Glue a couple of cheap bubble levels to the Hilti.

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?