell...

The Build

The kit went together no problem, because it had been very well thought-out. Due to my usual impatience, I didn't follow the instructions exactly but, instead, flitted between the tender body, the boiler, the loco frame and wondering how many more details I could add.

Knowing when to stop
"It became a case of, the more you look, the more you see."
The kit frame looked different to the prototype in places, so I followed the drawing instead. I noticed that the model firebox was a lot longer than on the prototype, and that the frame under the cab had been narrowed-down to give more clearance for the trailing truck. Some of the frame attachment points were slightly different to the prototype and some were missing completely. I spent a lot of time figuring out how it should all work.

Once I'd made the frame, I worked through the rest of the kit, adding all the bits and refining them as I went. The mechanism ran perfectly smooth, with almost no tweaking.

It was a joy to build, and became a case of, "the more you look, the more you see". For example, I noticed that some of the steam piping shown in the photos had been lagged, and so I wrapped very fine copper wire to simulate the asbestos rope used on the prototype. I had some extra pipework fittings and used them to add pipe unions for more detail.

The sequence of photos below will show progress on the model much more clearly than my ramblings. Each gallery of images is more or less chronological, not counting the odd re-build, due to dissatisfactions or mistakes.
I originally planned to use Northyard bronze bearings in my new frame, but got talked into using roller bearings instead. That required a bit more work, but the end result was a much more smooth-rolling model. The front axle was sprung using NWSL Medium-weight springs and the two rear axles were equalised. To set the ride height, I made the equalising beams slightly over-height, and then carefully filed them down until the frame sat level.

It ended up running perfectly, and was worth the extra time spent figuring it all out.

Frame Upgrade
Scroll through the gallery below, to see the build sequence.

The first of my new roller bearing carriers.
I needed a way to hold the new bearings, so that they could be located in the frame. These carriers were the final result. The ones on the front axle had pins for locating coil springs. Filing each carrier to be a close slide fit in its matched guide was time-consuming, but worth it. All I needed to do next, was solder them in the right place.

It was a good system, but Lawrence from NZ Finescale has since made me a set of etched nickel-silver carriers based on my design which are much more accurate, locate the bearing better and don't take several hours for me to make...
I wanted to get the chassis running as well as I could before starting on the boiler, but failed. I was too impatient. I wanted to see how the rest of the model would look when it was finished, so added domes, the chimney, running boards and pipes in between operations on the frame. It kept things interesting, but did mean I got ahead of myself at times.

These next photos show progress on the boiler, and hide the fact that I couldn't figure how the eccentric cranks should be fitted. I wasn't happy with the splash guards over the drivers, either. I did what any sensible person would do, and pretended they weren't there.

The Fun Stuff
With the basic frame finished, I could start adding details to the boiler. I had a bit of trouble knowing when to stop.

Forgetting Bits
One side-effect of ignoring bits that scare you off, is having to address them later when it's a lot harder to do.
With the boiler almost finished, and the cylinders and valve gear working well (apart from the eccentric cranks), I had to start doing the bits I'd not been able to figure out and had "left to do a bit later on". That meant adding the drawbar, splash guards, brakes and other such details at a point where I risked de-soldering much of my work. Not to mention making it harder to solder them on square and true. I managed it with a lot of messing about, and lumps of soggy loo paper...

Here, I'm adding a new tender drawbar. The whitemetal one in the kit seemed too thick. Ironically, now that it's finished, it's almost hidden anyway...
I learned that the eccentric cranks were designed to be soldered to the con rod screw and therefore had to screw in exactly the same amount every time, to stay in alignment. I didn't like that idea, so I fixed threaded pins to the drivers instead. The eccentrics are soldered to threaded tube, which precisely screws onto the pins.

The final piece of piping to add was the lighting conduit. I used NZ Finescale junction boxes. The ends had to be drilled out 0.4mm, which made me sweat. The wire seated in the hole a lot better, once I filed a very slight taper to it. I also made a coiled flexible conduit up to the cab.

In a last-ditch fit of madness, I also made the brake levers and clevis links under the cab. I'm glad I did, as they just seem to finish the picture.

Beyond Me
I've now learned enough about scratch-building in brass, to know when to say, "enough" and use available technology. This one-piece printed backhead would have taken weeks to make in brass, and not been anywhere near as good.
Six months on, and this has become the most satisfying model I've built. It runs very smoothly on DC power and only awaits a decoder, lighting, and a paint job. Taking the time to add those extra layers of detail have paid off both in modelling enjoyment, and as a final result.
It only occurred to me after I'd finished, that since I scratch-built the frame and a lot of the details too, I've learned enough to do something I've always wanted: make a locomotive in brass, by hand.

Thanks heaps to Peter for his encouragement and a stack of great photos, and to Lawrence at NZ Finescale for good advice, a set of roller bearings, and one of his fantastic one-piece backheads.

And to my Dad, who gave me pretty much everything.
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