Broke the third crank mechanism! The dome is just too heavy! I wore out two round holes for a crank handle into oblong holes in just a few complete rotations. Two 1/2 inch holes through mild steel rhs turned into 1/2 inch by 1 inch oblongs.
So now i have built a SUPER CRANK MECHANISM out of two 25mm roller bearings side by side. I'll be getting Ron to put it on the site for me, on the support ring page.
hello baz, i hope that works out for you. if not could the chain be altered to run under the gear at the crank handle? it would change the stress point from pulling horizontally to pulling upward
Reducing the size of the drive sprocket by 2 teeth for example , it appears to have approximately 20, will reduce the effort required to turn it by around 25%, but will introduce higher stresses in the crank mechanism...
