Design Considerations

 

Overview: As I had it in mind to make the clock transportable so it could be taken to various shows or moved to different places in the garden, I decided to make the clock in four sections:

  • The main clock tower with removable sun unit,

  • The carousel unit with yacht and dove-on-a-pole. This is bolted on top of the clock tower,

  • The synthesiser pulpit bolted to the right of the clock tower,

  • The minaret and tub bolted to the left of the clock tower.

 

All sections in contact with the ground will be raised off the ground on castor wheels. This will make it more manoeuvrable and will stop the damp from seeping in underneath. It may also help to keep rodents out (?) but how I will stop spiders from entering I have no idea!

The power for the unit will have to be from a mains supply. Internally, everything will be 12 volts dc, so there is the potential to run it from a car battery if necessary. There will have to be an emergency stop button accessible in the front to meet health and safety requirements. Everything would be controlled by a cheap micro-controller board housed in a weatherproof enclosure on the rear of the clock tower – more on this later.

Like the original clock, music will be played at various times, as already mentioned, so a loudspeaker system and amplifier will be installed in the main tower. I didn’t want it to sound tinny, so it will incorporate a separate bass unit in addition to two stereo speakers all driven by a reasonably powered Class-D amplifier system.

For a project of this undertaking to be worthwhile, it needs to be able to endure the British climate. I also want it to last at least 20 years. So I spent some time researching materials that would be waterproof, non-fading, mildew and warp-resistant but light-weight an inexpensive.

Frame: I am much more adept at woodwork than metalwork, so the frame I therefore decided to construct from 40mm x 40mm Douglas Fir as it is medium-weight and, in comparison to other coniferous woods, fairly hard. It is subject to low shrinkage, has good stability, and is strong and elastic. The wood is also resistant against fungal and insect infestation and exhibits good natural durability when exposed to the elements. All the timber will, however, be behind cladding and will be treated with a wood preservative. Fortunately, I found a good local supplier at a much cheaper price than anywhere else!

Cladding: The cladding could have been sheet metal as in the original clock, but I have had some experience with a plastic foam board material called Foamex, used for signs. At 5mm thick it is very lightweight, waterproof and easily cut to shape. It is remarkably strong but could snap under extreme pressure. I have a good local source of 8’ x 4’ sheets of this material and at a good price. All joints will be made watertight by slotting into plastic mouldings or by silicone sealant. Most panels will be removable for access and maintenance.

Douglas Fir used for frame.

Foamex' cladding.

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