"Between 1800 and 1850 some hundreds of thousands of ‘shelf clocks’ were made in New England almost entirely of wood. I have one of these, made about 1830 at Bristol, Conn. Except for the brass escape wheel, all the wheels and pinions of both going and striking trains are entirely of wood. The pivots are of steel wire driven into the ends of the arbors, and they turn in holes, drilled through the wooden clock plates and not bushed. Though the clock has been going for over a hundred years, it is practically as good as new: there ars no signs of wear on the pinions or wheel teeth and the pivot holes have not been bushed and show no signs of wear. Some black smudges on the plated suggest that graphite has been used at some period to lubricate the pivots. Many of these clocks were exported to England and are still in use. A few are in museums, and thousands are still going in American homes. They show the fallacy of supposing that friction and wear can be avoided only by the use of hard materials."

Extract from page 306, ‘The Science of Clocks and Watches’ by A.L. Rawlings. Third Edition, published by Longman Group UK Ltd and the British Horological Institute Ltd, 1993.

The Use of Wood in Clocks

Will Matthysen is sometimes asked the question whether wood is a suitable material for making clocks. His response is generally along the lines that it is no more or less suitable than the use of wood in violins, harpsichords, woodwind instruments or tables and chairs for that matter. What is important is the appropriate selection of wood species, how it is milled and seasoned, and the joinery details of the various components.

The type of wood used in the American shelf clocks described by Rawlings above would have been a variety of local species, largely dependant on availability. Clock plates were often made of American oak, with the wheels and pinions in a fine grained fruit wood such as cherry. Black Forest clocks of the mid 1800’s tended to use European beech. John Harrison’s H1 chronometer used quarter-sawn English oak for the wheels, and lignum vitae for the bushes.
Will Matthysen takes great care in selection and seasoning of the wood used in the construction of his clocks.

Quarter sawn wood is inherently more stable than back sawn material, and hence is preferred for use. Similarly, the wheels and pinions are arranged along the length of the grain, given that wood shrinkage parallel to the grain direction is minimal.

But most critical of all is the timber drying and seasoning procedure. The process here is to pre-dry the material to a moisture content well below that of the environment that the clock is likely to end up in. Will re-saws his air-dried timber into the approximate sizes of the various components, and then places them in a heated drying cabinet for a number of weeks to bring the Equilibrium Moisture Content (EMC) to around 7% to 8%, and then removing them from the cabinet and letting them reabsorb moisture to workshop conditions, and preferably repeating this process a few times, before further machining and assembly.

The wood will now have an EMC below that which it would normally have if it was loosing moisture. This is known as the hysteresis effect, and minimizes the subsequent expansion or shrinkage in future, making the wood more stable.

"A violin, for example, can be in Honolulu the one day and in Helsinki the next without falling apart. Traditional craftsmen understood this process intuitively, even if they did not understand the science."

"Part of my interest is to find relatively obscure Australian species that are suitable for use in clockwork".

In particular some of the Outback acacia species are particularly slow growing, dense and stable and are suitable for a variety of mechanical applications, such as wheels and pinions. These wood species include:

Gidgee (Acacia cambagei),
Mulga (Acacia aneura),
Myall (Acacia pendula),
Leopard wood (Flindersia maculosa),
Belah (Casuarina cristata).

The clock plates and the rest of the clock cabinet can be sourced from a broader variety of Australian timbers, with the selection based not only on mechanical properties, but also on aesthetic considerations such as colour, grain, texture and figure. A small sample of the species used most often includes:

Jarrah (Eucalyptus marginata),
Redgum (Eucalyptus camaldulensis).
Red Box (Eucalyptus polyanthemos).
Red Stringybark (Eucalyptus macrorhyncha).
Red Ironbark (Eucalyptus crebra) , Mountain Ash (Eucalyptus regnans).
Huon Pine(Lagarostrobus franklinii).
Black heart Sassafras (Atherosperma moschatum),
Myrtle Beech (Northofagus cunninghamii).
Blackwood (Acacia melanoxylon).

"This continent abounds with rare and beautiful timbers that are still waiting to be explored. There are over 5300 wood species native to Australia, with about 1200 acacias and 700 eucalypts. At the moment I feel I have just scratched the surface...The ultimate would be to produce a working timepiece, the size of a pocket watch, made from native bush timbers."