On Sep 25, 8:53 pm, wrote:
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?

Do what mechanics have done for years: make a drill guide. Many ways
to do it, like use a drill press to drill a straight hole in a 2 x 4
for example. position it on the ceiling supported with a couple of
those screw jack thingies that cabinet installers use, or simply cut
the right length 2 x 4 to wedge under it. If you've got hundreds of
holes, have a machine shop make you a drill guide out of a steel plate
with the welded on guide piece sticking up out of the middle. Again,
support any way that works. Either way your job will go ten times
faster and dead true. HTH

Joe