[time-nuts] Re: in-ground clock room

[Joseph Gwinn]

On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-request at lists.febo.com 
wrote:
Re: time-nuts Digest, Vol 209, Issue 6


> ------------------------------
> > Date: Wed, 8 Sep 2021 18:54:03 -0700
> From: Tom Van Baak <tvb at LeapSecond.com>
> Subject: [time-nuts] in-ground clock room
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at lists.febo.com>
> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf193274d6 at LeapSecond.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> I am considering a below ground "clock room" away from the house. This 
> will be for some low-drift quartz oscillators and also a couple of 
> precision pendulum clocks. The goal is long-term, unattended, and very 
> undisturbed operation.
> 
> For scale, assume the room is 1 meter × 1 meter × 2 meters deep. So 
> that's vastly smaller than digging a basement, but much larger than 
> drilling a 8 inch round pipe. Digging down gives some natural isolation 
> and temperature regulation. A couple tons of concrete gives high 
> stability vertical walls for the pendulum clocks.
> 
> If any of you have personal or professional experience with the design 
> or construction of this sort of thing, especially experience with 
> precast (utility) vaults or poured concrete, please let me know.
> 
> In case this gets too off-topic for time-nuts, off-list email to me is 
> fine (tvb at leapsecond.com).

As others have said, it may not be economically practical to build an 
underground clock room.

Assuming that you have a basement of other suitable room in your 
house, I'd suggest an insulated box or room containing a big lump of 
iron riding on an inner-tube suspension of some kind.   The big lump 
of iron can be a 500-pound truck engine head or block from a 
junkyard, steam cleaned (to remove oil) and painted (to keep the rust 
under control).  Drill and tap holes as needed for mounting.

This box/room plus block can be set up as a temperature-controlled 
oven with a few extra components, including a PID controller.

Bolt a thick plywood floor to the top of the iron hunk, and attach 
the clocks to this floor.

Joe Gwinn