PSN-L Email List Message
Subject: Re: Reinforced concrete base for Lehman instrument
From: "David H. Youden" dyouden@.........
Date: Sat, 08 Mar 2003 06:03:15 -0500
I did not use reinforcing in the base of my instrument, and I did use a=20
sand mix of concrete. I also let it sit in the mould for a week, and it was=
well over a month before the instrument was complete. I cannot say that I=20
have seen any noise that I can attribute to the use of this construction=20
technique. For the record, my base is about three feet long, 8 inches wide,=
and about 6 inches high. It is shaped like a "U" in cross section to reduce=
weight, and to minimize the cross section thickness. The column is also=20
similarly shaped with the back side hollowed out. The two pieces together=
weight 80 or 90 pounds. It was a real effort to get the assembly off of the=
workbench and down onto the floor.
The instrument lives in a temperature controlled enclosure at about =B10.5=
I consider this necessary to avoid thermal effects particularly because the=
thing is set up in a corner of my garage which, although attached to the=20
house, is not heated.
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