MODEL WHEEL CONSTRUCTION

By John Elwood

INTRODUCTION

There are several methods of making wheels practiced by Guild members. Which ever method is selected, however, the specific parts of the wheel have to be manufactured separately: the hub through which the axle stub passes; the spokes which are invariably “dished”; the rims and finally the tyres which hold the wheel together and provide a suitably hard surface for movement over the ground.

The choice of wood is largely a matter of choice. The most important issue is grain. Wheels at 1/12th or 1/8th scale are extremely difficult to finish if the grain of the wood is coarse, or open. Good quality pine, beech, birch or close-grained hardwoods are all suitable. Providing there is sufficient thickness of the wheel blanks wheel rims can be turned in pairs. It is not essential, or wise, however, to use the traditional ash, elm and oak for small-scale models.

Although wheels can be constructed without the use of a lathe it is obviously more difficult to produce the hubs and rims without one. At its simplest a power drill held in a stand with DIY tool rests will suffice but it is clear that a more sophisticated machine is desirable. The Picador (if one is available or a similar lathe) is undoubtedly the cheapest for it is a self-assembly unit comprising precision parts manufactured by the company. A large number of other models of lathe are available but a woodworking lathe is more suitable than the engineering variety by virtue of its higher rotational speed.

                                                Wheel components

A set of standard turning tools is essential although many tools for detailed work can be made from old files.

WHEEL CONSTRUCTION

Wheels can be constructed according to the traditional method using felloes, a method essential if the wheel is not to be painted. The purist will also follow this system to maintain precision in the interpretation of the original vehicle; when employing the “felloe method” each felloe segment must be cut with the correct angle before gluing to provide the basis of the “felloe wheel”. It is necessary to trim the blank to an approximate circular profile using a coping saw, hand jigsaw or power band saw, once the glue has set, before offering it up to the lathe.

In the USA, and to a certain extent in this country, rims for lightweight road vehicles were laminated – a procedure which can be followed by the modeller. An accurate jig for the internal diameter of the wheel rim will be required and also beech or birch veneer strips softened by boiling or steaming.

For those without a lathe or turning facility, wheel rims can be made by a method of scribing the internal and external diameters on the basic material with a pair of compasses and finishing with a coping saw.

If the wheel is to be painted the rim can be turned from good quality multiply. It is more difficult to achieve a good final finish of a plywood-based wheel since the wood is generally more open grained. It is worth experimenting with a super-fine wood filler if the grain is coarse. Whatever the method a flat finish using the various grades of glass and sandpaper is vital if the final finish is to be good.

       Felloe blanks for turning                Turning rims                      Paring rim with home-made

                                                                                                            parting tool

The first consideration when making a “felloe wheel” must be the number of spokes and hence the number of felloes. With the de rigueur rule of two spokes to each felloe, it is a simple matter to determine the number of felloes to the wheel.

JIGS

Whatever method of construction has been decided, homemade jigs are essential to ensure accuracy.
The following jigs will be required:

· A “Hub jig” to ensure drilling the hub at the correct “dish” angle for the spoke mortices. Generally the “dish angles” for agricultural wagons will be 7° and for passenger road vehicles 2°or 3°. When making the jig it is advisable to provide flexibilty by incorporating a variety of brass tubing guides to suit several “dish angles” and stub axle sizes. In use the jig is set up in the lathe tool rest with the drill bit centred laterally on the hub.

                Hub jig with brass tubing guides            Drilling hub through hub-jig

A set of hardboard “Dividing disks” for ten, twelve, fourteen and sixteen spoke wheels are essential to ensure the accurate location of the drill bit when drilling the spoke mortices. Great care must be exercised when setting out the disks to ensure that the locating holes are accurately placed. In use a nail is passed through the dividing disk into a locating hole in the lathe headstock. A hole at the centre of the dividing disk is drilled to accept the lathe arbor.
·

                   Dividing disks                            Dividing disks fitted to rear headstock

At the assembly stage the hub and spokes are fitted into the rim. Since the hub must be at the true centre of the wheel and each spoke the same length “Sanding jigs” based on the size of the wheel, the number of spokes and the axle size are required. These are set up on a base with the hub set on a spigot. The spokes are then offered up to a sanding disk. It is absolutely essential at this stage to ensure that the forward movement of the jig is carefully controlled to ensure a correct fit.
Finally a wheel clamp may be used for the final assembly.

                               Sanding jig                             Sanding jig with spokes offered to                                                                                                           sanding disk

The spokes are formed from wood prepared to the correct dimensions, from suitable dowel (3mm plus) or from barbeque sticks. The profile can be cut after assembly or pre-formed using a profile cutter manufactured from a small piece of heavy galvanized iron. In the latter case the profile should be oversize to allow the dowel easy access. The profile may then be obtained by drawing the dowel through the cutter several times until the correct profile is finally obtained.

The spokes can be set onto the hub in a variety of ways depending upon the scale of the vehicle. Larger scales will allow the mortice and tenon method used by the wheelwrights but pins set into the hub and the spoke are an acceptable alternative for 1/8th and 1/12th scales.

The tyres are formed from brass or 'tin-can' metal fashioned to the width of the rim. A bending machine similar to that described under ‘tools’ is useful but careful hammering on a workmate/steel bar can also be effective. The length of the ‘raw’ tyre should be slightly less than the circumference of the wheel rim to ensure a close fit after the ends of the tyre have been silver soldered. Soft soldering is ineffective.

The spokes, assembled in the hub are then sanded to length using the jig and sanding plate and carefully glued into the wheel tryre.

The wheels are then ready for the final finish and assembly on the vehicle.