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Posted by willshak on October 6, 2007, 7:57 pm
on 10/6/2007 6:05 PM PeterD said the following:
> 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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