On Thu, 4 Jun 2009 14:40:40 -0700 (PDT), moghouse wrote:

Frankly none of the above. Go to your nearest tool hire company and
tell them what you want to do. They will have a post hole borer you
can hire that will do the job with the least effort and greatest
efficiency.

I'm not sure I'd like to try holding a powered borer on my own. I think
they are really a two person device. A lot will depend on the local soil
conditions, few stones or rocks and just "earth" might not be to bad.
Heavy clay or scattered rocks could be interesting when the bit jambs and
the engine rotates, or tries to.

Yes you must make the hole bigger than the post so that you can put some
concrete in it to hold the post securely particularly if they are nine
foot posts!

Don't see 'em putting concrete around telephone or power poles... Snug
hole with rammed soil/rubble around will hold a post, provided it's put in
deep enough. A 9' total post needs a minimum of 2' better with 3' in the
ground to be stable. If the ground is very light and soft you may need
more depth.

"Postcrete" or similar poured in dry around the post in a snug hole and
settled in by waggling the post and a some tamping is less effort than
ramming earth. The damp in the soil will set the 'crete and the post will
be held before it's set anyway.

--
Cheers
Dave.