Locomotive Construction

Today, there is a plethora of ready-to-run locomotives to suit all pockets and tastes, however there are by no means as many prototypes covered as in other scales. Many 7 mm scale modellers will at some time therefore indulge themselves in the delights of constructing their own locomotives, either by modifying ready-to-run, building kits, or scratch-building.

The most common method of model locomotive construction is by modifying or improving ready-to-run models, or by kit building. Typically, with kits, modellers start by building a simple commercially available kit, then they move on to either more complicated kits, or to scratch-building. The photographs show a sample of models and give details of where more constructional information on these specific models can be found.

With this in mind, we will offer an overview into kit building first, followed by an overview of scratch-building. Improving ready to run models can encompass both kit and scratch-building.

Figure 1. A ready-to-run Hudswell Clarke model, by Ixion Model Railways, modified by David L O Smith. Full details of this conversion can be found in Gazette Volume 19-5-page 30 (Home>Publications>Gazette Archive) , or further details are also available on David’s website: www.davidlosmith.co.uk/GCR_Humber.htm

Figure 2. Kit built ex L.M.S. 2-6-0 ‘Big Ivatt’ built by Tony Geary from a Modern Outline Kit (MOK). A detailed description of the construction can be found in Model Railway Journal, issue 238

Figure 3. North Eastern Railway ‘Whitby Tank’ scratch-built in nickel silver and brass by Nick Dunhill. Full details of this build can be found on the Guild Forum in the ‘My Workbench’ area (Home>Forum>My workbench).

Figure 4. Prototype Brush ‘Falcon’ scratch-built in plastic card and brass by Steve Hoather. Full details of this build can be found in Gazette volume 19-10-page69. (Home>Publications>Gazette Archive)

Rather than providing a detailed breakdown of how to build a locomotive, this short document is intended to give you a helping hand with finding useful and informative resources (see below).

Currently, there are kits available for most types of locomotive class, particularly steam prototypes, and the range is continuously expanding - see the adverts in recent copies of the Gazette, or the Traders section of the Guild website. Most kits typically provide a combination of photo-etched (pre-cut) brass or nickel silver etches or ‘frets’, brass and/or whitemetal castings and machined parts; kits do vary considerably in quality and complexity. Before making any purchase, here are some basic points to consider :-

1. Coarsescale, Finescale, or ScaleSeven wheel standard - this is fundamental, as most kits are designed for Finescale but can fairly easily be adapted for ScaleSeven, but can be quite difficult to adapt to Coarsescale, due mainly to the reduced wheel ‘back to back’ dimension (28.0mm, see the Standards section of this manual or here) which usually requires that the frames be narrower; if there is doubt about a kit, the manufacturer should be contacted for advice. There is more information on this in the Standards section of the Revised Manual but standards should not be mixed.
2. Most kit manufacturers will advise on a suitable motor/gearbox unit and wheels (if not included) for their kits.
3. The tightest curvature of trackwork the model is to run on defines the amount of sideplay in the axles that is required, and the compromises that must be made to accommodate the movement of bogies and pony trucks.

We would recommend that members new to kit building always choose a simple prototype to begin with, then move on as skills develop. Some manufacturers produce specifically designed starter kits and they are happy to discuss their products with prospective customers. Information about suitable starter kits can also be found at a local modelling group (Home>Clubs) by asking modellers who have built many kits, or who have knowledge of most kits and manufacturers. Also, the Guild’s Forum (Home>Forum>Kit Reviews) is an excellent source, along with reviews and articles in past Gazettes (Home>Publications>Gazette>Archive)

We strongly advise you to consider joining your local group where there will be a wealth of knowledge and experience (and friendship) available and fellow modellers are generally happy to offer help and advice, and to share their experiences. Reading through kit reviews in the Gazette or on the Forum may help you choose a suitable project.

A few basic workshop skills are required to build starter kits but, as kits become more complicated, the same skills are needed but experience and confidence play a large part. These skills include the ability to solder, drill holes, fettle castings, shape etchings, ream bearings, etc. Kits do have many inbuilt aids for builders, such as location slots and tabs, and parts which are pre-cut out ready for assembly, and many kits have the larger components pre-formed as well.

You will need a number of basic tools to get started: a set of needle files, jeweller’s screwdrivers (even the ones from a Christmas cracker will get you going,) tweezers, pliers and cutters, a good scalpel, a piercing saw, a soldering iron and a mini drill, a small vice and a work surface. A good scale drawing and photos of your prototype are also very useful. Of course, as your experience and skills expand you will inevitably acquire many more useful tools to help you on your journey.

The Original Manual offers guidance that is still relevant today and in the Guild Forum ‘Modelling’ sections (Home>Forum) GOG members describe and demonstrate the basic kit construction skills that work for them. Various threads cover workshop skills and they will continue to expand as new posts appear. The Guild video collection (Home>Services>Video Library) also contains inspirational and informative material. Other online forums for modellers, such as Western Thunder and RMWeb, whilst not specifically for 7 mm scale modellers, do contain much useful information on loco construction.

Rapid responses to questions is a characteristic of social media, such as YouTube and Facebook (other platforms are available). Searches on YouTube (it may be productive to search also ‘Model Railroading’) will yield numerous video clips posted by modellers from all over the world explaining how to solder and how to drill and form thin material, for example. Facebook has many O gauge groups that will put you in touch with hundreds of fellow modellers who have posted content showing their experience of building many types of locomotive and who will be able to offer help with any problems you may encounter.

For those who prefer an ‘old school’ approach, many books are available that provide similar guidance; these are available from specialist book websites, libraries and book stands at model railway shows. The ‘Wild Swan’ publications are excellent and the ‘Hints and Tips’ booklet by Connoisseur Models is highly recommended.

The Guild website Product Directory (Home>Products>Products Directory) is an invaluable resource for materials, parts, etc. as it lists many thousands of components available for scratch-building or improving/detailing kits. Joining an O gauge group with experienced modellers may present many ways to solve problems and they should be able to help you decide which is best for you and your model.

Scratch-building may sound rather daunting, but it is really only one step beyond building from a kit; the main differences are that you will need to source all the bits for a model rather than buying a kit of parts, and you will need to acquire accurate scale drawings. Sheet (typically card, plastic, brass and nickel silver) needs to be cut out to suit the individual components required to assemble the model. Most of the skills and the tools required will have been acquired through experience of building kits.

In addition to the resources listed for kit building, the Traders section of the Guild website (Home>Traders) contains a searchable list of traders who offer material, castings and machined components that are particularly valuable for scratch-builders.

Perhaps the hardest part is actually making a start but, the important advice is to enjoy the experience, to pick something simple to begin with, do your research, and to seek advice from fellow modellers if you become stuck. Happy modelling!