Thanks to Jon Bogstand for your input on another thread re: my new twice full size "duck" I will try not to make the same mistake as I did with my first largish (8kilos) stationary steamer.

I doubled the dimensions on that one as well only to find that the completed crankshaft was badly out of balance. I had not taken into account that doubling the dimensions of the crankshaft webs was completely the wrong thing to do. The right way should have been to double the weight ? NOT the dimensions. i.e.: A one inch cube of mild steel weighs .2833 lbs. Double the size to a two inch cube and you get not 2 x .2833=.5666 but 8 x .2833=2.2664.

I put on my dunces hat and stood in the corner while trying to remember the formula for calculating the volume of a cone ? what a dimbo!!

Stuart