wrote in message
ups.com...
I'm using a Hilti drill to drill holes into concrete ceilings.
Drilling overhead with a heavy drill and big bit is making it
difficult to keep the hole straight. The Hilti is more than up to the
job ... the problem is when you're applying upward force, the natural
tendency is to pull the drill toward you or away from you, which makes
for a slanted or "crooked" hole. Any tips on how to keep the drill
straight so as to achieve the straightest possible hole?


Kinda depends. On how straight it HAS to be, and how much time you have to
drill X many holes in a day, how many of these holes are you going to drill
and how frequently, and how much equipment you have on hand.

If I (underlined I) had to drill some holes for my own use, I'd get a piece
of 4 x 4 and drill a hole in that. Then I'd drill a starter hole in the
concrete, slide the 4 x 4 on the bit, put the 4 x 4 flat on the ceiling, and
drill a reasonably straight hole.

If it had to be EXACT, I'd put the 4 x 4 on a couple of screw jacks.

If I HAD to drill a bunch of holes every day, I'd make a drill holder (I'm a
welder), and could do that cheaply. One could easily be mounted to the top
of a screw jack and moved in a couple of minutes.

If I were a craftsman and had to do this a lot all the time, I'd have a
welder make me a drill guide, and do consistent accurate work.

It really all depends on how accurate you have to be, and how often you have
to drill the holes.

The 4 x 4 idea would be the hobbyist approach, easy, cheap, and reasonably
accurate for a few holes. Plus, you could keep it on a shelf for future
use.

From there, if it has to be accurate, and it's going to make you money, DO
IT RIGHT THE FIRST TIME.

Steve