on 10/6/2007 6:05 PM PeterD said the following:
On Sat, 06 Oct 2007 17:24:26 -0400, 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.


I'm 100% sure they are available, but I really don't think many 1/2"
corded drills will do much for you.

These are impact, so you need an impact tool.

I use an IR tool that uses star bits, works nicely (but is air
powered!) I know you can rent electric ones (or buy, but they are
expensive).

But using a star drill in a standard drill won't do you any good,
you'll never really make a hole--you have to have impact.

I have the small sledge hammer. I just want the hand tool star drill.
I'm not going to try to put it in the electric drill. When the electric
drill with the concrete bit just spins on a bit of aggregate I can use
the star drill to break up the aggregate.

BTW, with my
IR tool, I provide the rotating force, the tool only provides the
impact. And if I don't provide rotational force, things get very
strange after a short while! (I usualy do a continous 90 degree
rotation back and forth as I'm drilling...)

And, yes, the star drill will work better. I punch 3/4" holes about
three inches deep in about a minute or so per hole.

Try a tool rental place. Tell them what you need, they will have
something to do it.



--

Bill
In Hamptonburgh, NY
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