Making Metal Clockworks for Home Machinists. Stan Bray
(Perspex).
We all tend to think of clocks being made from brass and steel, but other materials can be used. There are a number of plans available for the construction of wooden clocks and, while this may not sound like a suitable material, it is surprisingly robust: the Germans have used it for years to make clocks commercially. Nowadays plastic can be a useful material. It is easy to work with, it is durable, and a clock made of a transparent plastic can be a fascinating thing to see. Also available are plans for clocks made from paper and cardstock (card). They appear to work very well and last for a long time.
Tools
Most of the tools likely to be needed will be found in the workshop of the average model engineer. Needle files, hacksaw, lathe, some small drills, and taps are the basic items that are wanted. In addition, a small five-sided broach is possibly the only essential item that might not already be part of the workshop equipment. There are additional tools, of course, but they are not absolutely essential. Wheel and pinion cutters could be very useful, but it is quite possible to go without them. There are many people making very fine clocks who have never bought such a cutter in their life. A depthing tool (see Chapter 6 for further information) is useful for laying out the wheels, but once more, far from essential; there are several ways of doing the job without such an item and, like cutters, they are easily improvised. Another useful item is known as a Jacot tool; it is used to obtain a high polish on pivots and as an aid to making them. It is quite possible to work without one and, if it should be thought to be an absolutely vital piece of equipment, it is very easily made.
One tool that will be essential is the five-sided broach as seen here. They are available in a variety of sizes and can be obtained in complete sets. The type shown is for cutting pivot holes; another type is available for smoothing them.
The Lathe
Watchmakers’ lathes are expensive to buy and are of little use for purposes other than watchmaking; in fact, they are of doubtful value when it comes to making clocks. Generally speaking, the type of lathe found in the average model engineer’s workshop is quite suitable. The most popular of all these are probably the mini-lathes, which have a swing of 7" in diameter. Thousands of good clocks have been made using them and other lathes of a similar size and specification. The miniature-type lathes with center heights of about half that have the advantage of being cheap and, because they are small, obviously less space is required. Most are available with a bolt-on mill/drill attachment that makes them ideal for cutting the teeth on wheels. It is not possible to give advice on the best lathe for a newcomer to purchase—it all depends on a particular preference and one’s budget. In addition, many of the foreign lathes that are sold are only available for a limited period of time before the specification is changed. Anyone wanting to purchase a lathe would do well to visit one of the model-engineering exhibitions held throughout the country, where it will be possible to browse through a large number of machines of different makes and types to find which might be the most suitable.
Generally speaking, the tools needed for clockmaking will differ little from those used by a model engineer, although one or two extra items may be required. The photograph shows a piercing saw, which is useful for many purposes, but in particular for crossing-out wheels.
A small hand clamp like this one can easily be made very quickly and is invaluable for holding small parts while working on them.
Some of the methods used by clockmakers are likely to make an experienced engineer wince. For example, while the engineer will always try and get as much bearing surface for a spindle as possible, the clockmaker seems to try to do the exact opposite. Holes that are to be used for bearings are drilled smaller than the diameter of the spindle that will fit in them, and then they are reamed with a taper broach until a fit is made. As a result, the spindle is running on the thinnest possible ring of brass. To the engineer the idea sounds frightening, but really it makes complete sense. Although the movement or mechanism is rotating continually, it is hardly going to break any world speed records in so doing. It has no real work to do inasmuch as it is only driving itself, and so the small bearing surface has the advantage that it cuts friction down to a minimum. As a result, it reduces the power needed to run things.
Terminology
This is another thing which engineers may find a little difficult to understand. A shaft or spindle is known as an arbor and the bearing surface at the end is not a shaft or axle but a pivot. Gears become wheels in spite of the very obvious teeth all round them, the making of which is the main part of clockmaking. Although the teeth on the wheels are called teeth, when they are on a pinion they are frequently described as leaves. These gears (wheels) are made of thin section brass, which is ideal for the mechanism that is being constructed. In order to give a good fit on the spindles (arbors), they are fitted on bosses, from now on known as collets. To an engineer, a collet is something that opens and closes to hold tools or material. To a clockmaker, the term includes the length of brass used to support a wheel. And, finally, there is the mechanism itself, which is called a movement. It is all very confusing at first, but we must remember that every trade has its own terminology—just look, for example, at those used by the computer engineer.
Two members of the British Horological Society at work in the workshops. The photograph gives some idea of the type of bench to aim for. A clean surface, a tray for parts, and a good light are the basics, with some small storage stands for the few tools required.
Generally speaking, any lathe will do for clockmaking. The photograph shows the Cowell, which has been specially designed for the purpose.
Help and Assistance
There are a considerable number of plans available for making clocks of various types. Some, such as the designs of John Wilding, are sold in book form, complete with full instructions; they are very highly recommended. Other similar books are available as basic plans, and in some cases complete kits can be purchased. The photograph on the front cover of this book is one of a movement made from just such a kit, by Repton Clocks, and this, too, is an ideal way to learn the basics of clock construction. There are also a number of suppliers of clock parts and books based throughout the country.
The British Horological Society stocks a wide range of books and plans. Here we see a photograph of the library, possibly the most extensive in the world on the subject of watches and clocks.
If we accept all the oddities that are imposed upon us, clocks are fascinating. There are no heavy castings to hump around, the work is nice and clean, and the end result is worthwhile. Even if after reading this book the reader should decide that clockmaking is not for him or her, it is still worthwhile taking an interest in them, their history, and the beauty of the finish on many. This in itself can provide an everlasting interest.
This book deals with simple clockmaking techniques; it is possible to progress further to such things as striking clocks or, perhaps, as seen here, an orrery, which gives the rotation and phases of the moon and planets in relation to the world.