"klim" wrote in message
...
I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in
solid rock for steel T-posts for a fence and I haven't decided how to
go about it.

What type of bit/drill combination would be most cost effective?
Electric drill (size?) with core bit?
Pneumatic drill with impact bit?
Other combo?

The location is far from power so the job would require a portable
generator or a compressor if a pneumatic drill was used.

I have a 2hp 20 gallon compressor - would be sufficient to run a
pneumatic drill to drill the 1 1/2" holes?

You do not mention the type of rock. That makes a big difference.
Electric, Hilti or Bosh your going to need the biggest badest one they have.
You will probably wear it out when your done.

Pneumatic, You could let it run for a week, and probably burn it out and
still not have enough air for a pneumatic hammer. I used to work on a line
truck digging holes and setting poles. There was a air compressor on board
and a 90 lb pneumatic hammer. Set the truck rpms to 1800, then engage the
air pump by the PTO. Wait a few minutes and go to work. Took 20-30 minutes
to drill a 2 inch hole in granite 2 feet deep.

I do not think that the 6 inch holes are deep enough for a regular fence
post. More like a foot or more will be needed.

Have fun your in for some long hours.