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

[Scott McGrath]

Rather than custom casting a structure you might want to consider use of a precast concrete septic tank or transformer vault as cost will be much lower.

You will also need to consider waterproofing the tank it already has a layer of waterproofing but a couple of additional layers will probably be necessary as well as ensuring proper drainage around it as it will need to be both above local water table and be able to drain off percolating rainwater. 

You will also need to control temperature and humidity 

On Sep 9, 2021, at 12:03 PM, Joseph Gwinn <joegwinn at comcast.net> wrote:

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
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