On Sat, 13 Apr 2013 14:59:56 +0100, unknown wrote:

Previously I've just used a spade to dig-out holes for concrete spurs
but I'm tempted by either an auger or a "post hole digger" ... which
works best?
These are available from several places; the SF ones get good reviews
but look a bit expensive compared to the others ... is the extra cost
justified?

Supplementary: how much postcrete am I likely to need when setting a
75x75 spur into a 600x150'ish round hole? (I know I could do some sums
but in this case I think benefitting from experience is going to give a
better estimate)

As others have said, it depends on the ground!

I bought an augur.
It was no good in gravel or sandy soil and I gave it away on Freegle.

I now use the 'two spoons tied together' tool for removing waste from the
hole when it starts to get deep.

To dig the hole I start with a spade - also a trenching spade which is
good for keeping the walls of the hole reasonably small.

If the ground is soft I then dig out with the post hole digger described
above.

When we did the fence here with concrete posts a few years back the sandy
ground was so dry it was like rock and we had to break it up with a long
iron bar before digging it out.

I use PostCrete or similar, about one bag per hole (depending on how
vertical the sides of the hole are I sometimes get away with two bags to
three holes).
There are cheaper ways but it just does the job with no hassle.
You don't have to fill the hole completely - just get a lump of concrete
which grips the post at the bottom and grips the ground around it.

Cheers

Dave R