>Hmm, a rotor hammer drill sounds pretty fierce. I don't suppose a
>black and decker 3/8" hand drill is going to cut it.. What about a pretty
>beefy 1/2" drill that I can borrow from work??
Probably not. Trust us. Been there, done that, burned up a LOT of bits
trying. We used the expansion bolts like Mike described when we built our
wood shop in the back yard several years ago because the guys who did the
concrete work for us forgot J-bolts that could have been put in place as
they poured the slab. We were able to borrow a construction grade hammer
drill and were able to drill for and install around 20 5/8 bolts in a
couple of hours.
That was in new concrete. Concrete gets harder with age. I had to drill a
couple of 1/4 holes about 3 inches deep in our bathroom floor recently. I
used a standard heavy duty 1/2 drill and wore out four new Bosch carbide
concrete bits in the hour it took to drill the two holes. If I9d realized
how much trouble it was going to be, I would have rented a hammer drill.
The contractor friend who loaned me the big hammer drill for building the
shop offered an alternative to the expansion bolts. This method was used
to secure a compressor with an 80 gallon vertical tank. After marking
where the mounting feet on the tank sat on the concrete we drilled four
holes 6 to 8 inches deep, but out from the base at a sharp angle rather
than straight down. Then we inserted threaded rod into the holes and bent
the rods straight up from floor level. I think we may have injected some
epoxy concrete patch to help hold the rods in the floor, too. Ran a nut
down on each of the rods and then used a die grinder to cut off the
excess rod. Took the nut off to clean up the threads and then placed the
compressor down over the bolts and added washers an put the nuts back on.
Both methods work well. I think the second is particularly good for
installations where there may be considerable vibration, like a
compressor. Regardless of which way you do it, using a hammer drill will
make the job much easier and quicker.
FWIW, Ron
Ronnie Day
ronday@home.com
Dallas/Ft. Worth
'71 510 2-dr (Prepared Class Autocrosser)
'73 510 2-dr (Street Toy)
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