Model Engine Works: Skylark engine

Sunday, 7 February 2021

0-16.5 Engines

Updated 2022

It was at the Halifax 2019 model railway show that I was tempted by an old Hornby “Smoky Joe” style 0-4-0 engine sitting in one of the second-hand boxes. I had seen some ideas on YouTube about add simple cylinders and coupling rods to these which looked convincing when completed. Little did I think it would lead me into an interest in a new scale of 7mm.

It was some weeks later when I came round to see what I could do with the old Hornby chassis, my first thoughts were the type of engine I could build from the existing bodywork. I found a very good source of inspiration at the Smallbrook Studios web site. They do resin body conversions for the 00 chassis in a 7mm scale, there is also a good catalog of rolling stock and detailed parts.

I found one saddle tank conversion from a Hornby “Thomas The Tank Engine” Bill Loco just what I liked. I look on eBay and was lucky enough to find a body for the Bachmman version of the Bill engine. My plan was to scratch build a new cab and smokebox door, then buy a cast resin dome and water tank lid. Other details I could get from various other sources.

My next thoughts were on the cylinder conversion, I looked up the You Tube video I had seen previously. The parts used on that were spares form a Hornby Class 28XX 2-8-0 Loco Valve gear, I got a set of these from Peters Spares. Only the crossheads and slide bars would be needed for this job so the other bits would be saved for something in the future. To attach the crossheads and the coupling rods I required some very small 14BA machine screws nuts and washers, and eBay came up with a suitable supplier of these.

I would need to build some simple cylinders to fit onto the existing chassis, and remove the existing moulded ones. To do this I laminated together a couple of Placticard blocks and a bridge between them to form a cylinder arrangement. Holes were drilled to give a clearance fit to the crossheads and a tight fit for the slid bars. The chassis was cut to allow the cylinders to sit in the correct place.

The next job was to alter the coupling rods, these needed to be cut in front of the dummy cross heads, and a clearance hole made in the centre of the rod for the 14BA screws. Once done the screws can be passed through from the back of the coupling rods, a washer placed between them and the crosshead, then a couple of nuts used on the outside of the crossheads will lock them in place. It all needs to be a loose fit to work. Once all is fitted together a quick test run will let you know if any adjustments are required for smooth running.

Once the chassis was running, I started thinking, could I 3D print a version of the cylinders and crossheads. So off I went to the computer and came up with a version that used 0.7mm brass wire for the slide rods and cylinder rod. I used White Versatile Plastic to create the prototype print and after a couple of attempts, I got them working. So I added these to the loco I was building.

There came a point when I had to add the Bachmman body to the Hornby chassis, This was not a straight forward fit, but with a little cutting and a bit of Milliput Putty, it went together. By removing some plastic from the bottom of the footplate around the front and rear couplings and infilling a small section to the front of the footplate, where an 8 BA nut could be bonded to the underside. The chassis in turn needed a slot cutting at the back to allow it to fit the rear bodywork. A hole was drilled through the front of the chassis in the centre of the cylinder bridge to allow an 8 BA screw to pass through, this is to hold the chassis and body together. NEM Coupling pockets were fitted in place encased in Milliput putty at both ends of the chassis,

Once I had completed the scratch-built body the natural progression was to see if I could produce a 3D printed version of a body. The only thing to decide what engine to have a go with. In the end, I worked on two types the Skylark style and Peckett style engines which I had already done in 009. These were scaled up and reworked around the new chassis. The idea being, to create a body shell with the cylinders already attached. These could be used as simple conversion to the Hornby chassis by removing the cylinders and couplings from the Hornby chassis, then the chassis would simply push into place under the new body.

If you wanted to go further you removed the cylinders from the printed body also and add the additional printed cylinder block and crossheads to the chassis to create a more detailed version of the engine. They would also have pockets in the buffer beams to accommodate NEM coupling pockets at the correct height. Well, it all seemed like a good idea.

I had two prototype prints done in White Versatile Plastic to try these out, they both fitted the chassis as expected and work well as simple conversions.

I have also done a third body now, this one is a quarry Hunslet style with a cap that can be built in three versions, one open, one with no back, and a fully enclosed version. I just could not make my mind up which I liked best.

I Have now added a Sharp Stewart Tattoo Saddel tank to the ranks of the 0 gauge fleet of small engines. It is printed with some alternative parts such as funnels. This one is designed to run on the 0-6-0 Electrotren chassis with the rear wheels swaped for a 10mm solid disk type to form a pony wheel.

I have added a list of additional fitting that I used and the supplier below. The three printed bodies and cylinders conversion are available on Shapeways at:

https://www.shapeways.com/shops/model-engine-works?section=0-

16.5+Engines&s=0

List of Parts:

Hornby 0-4-0 Chassis or Electrotren 0-6-0 Chassis

Printed or scratch-built chassis blocks

Brass 0.7mm brass wires

Parts from Peters Spares

Hornby X8834W Class 28XX 2-8-0 Loco Valve Gear Set Weathered.

Couplings and NEM pockets

sales@petersspares.com

8BA Screws nuts and washers

14 BA screws nuts and washers

Sunday, 10 March 2019

009 Skylark Style Engine

3D print of this engine is now available at Model Engine Works on Shapeways.

https://www.shapeways.com/shops/model-engine-works

One small engine which a lot of people seem to have on their layouts is the Kerr Stuart 0-4-2 Skylark. Most use the white metal kit and a chassis such as the Ndrive 0-4-0 with a pony wheel added. I was impressed by the one built by Michael Campbell using the Kato chassis with side plates which mimicked the pony wheel with the rear wheel of the Kato chassis, a simple but really good solution. http://michaelsrailways.blogspot.co.uk/2012/10/a-little-bit-of-skirt.html

I decided to have a go at scratch building my own version of the Skylark. As I was looking to build something in this style rather than recreating the actual engine, there were possibilities to make a few changes to the model and still keep the look and spirit of that style of engine.

I got as many reference pictures as I could find together and also one of the Kato 11-104 chassis.

These are very good when getting into modelling 009 narrow gauge engines as they are so reliable and inexpensive. These can be used on engines that are made with side plates, which were usual on roadside tramways built in the UK and Ireland.

I started by making a mock-up footplate, to get the right-sized opening to fit the chassis. Once I had that sorted I made a few scale drawings of the bodywork, using the pictures as guidance.

My plan was to build the engine from different thickness of sheet Plasticard and spare pieces from old model kits that had been left over.

To make the body I printed some paper patterns from the drawings that I had made, which were temporally fixed to various thickness of Plasticard with Pritt stick. This holds them long enough to cut out and the paper then just peels off afterwards.

The smoke box having a round top was formed using 1mm front and back shaped pieces fixed to the rectangular base. Then thin sheet Plasticard was formed over this in two layers. This is easy to bend to shape and by gluing the additional layer strengthens it up. The same idea was used on the boiler, with an additional layer being used to create the bands around the boiler. Of course if you have the right size tube this will save going to the trouble of making the boiler.

The chimney and dome were made using lime wood and turned in the chuck of a small electric drill.

If I had known about the “Gem 9104” white metal OO-9/ industrial loco fittings beforehand I would have used one of these chimneys and the dome.

http://www.lytchettmanor.co.uk/lytchett-manor/oo-9-couplings-fittings

The smoke box door was made up of two discs of 1 mm Plasticard sanded to shape, the hinges and handles were added using spare bits from an Airfix 040 saddle tank kit.I formed the spectacle windows by drilling an oversized hole and lining this with strips of thin Plasticard sheet to give the impression of a brass frame when painted. I made use of a pair of vacuum pipes from a spare Vale of Rheidol coach.

The upper edges to the water tanks have a strip of the Plasticard added round the top and this is then filed to a D shape with the top inner edge softened, which forms a slight well at the top of the two side tanks.

I used one of the Dapol track side figures for the crew. I did find that I had to shorten the legs on this figure as in general they are slightly over size in some of the smaller engines.

I made the lamps in bulk some time ago using white 1 mm thick plasticard rectangles to form a 3 x 2 x 2mm block and then added a 2mm disk on top, and for the lenses I used a small 2mm clear or red rhinestone.

The paint was a mixture of various Humbrol colours to produce a shade of maroon that I liked. A final coat of matt was added to the footplate and smoke box, then satin varnish over the maroon painted areas. I used real crushed coal in the bunker – you need to get this almost like dust at this scale to look right.

The finishing touch was a set of name and works plates from Narrow Planet who do the brass etched plates to order. “Fergus” was my chosen name with a separate set of works plates.

https://shop.narrowplanet.co.uk/

It has been a good practice run for me and I have enjoyed the challenge of the build.

This popular little engine is now available as a 3D print to run on the readily available Kato 11-104 chassis. It has separate foot plate body and roof to allow for interior details to be added, there are also a pair of simple couplings printed under the foot plate of the model.

Additional details will be needed to complete the model as show, these include smoke box door handles, cab side handrails and working lamps.

If you would like a 3D print of this model visit Shapeways at:

https://www.shapeways.com/product/733QP7JX6/009-skylark-style-engine?optionId=117106865