Model Engine Works: 00n3 0-4-0 Neilson Style Tank Engine

With the arrival of the Hornby Branch Line trainset in TT120, which features the little D4 Normandy tank engine, we finally have a decent little donor chassis for 00n3.

Although it's one of the more basic types that Hornby has designed for the TT120 range, it does offer outside cylinders, though no valve gear. It has a cordless motor with a flywheel and is 6-pin DCC ready if you wish to go down that rabbit hole. If you operate it with a decent DC controller, you can get a good performance from it.

I have been helping to develop and print quite a few 00n3 loco bodies and rolling stock over a number of years now, and have ended up with a few samples but nothing to run them on. With the train set being offered for less than the price of most ready-to-run 009 locos, it seemed a good idea. I would have a test track plus a couple of wagons and a ready-to-run chassis to use, with a little conversion.

I decided to revisit an old design that I worked on about 2020 and had printed on Shapeways. This was based on a standard gauge engine by Neilson of Glasgow: a 0-4-0 with an unusual piano tank and cow catchers. The original also had side plates; but for this version I decided to reduce this to crosshead covers only to make the connecting rods visible at the rear.

The Hornby mechanism is very compact: the clips designed to hold the chassis to the diecast body made it ideal to clip onto the revised foot plate design I came up with. The cylinders were a bit small, being 3mm scale, so I designed larger ones that included the covers for the cross heads. This is very similar to the old Hornby and Dapole Pug.

The bodywork was a shortened version of the original 009 tram engine model. I split the model to suit the Bamboo Labs ‘A1 Mini’ FDM filament printer that I use, so layer lines did not show as much. It took only three prototype prints to iron out all the glitches and fit the footplate to the chassis. The bodywork only needed one prototype before I was happy with the results.

After assembly of the models' various pieces into three sections – the footplate, body and rear cab – I added the handrails, regulator, and Greenwich couplings. Once these were fitted, I could look at getting the paintwork done.

The painting finish is a layered process that I find works well for me on my FDM - PLA plastic prints. Firstly, I apply a build-up of acrylic spray primer, in white or grey: this highlights any layering that needs to be softened or filled, before alternating applications of spray primer and clear acrylic lacquer are applied to smooth the surface. This gives a more controlled and level finish.

The final coloured finishes are Vallejo acrylics, applied by brush, with a few drops of acrylic thinners added to help the paint to flow. For any metallic paint, I have gone with Green Stuff as they are more vibrant and metallic-looking. The cream lining and lettering are from Fox Transfers. A topcoat of Humbrol oil-based matt varnish is used to seal the paint and decals.

I decided to go for a different coloured livery to my usual favourites. As this was based on a Scottish engine, the Caledonian blue with cream lining seemed appropriate - and it goes well with a couple of coaches which are based on the original R&ER stock but finished in a red and cream livery.

The crew is a couple of white metal figures from Dart Castings. I like the weight that they add. I know most people now go for the Modelu 3D printed figures, which are fantastic and highly detailed; but at this scale I cannot see the details, especially in a tiny cab that this engine has - a face is just a pink dot. Some more finishing touches, such as real coal added to the bunkers, lamps, and brake pipes, all help to give the engine its own character.

Tuesday, 11 August 2026

00n3 0-4-0 Neilson Style Tank Engine

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