BETA-2K wrote:
I need to cut a hole in a basement concrete floor in a house that I
own so I can put in a sump pump.

I know how to do all of the sump pump stuff, but I'm not sure if
there are any tricks to cutting the hole in the concrete. The
concrete seems *very* hard (it sort seems like it's a finer texture
and much harder to chip at or break than most concrete). I have
tried drilling into this concrete in the past with a concrete drill
bit and it seemed to go nowhere.
The main thing I want to avoid is creating a crack in the concrete
while chipping or cutting out the opening. So, I'm wondering if I
could buy some kind of one-time-use circular saw blade and cut
grooves around the perimeter of the hole where the concrete would
break/crack instead of the breaks/cracks extending outward past the
opening.
I know this is somewhat vague, but any thoughts, suggestions, or
ideas would certainly be appreciated.

You can rent concrete hole saws like those use for installing below-grade
safes.