The Use of Wood
Great care is taken in the selection and seasoning of the wood. Quarter sawn wood is inherently more stable than back sawn material, and hence is preferred for use. Where the wheels are made of wood, the wood is cut into segments and then glued to form a ring where the grain runs parallel to the tooth of the wheel, giving it maximum strength. The wheels and pinions are mounted on steel arbors, and the pivots run in stainless steel and ceramic micro ball races to minimize friction. The entire clock movement can be dissembled for future service of repair, and is fully adjustable.
The timber drying and seasoning procedure is extremely critical. 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 be used. 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 losing moisture. This is known as the hysteresis effect, which minimizes the subsequent expansion or shrinkage in future, making the wood more stable.
Will is interested in finding relatively obscure Australian species that are suitable for use in clockwork. In particular, some of the Outback desert Acacia species are extremely 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.
- 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)