To: atm{at}shore.net
From: Anthony Stillman 
Reply-To: Anthony Stillman 


Now there's no scope, nor mount, nor equlitorial head coupling, and the
patio bricks still aren't back in place, but the pier and riser are up.

The riser is made from an open bottom cinder block (on end) and a 12 inch
round concrete stepping stone (on top).  The pier is tied down to the
foundation with four 2 foot lengths of 5/8 inch threaded rod.

The stepping stone is cracking.  It appears the bolts are putting the stone
in tension over the a corner and an edge of the cinder block.  Tension bad,
compression good, but how to fix this. Ideas?

I checked the pier's secureness by grabbing the top and bracing one foot
against the top of the raiser.  I'm not broken so I think it's OK.

To check for vibration and dampening, I smacked the pier with this and
that, here and there, then watched, felt, and listened.  As expected the
issue is low frequency vibration.  By look and feel, it appears to damp out
in two to three seconds.  I duct taped a 60 mm f/12 refractor to the pier
top.  Viewing a distant street lamp at 100X the vibration damped out in no
more than six second.  Also, by observing the pattern of ons and offs in a
spinning image of the street lamp, I determine the principle frequency of
vibration to be about 13 Hz.  I bounded it as being between 10 Hz and 15
Hz.  From this, I infer that unloaded, the pier damps out in less than 100
cycles (6 sec. X 15 Hz). Still less would be better.  But how?  Suggestion?

There's lots more detail and "opportunity."  Like, how to protect
the "I can't afford stainless steel" nuts, bolts, ....

Anthony


quid rides?
Why are you laughing?

--- BBBS/NT v4.01 Flag-5