Hi Ian,

For myself and likely for you, alot about making a pier/s
depends on you; how much you can do or want, your space,
your soil/rock underneath, picking a "quiet" location away
from most upstairs traffic/tilt/furnace/washer/dryer, away from
too much water moisture seeping in, running in the signal/power
lines and with consideration of whether you can physically do
it all.  Only the individual can estimate/acquire/judge their specific
plus's and minus's of their location for making their own piers
of course.

As for your specific pier dimensions question....it depends on
what you plan to have or have in your possession now.  Of
course the pier has to be a greater size (width/length) than any
seismo you have or is planned for.  Mine are rectangular, but I
see no problem with round piers....they might be better.
Generally I would say the bigger the better.  As for thickness,
I'd give at least 6" if possible....the thicker pier would be less
prone to cracking from environmental influences and weight
put upon it....you've likely be standing/kneeling on it occasionally.

Another important thought to add to the mix of questions....is
whether you want more than one pier per instrument you have
or are planning for.  I made 3 piers, but now wish I'd made
more.  However, it "maybe" possible to share one pier with
more than one instrument...another consideration as too the
size of the pier.  It may also be evident with multiple piers,
that you find that certain piers are more susceptible to tilt
than others you have...I'd put the vertical/s atop the more
susceptible tilting pier and the horizontals atop the more
stable ones in time.

Assuming you survey your available area....the next step
would be to do a test dig in your soil.  If the soil is real loose,
how far down does it become more compacted than it was
on top?  If its loose no matter how far down you go....you
may have to settle for that depth.  If you run into a water
seepage pothole, thats not good.  If you run into solid rock,
thats great; as its about the best foundation you can have.
Of course, the height of your seismo/s is another consideration
to plan for, and also the available anticipated height of your
pier from the underside of the house, just for clearance.  Their
is alot to consider overall.

Another problem might be whether you want a solid poured
concrete pier or have to improvise with paving blocks and
brick mortar.  If space for movement is limited, or its physically
too difficult to mix concrete under your house or move such,
you may have to be forced to choose between the two.  One
can only do whats possible in the end for their circumstances.

Adding to the above.....is the likely necessity of enclosing your
piers with a wall/box, and adding any insulation to try to limit
any gross environmental temperature excursions you may have.
Insulation does help alot.  I ended up with a rough R42 value,
except for the ground area....its the coolest place I have even
in high temp summer conditions.  The vault floor is double
covered with flexible plastic layers, to keep water/moisture
out; and it works well...no rust either that I've noted on the
seismos and misc iron/steel tools/parts therein for some ~7
years of use.  I don't use any electric heating or temp control;
all the heavy insulation seems relatively temperature consistant
and/or very slow changing over time....a real help.

So....there is alot to mentally "chew on", or plan or inspect for.

Take care, Meredith

ian@........... wrote:

> a few dimensions would help, width, length and depth of the peer.  I hope to be
> making one in the next 6 months.  Does the peer have to be the same size as the
> platform it supports all the way down or can it have a small circular cross
> section?
>
> TIA
>
> Ian Smith
>


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