Thanks Jason, the extension looks a good one but, as you suggest, I think I would need to grind a flat for the grub screw as with a bit, of the diameter I need, would exert a fair amount of torque.
I need to drill lengths of wood approximately 10inches and around 1inch dia. is there a really good extension system I can fit to a Forstner bit? Or any ideas as to how I can do this?
I have had a cistern with a push down knob on its lid. It's has been erratic to operate since new, no matter what adjustments I have made. Is it posssible to fit the newer push button style to an ordinary cistern?