Rob Morley wrote:
In article , "AlexW"
says...
snip

Yeah, IIRC these are about £20 from wickes, my concern here is that
these are quite light approx 5 kilos I think ... will this give me
enough compaction?

I am also a bit worried that I might struggle with this type as the head
is about 10cm square and it might push the chippings around the sides
rather than down to a degree, where as with a wider plug this effect
will be lessened?


Only because you're spreading the force over a greater area, and the
proper tool will be easier to keep straight.

I have never used one of these but have used sledge hammers up turned
for this sort of thing and the chippings do tend to move (like a dulled
down splash) ... my worry is that on the surface at least a sufficient
compaction will not be achieved. Gut feeling tels me a wider plate would
work better, but requires proportionately more force, hence heavier
weight.



I know there will be a trade off between the weight and velocity of the
pound due to my physical ability lift and pound the heavier device.


Remember kinetic energy is proportional to the square of velocity, so
if you accelerate this downwards with a force of 1g in addition to
the acceleration due to its weight, it will be the equivalent of
dropping 20kg the same distance - and you'll be able to lift it
higher and use it longer than your 30kg lump of concrete.

Yes. Maybe 15kg would be better then? assuming This can be lifted to the
same height then and accelerated sufficiently. I won't need to work it
all day or anything in either case. The areas are relatively small.

Cheers,

Alex.