In article ,
T i m wrote:
Hi folks,

I'm trying to make a special drill for drilling out the stump of
a 9" sq wooden gate post but want to leave the surrounding
concrete intact.

Bizarre sideways thought.....

Could the stump be pumped out hydraulically,
or at least freed enough for a straight lift?

Drill one hole down the centre, about an inch dia,
and right through the bottom. Fill the hole with
water until it will take no more. 1 inch steel
bar as the piston, and a sledgehammer.

--
Tony Williams.