Have you googled for "Fence post spike"

What's a post spike?

A post spike is a heavy metal spike about 24 or 30 inches long with a metal
box (usually 4" x 4") attached to the top, designed to hold the base of a
wooden fence post. You simply drive the post spike into the ground where yo=
u
want to put your fence post and then insert the wooden post into the box.
The idea is to provide a convenient and economical way to build a fence - n=
o
need to dig holes and pour concrete, and the post spikes only cost a few
dollars each.

I've used them and they are simple to use.  If they aren't rigid enough the=
n
add guy wires.

Gordon Williams




----- Original Message -----=20
From: "RussellMc" <apptechnz@gmail.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Thursday, January 27, 2011 7:05 PM
Subject: [OT]:: Better cheaper faster fencepost anchoring ideas wanted.


> Summary:  Creative ideas wanted  for cheap, quick, robustish [choose any
3]
>  in ground mounts for "very tall fenceposts".
>
> I wish to build a number of short term "towers".
> 2 to 3 metres high.
> Robust enough that a strong man couldn't easily push one over.
> (That's an arbitrary strength measure but gives some idea).
> Some could be weaker. Any stronger and formal methods probably apply.
>
> I'm looking for "lightbulb"  ideas for anchoring these in unprepared
ground
> (dirt) with minimum effort and cost, good rigidity and ideally ease of
> removal.
>
> Any number of "common sense" / everyday solutions are available. A few -
>
> Hammer in post,
> weighted frame,
> Dig a hole, (augur, spade, hose!...)
> hole with concrete,
> hole with wedges,
> Warratah (antipodean metal 3 rail ground anchoring fence post)(named afte=
r
a
> rather tough Austalian plant),
> guys with anchors, (soil anchors, screws, ...) ... . I
> props,
> ...
>
> BUT somebody may well have a "why don't you just ..." idea.
>
> eg tyre filled with concrete, water filled ..., frame from a ... , ...
>
> Using a car is not viable in this context.
> Anchoring is good but size, availability of N, wind obstruction, cost,
> difficulty in getting it out of the  garden afterwards etc preclude such.
>
> Aim is to support very very very small wind turbines for testing in a
range
> of circumstances.
> Support height is usually low - maybe in the 2 to 3 metre range above
> mounting point.
> (Note: that is NOT what you should be doing usually with any sensible WT)=
..
>
> Target wind speeds are low - say under 10 m/s (20 mph / 30 kph) max and
> usually much less.
>  Forces are in most case small by WT standards. Upper size would have
> perhaps 1 m^2 swept area BUT this would be effective only at low win
> speeds.
>
> As a guide, using f ~~~=3D 0.65.A.V^3   (Newton, m^2, m/s) at sea level
> You get about 65 kgf per m^2 at 10 m/s
> 65 kg side 'force" at the top of a 3 metre tower
>  ~=3D 200 kg.m torque
> would be 'challenging" [tm].
>
> In most cases I'd be dealing with much much less than that and by the tim=
e
I
> got to that upper extreme I'd be looking at more formal means.
> Force rises as V^3 (see above formula) so at very high wind speeds no
simple
> solution is going to work.
> That's not relevant here.
>
>      R
> --=20
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