Re: ATM "Frozen" liquid mirrors

[PAugello@aol.com]

FWIW:
     I've worked on this problem quite a bit over the years, with my
turntable.  Starting at the bottom, this is where I am (right now!):
     Brass disks on the floor, with hardened steel points resting on them.
 The points are in the bottom of a three-legged tubular steel stand, which is
filled with sand.  A 24"x24"x7" open-topped plywood box is atop the stand,
which has 3" of sand, then a 18"x18"x4"  125 lb. marble slab, and then sand
in the sides, if you know what I mean.
     Next come the pneumatic isolators.  Tennis balls worked well here, but
needed frequent replacement.  I fooled abound with inner tubes, but nothing I
tried worked as well as the Tennis balls.  The laboratory isolators I'm using
now (from Newport, BTW) work very well.
     Atop the isolators is another block of marble, with three 10 - 15lb
blobs of lead on it.  I used Mor-Tite, the rope caulk, to attach the lead.
 Pennies are resting on the lead, with the spiked feet of the turntable on
them.  The 'table is self has no suspension and weighs about 125 lbs,
including the 80 lb lead platter, which is supported by an air-bearing.
     Obviously, playing a record is an extremely demanding test of a system's
rotational stability, its ability to isolate external vibration, and to
disipate and/or transmit self-generated energy.  The last thing I added was
the sand-box and lower marble block -- what surprised me the most was the
level of improvement wrought, especially considering the somewhat heroic
lenghts I had already gone to.

Hope I'm not straying too far afield here....
Peter Augello


In a message dated 97-02-21 13:42:46 EST, khillig@Chem.LSA.UMich.Edu (Kurt
Hillig) writes:

<< A sandbox on inner tubes - even a couple sheets of plywood laminated
 together - would be better than concrete! >>