New to List. Granite Problem

[William Cowan <william@zzzzzzzzzzzzzz>]

G'day All

This is my first time here, so please go easy on me.

I have a large granite boulder which I want to break up. It sits up above
ground level 400-500mm (18") and is about 4 meters (12') across at ground
level. It's mostly buried. It is just this top crown I want to break up.

The granite is VERY hard. A large sledge hammer will bounce back off the
surface about as quickly as it went down. A small hammer drill will not even
drill a 1/4" hole in it. A Hitachi non rotary demolition hammer does not
make too much of an impact on the surface, breaking off only the occasional
chip.

I understand the best way to break up granite is by drilling a series of
holes in line with the intended break (within 10 degrees of horizontal in
this case), Then using feathers and wedges to force the rock apart. I will
purchase a hammer drill to do this job, but are unsure about how large (read
expensive) this hammer drill needs to be. I don't want to buy a tool that is
not up to the task, and I don't want to buy a tool that is way too big for
the job. Is a hammer drill like the Makita HR3000C up to the task or will I
need something along the lines of an AEG PN11E ? What electric hammer drills
do others use successfully to drill granite?

If I am not interested in a clean break, are feathers and wedges essential,
or will tapered steel spikes be sufficient to get a break?

Any other ideas you can offer would be greatly appreciated.

Thanks in advance.

William Cowan
William Cowan		38 Carr Cres		(BH) 612 6201 7956
Cowan Audio		Wanniassa, ACT 2903	(AH) 612 6231 4719
http://cowanaudio.com	Australia		(MOB) 0407 078 555