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 the late David L O Smith. Full details of this conversion can be found in below.
Reworking an Ixion Hudswell Clarke

Figure 2. Just Like The Real Thing Derby 2s described and built by Tony Geary
Kit Built Derby Type 2

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 Whitby Tank.

Figure 4. Prototype Brush ‘Falcon’ scratch-built in plastic card and brass by Steve Hoather. Full details of this build can be found in the Brush Falcon
===== Purpose of this article ===== This article is intended to help in finding useful and informative resources. Currently, there are kits available for most types of locomotive class, particularly steam prototypes, and the range is continuously expanding. 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, although resin castings for complex parts such as boilers or casings are becoming common. Kits do vary considerably in quality and complexity. Before making any purchase, here are some points to consider: - The choice of wheel standard, Coarsescale, Finescale, or ScaleSeven is fundamental. Most kits are designed for Finescale but can fairly easily be adapted for ScaleSeven, but can be quite difficult to adapt to Coarsescale. In Coarsescale the reduced wheel back to back dimension usually requires that the frames be narrower. If there is doubt that a kit will accept a certain wheel standard, the manufacturer should be contacted for advice. There is more information on this in Standards but standards should not be mixed. - Most kit manufacturers can advise on a suitable motor/gearbox unit and wheels (if not included) for their kits. - 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. ===== Choosing a kit ===== 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 by asking modellers who have built many kits, or who have knowledge of most kits and manufacturers. Also, the kit reviews on the Guild forum are an excellent source, along with reviews and articles in past Gazettes. Many forum posts and Gazette articles are now available on the GOGWiki. If you have a particular kit, prototype or manufacturer in mind first try searching the wiki. ===== Required skills and tools ===== 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. ===== Scratch-building ===== 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. ===== ‘How to’ resources ===== The original Guild Modellers' Manual contained an extensive sections on model locomotive design and construction, which have been adapted and extended for the GOGWiki. This information is not limited to scratch building. The articles on motor and gearbox selection and current collection (pick-ups) are relevant to kit building, and other articles will assist in answering that eternal question “what will it pull?”. == Chassis design and construction == * Introduction to chassis design * Steam locomotive chassis * Diesel and electric locomotive chassis * Locomotive compensation systems == Motor and gearbox selection == * motor_gear_guide == Current collection == * Current collection ==== Other sources ==== * The Guild Forum ‘Modelling’ sections are where 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 contains inspirational and informative material. * Other online forums for modellers, such as Western Thunder and RMWeb, also contain much useful information on loco construction. * 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. * 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 Product Directory is an invaluable resource for materials, parts, etc. as it lists many thousands of components available for scratch-building or improving/detailing kits. * The Guild Trader search contains a searchable list of traders who offer material, castings and machined components. * 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.