What is NZ87, HOnz or HOn3.5?

Scene from Lewis Holden's HOn3.5 / NZ87 layout

Like most readers, I got started in this hobby with an OO scale Hornby train set for Christmas. My uncle, a former driver for Tranz Metro and long-time model train enthusiast and my grandfather built a loop of Hornby set track, and I was, no pun intended, hooked.

Fast forward to homeownership and all its many joys, I finally had my own space in a single-car garage that was too small to fit a single car in. I started building a 1:64 scale layout but found that there wasn't enough space to run the sorts of modern-era trains I wanted. I made the decision to focus on the era I knew best, the late 1980s to the mid-1990s, when I grew up in Pukerua Bay north of Porirua. That means longer trains of bogie wagons and limited four-wheel wagons.

Following a house move, I switched to NZ120 and built a number of wagons, a DSG class locomotive and a DC class locomotive, both acquired via Shapeways. At the time I became interested in the possibilities 3D printing offered and started creating my own designs. Following yet another house move in 2017 I once again had my own space for a layout and while I was still working in NZ120 started to have a look at 1:64 again. I figured I had the same problem as before: not enough space to run long trains.

Around this time I saw what a number of modelers were doing in Queensland with HOn3.5 scale. HO scale is 1:87 (technically 1.87.1, but who's checking?) and the most popular scale in the world. HOn3.5 is 1:87 scale, but uses 12mm gauge track. Almost all of Queensland (and New Zealand) has 1067mm gauge track; this works out at 12.25mm at 1:87.1 scale; so a quarter of a millimetre out from the HOm (m for metre gauge) 12mm gauge track used by the metric system. Because of my previous dabbling in NZ120, I've called it NZ87 to distinguish from people modelling NZR in HO (or OO) scale with the usual 16.5mm gauge track.

There have been a few cheerleaders for HOn3.5 scale NZR over the years, including the late Graham Butler, and today there's a handful of us making models in the scale. The big advantage is that there's a lot available, from the US and Europe. This is a good problem to have if it wasn't for two things: first, the extremely irritating tendency of some manufacturers, especially in the UK, labelling things "OO/HO". A number of times I've bought things (for example, tunnel portals) labelled as being HO scale, only to find on arrival that they are in fact 1:76 scale or OO. Second, because HO is the most common scale globally, there's a lot of toy-quality stuff that has only a casual relationship with the scale.

Still, as a result, it does make NZ87 a much simpler prospect in many ways, especially for those of us that are, shall we say time-poor. I've made up a number of HO scale kit buildings of modern prototypes, such as a workshops kit. Thanks to the growth in the Queensland market, there's a number of 12mm gauge mechanisms in the market; local supplier North Yard supplied my first NZ87 mechanism for a DC (later in a Back to the Future move requisitioned for a DA class model). Australian supplier Wuiske Models, probably the biggest supplier of HOn3.5 models and parts in Queensland, provides wheelsets. Their ready to run catalogue of locomotives is impressive; I acquired a 2400 class last year, most likely for eventual conversion to an EMD DF class. Wuiske Models have also recently begun making their own 12mm gauge flex-track to correct Queensland Rail specifications, which are fortunately similar in terms of sleeper spacing to NZR.

Another manufacturer, SDS Models, has recently announced a range of 12mm gauge models, including the Queensland 1620 class, which is almost exactly the same as NZRs DI class locomotives. They're due to be released in 2022.

Then there's the TT scale angle. Standard gauge scales to 12mm at 1:120 scale. So there are a lot of potentially useful mechanisms for steam locomotives in the scale. Unfortunately, TT scale models suffer from the same spectrum of toy-like to scale models as HO scale does; for some reason, despite the best of German engineering in a lot of TT scale models, they make the wheel flanges really really big; they end up looking more like a circular Pizza-cutter than a scale wheel. There are also HOm scale mechanisms in Europe and the mysterious HOj from Japan. Both are fairly expensive from what I've been able to find, and for some reason, the Japanese use a scale of 1:80 for HOj, which would make 1067mm gauge closer to 13.3mm, rather than the 12mm gauge they use.

For wagons and locomotives, I've applied 3D printing to the task. I recently acquired an AnyCubic Photon resin printer, and have printed out a number of wagons (PK and UK class container wagons, L and LA class highsider wagons) already. What this all adds up to is a whole heap of technical challenges, which to me is where the fun of this hobby is. I've got a mostly operable layout with PECO HOm gauge track and turnouts and more recently a DCC++ EX controller (more on that later!).

NZ87 is well suited to 3D Printing as there's not much available in terms of kits or parts. I've paid a professional designer to create a "DA" class design in a few of the classes variations, which I've released publicly on Thingiverse for anyone to download and use. My other wagon designs, containers etc are all available on the website as well, and a few others have contributed their designs. We're starting to build a community of modellers, which is the goal for anyone.

If you're interested in NZ87, you can follow my progress on Facebook at https://www.facebook.com/HOscaleNZ