On Oct 6, 2:24 pm, willshak wrote:
X-posted to other relevant group.

Before there were concrete drill bits, or electric drills for that
matter, small round holes in concrete or rock were made by a round
chisel type tool that was pounded into the stone with a small sledge
hammer while turning the tool. It might have been 8" or 10" long. The
face of this chisel had a star-like pattern, only with 4 points, like a
plus sign " + ". I believe it was called a star drill.
A Google search brings up a lot of sports drills (training regimen).
Anyone know if they still make them, or if so, where to get one on-line?
I'm trying to drill some 40 - 3/4" holes in concrete and my 1/2" corded
electric drill with a concrete bit stalls on the stone aggregate in the
concrete requiring me to stop and try to crack the aggregate with a
large punch. I figured a star drill would work better.

--

Bill
In Hamptonburgh, NY
To email, remove the double zeroes after @

Yep, 'star drill' is the correct term.

The hammers used on them even have their own names...wel it is really
the name of how they are used vice the hamer itsself..

'Single Jack' - one operator who both holds the drill and hammers on
it.

'Double Jack" - one person holds the drill and another uses a much
bigger sledge hammer. That is one place where the old joke "when I
nod my head, hit it" comes from.

I even have a 3/4" one. I have tried using it a few times but gave
up. If my piddly littlel 3/8" 'hammer drill' won't cut it, it is off
to the rental to rent a big electric. The speed those things go
through holes is more than worth the rental cost.

Harry K