Getting Started in 3mm: FAQ

A guide to getting started with your first 3mm/ft project

Nigel Brown
(photographs by the above unless otherwise stated)

1        Where do I start?
2        What track gauge and standards are used?
3        Which track gauge and standards should I choose?
4        What track is available?
5        How would I construct track?
6        What wheels are used?
7        What couplings are used?
8        What motors and gearboxes can be used?
9        Will I need to use compensation or springing
10      What pickups can be used?
11      Can I use modern control systems such as feedback controllers or DCC?
12      What would be a good wagon to start with?
13      What would be a good locomotive to start with?
14      What would be a good coach to start with?
15      What transfers and name or number plates are available?
16      What further information and services are available?
17      What next?

1            Where do I start?
The railway modelling scale of 3mm/ft started life as Triang TT, and indeed even today there are many Triang TT collectors. However, at an early stage the scale attracted enthusiasts interested in building their own models and developing interesting attractive layouts. Initially they were supported by companies such as Bec and GEM.  Then the 3mm Society was formed, and rapidly became the mainstay of the scale. Over the years the Society has introduced many kits, components and tools, and most of all has provided a forum where experience can be shared, needs discussed and addressed, and ideas floated. The Society has put a lot of effort into ensuring that products have kept pace with developments in the hobby as a whole. For example there is now a comprehensive range of quality wheels to cater for modellers needs, components to assemble your own track, while the range of highly detailed plastic wagon kits from suppliers such as Parkside and Cambrian stand comparison with those in any scale.

So, where should you start? We suggest that one good way would be to try a couple of wagon kits which interest you, knock up a couple of feet of test track to run them on, and then think about having a go at a locomotive.  However, before you can actually build anything you need to make a few decisions about what track gauge, and related standards, you are going to use.  Read on.

2             What track gauge and standards are used?
Triang adopted the international TT standard gauge of 12mm but a scale of 3mm/ft (1:101.6) rather than the smaller TT scale of 1:120; this was accomodate the rather cramped clearances of British prototypes. Although 12mm gauge is undersized for 3mm/ft , it is widely used, for finescale layouts as well as those based on Triang.  The Society publishes three alternative standards to be used with 12 mm gauge, based on the type of wheels to be used. The standards are Coarse (Triang), Intermediate (originally based on wheels such as Sharman and Maygib), and Fine (compatible with the Society's own finescale wheels). In practice, most modellers choosing 12mm gauge use Intermediate standards, and now benefit from a new, comprehensive range of Intermediate standard wheels introduced by the Society; these are known as SQ wheels since the steam locomotive driving wheels fit on square-ended axles, similar to the Romford wheels of old, to aid quartering.

An alternative to 12mm gauge is the prototypically correct 14.2mm gauge, using Society Fine standards. This has long been used by a number of Society members, aided by the very wide selection of Finescale wheels produced by the Society. A recently developed service has been the conversion of round-holed locomotive driving wheels to square-holed, similar to the SQ wheels, to provide the same advantages of automatic quartering.

 A gauge of 13.5mm has also been around for a long time, a sort of 3mm equivalent of the 4mm EM, and has a currently small number of users. It has advantages for certain prototypes where the clearances in 14.2mm gauge are a bit tight. Both Intermediate and Fine standards are available, and the corresponding wheels..

The gauges discussed above are, of course, related to the "standard" prototype gauge of 4' 8.5". However a number of other prototype gauges are also  modelled.  Thus 9mm is used to represent 3' gauge, 15.75mm to represent Irish 5' 3" gauge, 16.5mm to represent 5' 6" gauge, and 21mm to represent Brunel's 7' gauge.

3            Which track gauge and standards should I choose?
12mm gauge is widely used, and there are many fine layouts which use it. It is the one gauge for which commercial track is readily available, from both Peco (HOm) and Tillig (TT) , although the range is limited, and indeed many modellers use hand-built 12mm track. The main question is whether you would be satisfied with the underscale appearance of 12mm or whether you would prefer a gauge closer to the prototype. A secondary question is if you adopt 12mm gauge, do you use Intermediate or Fine standards? If you build your own track you can use either, although most people use Intermediate. One disadvantage of 12mm gauge is that the wheels are closer together, which can limit the choice of gearboxes and motors in locomotives.

14.2mm is most likely to appeal to those who want to build fine scale track to prototypically correct gauge, and relish what challenges there are in doing so. The standards themselves are pragmatic; the Fine standards are not S3, they are effectively a scaled down EM pushed out to correct gauge, and are fairly easy to employ. The wide range of good-looking wheels available is an added bonus. Also, etched locomotive kits reduced from larger scales can usually be built without further work to this gauge, not always true of narrower gauges. The main challenges are with locomotives with outside cylinders, and sometimes valve gear, where the slightly thicker-than-scale wheels can lead to tight clearances; for example, one dodge is to push the cylinders out slightly.

13.5mm gauge is most likely to appeal to those who want something closer to the prototype, whilst avoiding the fine clearances in 14.2mm. To get the most advantage though, you need to use Fine rather than Intermediate wheels, with the track standards to suit.

In the remainder of this guide you may find further things to help you with your choice; a more detailed look at the track issues in particular is recommended.  One thing which could be worthwhile would be to try a wagon kit with both 12mm and 14.2mm wheels (easily swapped if you position the brake gear carefully), and see what you think of the difference. A recommended choice would be one of the Society's Parkside wagon kits, with the Society's own Intermediate and Fine wheels.

4            What track is available?
The principal off-the-shelf ranges are produced by Tillig and Peco. Tillig produces a range of 12mm track for international TT (1:120, approx. 2.5mm/ft), with points in both ready to use and kit form. The track is good quality, although in appearance it's fairly obvious that it's intended for a smaller scale. Peco 12mm HOm track is nearer to scale appearance, and the right and left hand 24" radius points are usable with Society Intermediate wheels, and sometimes Triang (with adjustment); however, care is required with other Peco pointwork such as the curved point, which has a very sharp 15" inner radius.

 The Society produces a range of track components including rail and track bases which covers all gauges. Those who favour soldered track construction can use PCB timbers and sleepers, and either Code 80 flat-bottomed rail, or finer Code 60 bullhead rail. However, plastic track components provide a popular alternative. For plain 12mm Intermediate track you can use Code 80 rail and Society Ratio track bases. For plain Fine track in 13.5mm or 14.2mm gauges you can use Code 60 rail and Society finescale track bases. Thus it is very easy to produce plain track for any of the main three gauges; in principal it's no different to using commercial flexi-track.

Society also supplies plastic chairs for Code 60 rail, mainly for constructing  finescale pointwork in any gauge. The chairs are designed to be glued to either ply timbers and sleepers (provided by the Society), or plastic ones cut from Plastruct or Evergreen strip. You could also use these chairs to construct plain Fine track in 12mm gauge, or indeed other gauges such as Irish 15.75mm gauge, for which bases don't yet exist. You could even use them to construct track to Intermediate standards in 12mm scale (of finer appearance than the Code 80 rail and Ratio bases), but only if you use the Society's modern Intermediate standard wheels; older Intermediate wheels have flanges which are too deep.
What if you like the idea of using Society components for plain track, but are worried about constructing matching pointwork? 3SMR offer a service constructing pointwork to order, in the principal gauges.

5            How would I construct track?
As indicated in the previous section, for most purposes plain track can be easily constructed using the Society's plastic components, although you may prefer soldered construction, and if your prototype track is flat-bottomed, not chaired bullhead, this may be the best way.

Pointwork requires more work, but is easier than perhaps imagined, and well worth giving a go. The main effort is constructing the V part of the crossing (sometimes called the frog), which requires rails to be filed to the right angle then soldered together. The switch blades also need some filing. Other than that, it's mainly a question of proceeding logically (many people start at the frog and work out from that), adding rail until the point is complete. The process is similar whether you use soldered construction or use  the Society's chairs. Points have a number of specialised chairs and these can be produced by butchering the Society ones.

Accurate track gauges are the key to producing good working track.  Finney & Smith produce a good range in all gauges, while 3SMR produces roller gauges in 12mm and 14.2mm.  The Society provides a high quality jig for machining and forming point V's, for code 60 rail only.

Templates are a very useful guide when constructing track, although the accurate bits of the operation are done using the gauges. The Society provides sets of point templates in 12mm and 14.2mm, although you can also use ones reduced from larger scales.  However, an increasing number of members produce their own templates using Templot software.  Templot produces prototypically accurate plans in any scale, including 3mm/ft, will cater for all Society standards, and can produce complex formations, or even complete layouts, as well as individual points.

If you've never done it, track production may seem daunting, but it isn't, so give it a go.  All you need is a small amount of the basic components, and a gauge or two for your chosen track gauge.

6            What wheels are used?
Although in the past a variety of wheels from different sources have been available, most have disappeared. We recommend that you stick to the Society's own wheels where possible. The Intermediate  wheels are to the internationally recognised NMRA RP25 Code 79 standard. The Fine wheels are to the Society's own Fine standards.

The current range of Intermediate wheels is aimed at proving a basic offering in all the main sizes likely to be required. The Fine range, which has evolved over a much longer period, not only covers such sizes and more, but offers prototypically accurate alternatives, such as a different number of spokes for different prototypes.

In the past, Romford wheels proved popular due to the square axle end which greatly simplified the process of quartering driving wheels.. For this reason square axle ends have been incorporated in the design of the Society's Intermediate wheels. The Society's Fine wheel currently still need round axle ends, but if you want simpler quartering one member provides a service converting them to square ends, for a modest fee.

You'll usually need appropriate brass bearings for your wheels.  Slaters (Society SL4) pin point bearings are the most useful for wagons, Kean Maygib KM6 for coach bogies, KM22 inside bearings for inside use on 1.5mm axles, and Branchlines 1/8" short top hat (straw hat) for steam driving wheels; all except the Branchlines bearings are available from the Society.

7            What couplings are used?
B&B 3mm couplings are popular; they are unobtrusive, self-coloured, assembled just by bending (with care!) and feature remote uncoupling.  Some prefer the operationally similar DG couplings for more robust use; other types include Spratt and Winkle.  The traditional Triang type of  coupling, in various forms, is still used.

8            What motors and gearboxes can be used?
Mashima open frame motors (12/16 or 12/20) have long been used.  14.2mm users can often, with advantage, use the more powerful, slower and smoother Mashima 1220 flat can motor (or sometimes even the 1224); the 1220 can be squeezed into some of the larger 12mm locomotives. The smaller Mashima 1015 and 1020 flat cans can also be used; the 1015 has a mixed reputation but the 1020 seems a good motor.

The Branchlines RSL  gearbox is an old favourite, and has the advantage of a grub screw, useful if you think you may want to pull things apart. Branchlines 2-stage gearboxes have also been used. However, the Branchlines gearboxes require careful checking, assembly and running in to work well.  High Level multi-stage gearboxes offer a quality alternative which is easy to assemble. Finney & Smith stock two High Level Slimliner gearboxes developed for 3mm scale, the 3-stage Compact and the 2-stage Compact+; the gearboxes offer a choice of 3 gear ratios.

For diesels, a variety of approaches are possible. 3SMR stocks Bullant motorboxes, amongst others, or will obtain them to special order. The Society produces some motorising kits which may be suitable.

9            Will I need to use compensation or springing?
In a few cases, such as long wheelbase 4-wheel wagons or coaches, compensation may be of benefit. Worsley Works offers a simple etched inside bearing compensating frame, which may be useful, and the Society offers etched compensating W-irons. Otherwise, for wagons, generally no.  For bogie coaches, the well known MJT bogie kits are recommended, which include a neat simple compensation arrangement, and give very smooth running. Uncompensated bogies can be obtained from 3SMR.

Locomotives generally don't need compensation. However, some form of flexible chassis arrangement may improve running and offers opportunities for improved current collection. But you don't need to go down this route unless you want to.

10            What pickups can be used?
You can use just the same methods of picking up current as you would in any other scale.  Brass or phosphor bronze wire bearing on tyre treads, or phosphor bronze strip bearing on the backs of treads, are all used.  A few members have used split frame methods.

11            Can I use modern control systems such as feedback controllers or DCC?
Feedback controllers are widely used.  Modern motors appear to give no problems, but older motors such as those in Triang locomotives may suffer from overheating.

Some modellers are trying out DCC.  Provided your locomotives have suitable motors and perform well, and in particular pick up current reliably, there appears to be no problem, but it may be good idea to get your  locomotive to work well under DC before converting it to DCC.  N scale decoders can usually be fitted, and in some cases OO/HO ones.

12            What would be a good wagon to start with?
The Parkside wagons offered by the Society (code beginnning PP in the Society lists) are high quality, go together easily, and include examples from pre-grouping to modern;  you'll need wheels, bearings and couplings of your choice, and of course paint and transfers. The Society offers some transfers while 3SMR offers 3mm versions of a number of Modelmaster transfers. For a wider choice, apart from the Society, other wagons are available mainly from Finney&Smith (including some distinctive and some older period examples) and 3SMR.

13            What would be a good locomotive to start with?
This depends very much on your taste, experience and inclinations.  For steam locomotive buffs, some very high quality etched locomotive kits are available complete with fittings, for example those derived from Malcolm Mitchell 4mm kits, but they take time and skill to complete, and even with experience you may prefer to start with something fairly simple.  The Society lists, and those of Worsley Works, 3SMR and Finney&Smith are worth browsing.  Many recent kits now employ fold up chasses which are quickly and easily assembled, and some these can be used with older kits.

The simplest bodies to assemble are the older white metal kits, such as the ex GEM  kits available from 3SMR, and some Society kits; some are crude by today's standards and may require minor modifications to use modern chasses, but they are usually dimensionally correct, can be improved by adding detail, and  may be an acceptable starting point.  Etched bodies obviously require a fair amount of soldering and take more time;  the more modern use slot-and-tab construction, which helps a lot with assembly, and if you're happy with soldering, the simpler ones, for example the smaller Connoisseur 7mm derived ones offered by Finney&Smith, or the smaller Society ones, may also be a good starting point. A few etched kits use resin castings for major body components such as  firebox/boiler/smokebox, so you are saved from forming the trickier shapes; these include the well-thought-of Brynkits range, which are obtainable from 3SMR.

With most kits you need to add motor, gearbox, wheels, couplings, paint and transfers, pickups and handrails to complete. Cram as much weight in as you can (a good rule in this scale). Some modellers revell in applying extra details.

If you're into diesel or electric, look at the offerings of Worsley Works, Bruce Smetham, and others.  For example, you could take the Worsley Works Class 58,  add a Bruce Hoyle set of whitemetal castings (now obtainable from the Society), and power it with suitable bogies from say the ranges offered by 3SMR.  Bruce Smetham produces cast resin bodies for a number of first generation diesels, including a Western, and a Class 20.  Worsley Works also does an extensive range of etched multiple unit kits.

14            What would be a good coach to start with?
The only readily built plastic coach kit available in recent times is the Society's GWR B set, which is perhaps not up to the latest standards, but will produce a decent pair of coaches; officially discontinued, examples may still be available, possibly from the second-hand shop.  You will need castings (buffers RG4 BR23, roof vents 3xRH1), bogies, wheels, couplings and window glazing.  If you want to add internal detail, use plasticard for partitions, and PP12 seats. Bogies for most coaches are produced using MJT etched frames, which are available from the Society in various wheelbases, together with cosmetic whitemetal sideframes (GWR 9' Standard ones from 3SMR for the B set).

 You can apply etched sides and ends from the Worsley Works range to an existing, suitably modified, coach;  old Triang coaches can be used, although for GWR 57' coaches the Society's B set, with sides replaced by PP20 clear plastic coach sides, is a better bet.

All other coaches are basically etched, and require varying amounts of additional components.  Finney&Smith and 3SMR coaches include castings unless stated, but may require wire and other bits and pieces. Worsley Works coaches, which are built on the Comet principle, generally include etched sides, ends and floor, but always require castings, as do the the Mallard/Blacksmith coach etchings offered by the Society.  The Society has a booklet by Tony Seal which contains a lot of useful advice on building etched coaches, and Worsley Works has one describing the Comet approach.

15            What transfers and name or number plates are available?
The BR modeller is well catered for, with various transfers from the Society, and Modelmaster transfers from 3SMR. For the pre-Nationalisation scene, the Society offers PC methfix transfers covering mainly the Big Four post-Grouping companies, 3SMR offers the four Modelmaster sets which cover many of the common Big Four wagons, while Finney&Smith offer a number of useful specialised transfers, both for railway companies and for private owner wagons. Cambridge Custom Transfers offer transfers from their standard range in 3mm.

Some locomotive name and/or number plates are available in 3mm from Kings Cross Plates and from 3SMR.  The Society kit MF1 can be used to produce almost any standard GWR number plate.

16            What further information and services are available?
Joining the Society will give you access to a wide range of products, information, services, and other members, namely:-

a)    Price List
Periodically issued to members.  Contains full listing of most Society products, with prices.
b)    Mail Order
        The place for members to order products listed in the Price List. The Society is currently re-organising this and the other
        Society "shops" to bring operation up-to-date and to implement on-line ordering.
c)    Marshalling Yard
Source of Society and Peco track, rail, jigs, sleepering, and related items
d)    Stock Sidings
The second-hand shop.  Most Triang and and a wide range of other 3mm products pass through the shop at some time or
       other. It's a good place to look if you are seeking otherwise unobtainable products, completed kits, and so on.
e)    Illustrated Catalogue
       Very comprehensive illustrated CD-based guide to products of the Society and major suppliers, including past products.
       Ideal for sourcing that obscure component you've found you need. Currently this is being adapted to cater for on-line ordering.
f)    Mixed Traffic
The Society's highly popular quarterly magazine.  Includes articles, reviews, hints, arguments, adverts.
g)    Newsletter
       Issued with Mixed Traffic.  Latest product news from suppliers, also other news, shows, area groups.  
       The main source of keeping in touch with who's producing what.
h)    Meetings
       Apart from the AGM, which is also the main showcase for the scale, there are several other major get togethers.
       You can meet other modellers, and also spend your hard earned cash on Society and suppliers' stands.
       There are a number of area groups which host their own meetings.
i)    E-list
      A lively forum for online members to share information, advice and views.
17                What next?
Well, hopefully you have enough information to get started, although naturally a lot of things, for example scenic items, haven't been mentioned.  If you haven't already, then join the 3mm Society and get the product lists.  The major independant suppliers all now have web sites worth looking at.  Think about where you want to go, make a list of the items you are going to need and from whom, then send off your orders.  However, do remember that all the people you've contacted have other lives and other commitments, and may need a bit of  time to respond to your order.  In fact, as a general rule, order things when you know you're going to need them, not when you actually do, to avoid frustrating waits if they're not currently in stock.
Once you've joined the Society, then assuming that you have internet access we recommend that you join the Society's e-list.This is a very good place to seek help or advice, or generally keep in touch with what's going on.