Jonnyh

I know exactly what you mean and that was my first concern with putting a bigger hand wheel on my leather sewing machine, believe it or not I had luck with taking a pulley off of a gas-powered air compressor. It's a little over 10 in in diameter and also balanced and it's nice and heavy duty cast iron, just look around for the old compressor pumps with the good size flywheel on them and they are most likely balanced.