MDF Problems
I have not found a clock on the web that has been built using MDF, hopefully because it is not attractive, rather than unsuitable! The main problems with it is that it is heavier than plywood, probably by a factor of at least 25% and I've seen reports that it is difficult to sand the edges. People have also reported that the edge is not as firm as the top/bottom - and of course it is the edges that will take the strain.
I've seen suggestions that painting the edge with Rot wood hardener will help, but I shall have to test this to see if it increases the friction on the gears.
There is a product which is meant to be water/moisture resistant - MR MDF, so I shall try using that.
Seeing as most of the wheels will only be 6mm thick, instead of 12mm/0.5", I should still gain on the weight stakes.
The Minute wheel will reduce in diameter by 20% and therefore it's weight will reduce by factor of 35% of plywood - so I'll have a lighter Minute wheel as well.
When I started to work out how a reduced diameter wheel would alter the driving weight, I was amazed to discover that assuming friction etc is unchanged and also the drum diameter, then the force remains the same. Think of a seesaw balance and you will discover this is true! But we must gain slightly on inertia and less weight.
Assuming that Clayton's clock needs around 3lbs to drive it - the force on the gears will be:-
3.6oz at the edge of the Minute wheel and the pinion,
which reduces to 0.6 oz at the Crown pinion
and 0.15oz (4.5gms) at the Flags.This is all static balance weights. I'm really not sure what happens in a moving system with inertia.
Surely these figures suggest that I can use a thin Minute wheel as well, but as I've no idea what I'm doing, so I will stick with the first wheel gears being thick.
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