PSN-L Email List Message

Subject: Seismometer Basic Frame Construction Thought
From: "meredith lamb" mlamb1@..........
Date: Fri, 15 Dec 2000 11:52:56 -0800

Hi all,

We've all seen alot of the same general "swinging gate"
seismometers construction method....i.e., the major pieces
being the flat base plate and a mast attached to it.

I suppose thats all well and good....if.....the amateur builder
is lucky enough to obtain thick enough, or enough
reinforcement additions to make it stable, to avoid alot of
operation adjustments.   This is a definite challenge to do.

I've made a number of Shackleford-Gunderson seismos that
more or less use a "box" frame aspect that are a different
approach obviously.  Admittedly with using steel and
aluminum, they do take a month or more to mechanically
settle down or stabilize themselves, for a more consistent
operation thereafter.

The main thought I bring here, is nothing more than
intertaining the though of using the same approach for the
more typical "swinging gate" seismometer and its base
"frame" variation.  For example:   "If" one has a box (of
whatever material), it would be likely to be more
structurally stronger than the typical flat base plate and
mast usually utilized by amateurs.  The key here is
obviously finding the strongest material
could open alittle more options for amateur builders.  With
such a frame, it would be much easier to add support braces
if needed.  Naturally, the seismo boom/mast/mass and sensor
method would have to be configured for use within such a

Its also possible to envision such a "frame" or "box", being
possible with only 4 sides being utilized, without the top and
bottom....or....the complete "box" of 6 sides, but this is
dependent on the strength of the material joints, thickness.
Naturally one side would have to allow access.

Going further....."if"  I were deprived of say, thick aluminum
or other metals material, or cost limitations/budget; and the
desire is there....I would "go for" whatever material I could
afford....even it was a thick WOOD frame approach.  Of
course, I'd use a sealer/paint to give some more stability or
freedom from moisture absorption.

Perhaps the only other positive aspect of this approach,
could be the simple addition of insulation on the inside and
outside for additional thermal variation protection.

This idea is not original, I'am sure, but I've yet 
to see any seismometer using this...outside of a "SG"
type design.  Perhaps others might have other limiting
application objections...or have even tried this???  

Meredith Lamb


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Larry Cochrane <cochrane@..............>