On Sun, 26 Mar 2006 13:23:53 GMT, Ignoramus5876
wrote:


So... What's a good way of mounting a mailbox post? Maybe I should set
that mailbox post support at least partially into concrete? (ie, digh
a shallow hole, beat it into the hole level with ground, and fill the
hole with concrete?

This is my basic design, just have to get a Round Tuit to do it:

About a four-foot length of Well Casing or 4" square extra-heavy
tubing for the mailbox post, with a 12" square of 1/2" HRS welded to
the bottom. Four 3/8" holes in the corners for the shear bolts, and
eight gusset plates pocketing each corner shear bolt so the plate
doesn't bend (much) while the bolts are shearing. And a hole through
the middle of the plate into the tubing for the restricting device.

For the base, a concrete footer around 24" diameter by 3' or so deep
- you may need to go deeper to get below the frost line, so it stays
put from frost heaves. (Concrete is cheap.) A simple rebar cage, and
8 or so heavy foundation J-bolts with double nuts for leveling. Set
the bolts up high enough so you have a 1" gap to get a stick with a
nut underneath.

And in snow country don't put the top of the J-bolts above average
ground level, so the plow blade can't hit them easily - better it
should be a bit low. (I thankfully don't have to worry about that.)

The bottom plate for the footer is 16" square by 1/2" HRS with holes
for the foundation bolts around the edge, and four holes in the
corners of a 11" square to mate with the post baseplate.

And some sort of a restrictor to try and keep the sheared off post
in the same county - a piece of slack chain or aircraft cable coiled
up inside the post, hooked to both halves with shackles, and anchored
to the top cap of the post that is removable for servicing. Perhaps a
garage door tension spring at the post top cap end to slow it down
gradually at the end of the flight path.

If someone hits the post dead-on and hard, they just shear off the
3/8" bolts holding the baseplates together, and it gives way just like
a fire hydrant - but without the instant fountain... Put it back
upright, and bolt it back together. To apply the nut under the plate,
you hold it on a paint stir-stick with some double-stick tape and
slide it under, followed by an open-end wrench to tighten once it's
threaded. Simple and slick.

The chain or cable keeps the flying box and post from going into LEO
or through the neighbor's window. And if they REALLY do a good job
and screw up the baseplate, you can unbolt the bottom plate from the
concrete footing and devise a Plan B.

I will also have a PVC conduit through the footer stub up at the
baseplate center hole for future low voltage wiring. One circuit for
a "Mail Here" chime connected to the box door, another for a
decorative 12V light on the top of the post and/or a lit address
number sign, and a normally-closed circuit for an alarm - "Gee, the
mailbox isn't there anymore."

The switch and light wiring is sacrificial, the restrictor chain
going through the same hole will snap it and chew it up if the mailbox
ever takes wing. So be sure to place a buried splice handhole in the
lawn near the footer so you can repair it easily.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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