Hi I think that if you are looking at something this size, a compressor based heat / cool setup will do much better than a solid state approach. Way less power due to the much better efficiency . You can get pretty small systems that will hold < 0.05 C on the “coolant line".
Bob > On Sep 10, 2021, at 5:03 PM, Jerome Blaha <jbl...@polariswireless.com> wrote: > > Would the use of a partial vacuum in a sealed chamber or even the septic tank > to reach a somewhat steady-state temperature be out of the question, as only > radiation would dominate the temperature? > > Bill's idea of a 0C water bath also sounds kind of cool and perhaps it might > be attainable with a double or triple stacked pettier cooler (reversible in > voltage if your outdoor temps get below 0C) with very small tubing with > coolant and two tiny DC powered pumps for redundancy with check valves to a > small radiator inside the crypt water/ice bath with an RTD temperature > sensor. Throw in an above-ground solar and battery backup, and the > solid-state refrigeration unit could be fully self-contained and located far > enough from the time crypt to not influence gravity, magnetism, quantum > physics, etc. > > -Jerome Blaha Jr > > > > -----Original Message----- > From: time-nuts-requ...@lists.febo.com > [mailto:time-nuts-requ...@lists.febo.com] > Sent: Friday, September 10, 2021 12:30 AM > To: time-nuts@lists.febo.com > Subject: time-nuts Digest, Vol 209, Issue 7 > > Send time-nuts mailing list submissions to > time-nuts@lists.febo.com > > To subscribe or unsubscribe via email, send a message with subject or > body 'help' to > time-nuts-requ...@lists.febo.com > > You can reach the person managing the list at > time-nuts-ow...@lists.febo.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > Today's Topics: > > 1. Re: in-ground clock room (B Riches) > 2. Re: in-ground clock room (Dana Whitlow) > 3. Re: in-ground clock room (Andy Gardner, ZL3AG) > 4. Re: in-ground clock room (Dana Whitlow) > 5. Re: in-ground clock room (Bob kb8tq) > 6. Re: in-ground clock room (Brent) > 7. Re: in-ground clock room (Joseph Gwinn) > 8. Re: in-ground clock room (Steve Allen) > 9. Re: in-ground clock room (Scott McGrath) > 10. Re: in-ground clock room (Dana Whitlow) > 11. Re: in-ground clock room (Gilles Clement) > 12. Re: in-ground clock room (John Marvin) > 13. Re: [time nuts] Re: in-ground clock room (Bill Beam) > 14. Re: in-ground clock room (Lux, Jim) > 15. Re: in-ground clock room (Graham / KE9H) > 16. Re: in-ground clock room (Ben Bradley) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 9 Sep 2021 11:17:02 +0000 (UTC) > From: B Riches <bill.ric...@verizon.net> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com>, Tom Van Baak <t...@leapsecond.com> > Message-ID: <376021411.3362644.1631186222...@mail.yahoo.com> > Content-Type: text/plain; charset=UTF-8 > > How about using a round septic tank. Mine is about 5 feet wide and 6 feet > deep Large hole in the top - put ladder for entry. > 73, > Bill, WA2DVUCape May, NJ > On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam <wb...@gci.net> > wrote: > > On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote: > >> On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote: > >>> 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 (t...@leapsecond.com). > >>> Thanks, >>> /tvb > >> Tom, > >> How long do you expect your proposed voult to go undisturbed? >> I have several pendulum clocks. They are disturbed every couple of months >> by earth quakes. By disturbed, I mean pendulum banging against the case >> walls.... >> Any ground motion that can be felt will upset the clocks. Often the clocks >> will >> signal an earth quake that is not felt. > >> Good luck. > > I spent a few years as a geotechnic/soils engineer and learned as others have > pointed out > that a thermal wave of period one year and wave length of several meters > propagates > downward thru the soil. Peak amplitude of a few degrees can be expected near > the surface. > > Consider building an "oven" with the clock vault freely floating in a > water-ice mixture. This will > provide constant temperature (0C) and limited mechanical isolation from earth > quakes. > > But of course this will be expensive to operate. > > As you know 'good' clocks require a lot of energy and generate a lot of > entropy. > > Protecting the quartz oscillators is much easier than protecting the pendulum > clocks. > > > > > Bill Beam > NL7F > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 2 > Date: Thu, 9 Sep 2021 07:09:33 -0500 > From: Dana Whitlow <k8yumdoo...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: > <cadhrwpfdjccbgnwncxsssngipix9nfckxd5f3hjjs3eivaq...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > It seems to me that in order to derive much thermal stabilization, the *top* > of the space would need to be several feet underground (depending on > geographic location). And I think that the means for human access would > likely "spoil the broth" unless fairly extreme measures were taken. > > Wouldn't it be sufficient to use a space whose thermal coupling were weak > enough to make the time constant a few days (instead of months)? Then, > ordinary inexpensive means like GPS-locked Rb standards with suitable > (longish) time constants should clean up "GPS noise", yet enable the loop > to take care of low rate temperature variations in the protected space due > to outside temperature changes. > > Remember, perfection in clocks is expensive- according to recent things I've > read about entropy of timekeeping, a perfect clock would require infinite > power, > and that alone would blow away all one's efforts at temperature control. > > Dana > > > On Thu, Sep 9, 2021 at 6:19 AM B Riches via time-nuts < > time-nuts@lists.febo.com> wrote: > >> How about using a round septic tank. Mine is about 5 feet wide and 6 >> feet deep Large hole in the top - put ladder for entry. >> 73, >> Bill, WA2DVUCape May, NJ >> On Thursday, September 9, 2021, 02:29:40 AM EDT, Bill Beam < >> wb...@gci.net> wrote: >> >> On Wed, 08 Sep 2021 18:36:11 -0800, Bill Beam wrote: >> >>> On Wed, 8 Sep 2021 18:54:03 -0700, Tom Van Baak wrote: >> >>>> 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 (t...@leapsecond.com). >> >>>> Thanks, >>>> /tvb >> >>> Tom, >> >>> How long do you expect your proposed voult to go undisturbed? >>> I have several pendulum clocks. They are disturbed every couple of months >>> by earth quakes. By disturbed, I mean pendulum banging against the case >> walls.... >>> Any ground motion that can be felt will upset the clocks. Often the >> clocks will >>> signal an earth quake that is not felt. >> >>> Good luck. >> >> I spent a few years as a geotechnic/soils engineer and learned as others >> have pointed out >> that a thermal wave of period one year and wave length of several meters >> propagates >> downward thru the soil. Peak amplitude of a few degrees can be expected >> near the surface. >> >> Consider building an "oven" with the clock vault freely floating in a >> water-ice mixture. This will >> provide constant temperature (0C) and limited mechanical isolation from >> earth quakes. >> >> But of course this will be expensive to operate. >> >> As you know 'good' clocks require a lot of energy and generate a lot of >> entropy. >> >> Protecting the quartz oscillators is much easier than protecting the >> pendulum clocks. >> >> >> >> >> Bill Beam >> NL7F >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 3 > Date: Fri, 10 Sep 2021 00:29:15 +1200 > From: "Andy Gardner, ZL3AG" <zl...@radioengineering.com> > Subject: [time-nuts] Re: in-ground clock room > To: time-nuts@lists.febo.com > Message-ID: > <0615ccea-ea7e-a4e3-7c19-8767c37d2...@radioengineering.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > > > So the 2 things you're after are thermal insulation and vibration insulation? > > Digging can be expensive, and you have to worry about water table in many > locations. > > How about the thickest concrete water tank you can find, plonk it in a nice > location, spray layers of polyurethane foam over the top and sides for > thermal insulation, then build a wind shield ("shed") around it. The shed > could be an old coolstore, adding more insulation. > > Concrete water tanks are out of fashion these days due to plastics, so if you > shop around you can find a cheap used one, and then it's just the > trucking/crane charges. > > > > ------------------------------ > > Message: 4 > Date: Thu, 9 Sep 2021 07:38:30 -0500 > From: Dana Whitlow <k8yumdoo...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: > <CADHrwpdUZSteVrKK_PKfbsCYcJX311TAj7=tbq7nayofopu...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Tom, > > Andy brings up good points, especially about water leaks. > Are you familiar with "Whitlow's 5th law" (which can be summarized > as "everything leaks")? > > Dana Whitlow > > > On Thu, Sep 9, 2021 at 7:29 AM Andy Gardner, ZL3AG via time-nuts < > time-nuts@lists.febo.com> wrote: > >> >> >> So the 2 things you're after are thermal insulation and vibration >> insulation? >> >> Digging can be expensive, and you have to worry about water table in many >> locations. >> >> How about the thickest concrete water tank you can find, plonk it in a >> nice location, spray layers of polyurethane foam over the top and sides for >> thermal insulation, then build a wind shield ("shed") around it. The shed >> could be an old coolstore, adding more insulation. >> >> Concrete water tanks are out of fashion these days due to plastics, so if >> you shop around you can find a cheap used one, and then it's just the >> trucking/crane charges. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. >> > > ------------------------------ > > Message: 5 > Date: Thu, 9 Sep 2021 09:04:04 -0400 > From: Bob kb8tq <kb...@n1k.org> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Cc: Tom Van Baak <t...@leapsecond.com> > Message-ID: <e624e63e-7bcd-49e8-9af5-ff9c7c32e...@n1k.org> > Content-Type: text/plain; charset=utf-8 > > Hi > > You could do some research on the climate in various parts of the world. > Pick the ideal location and move there :) :) You also could optimize the > location for various tidal forces …. > > How deep can you go on your property before you run into something > massive? Around here, I can go down between a foot and maybe two > feet. At that point it’s time for dynamite. You do not ask “how much to > put in a swimming pool?” in this neighborhood. Part of this is the geology, > part is how the builder graded things to put in the subdivision. > > While that *sounds* ideal, the shale is tilted due to some thing running into > something else a while ago. The net result is ground water running here > and there to some fairly significant depths. As the seasons change that > ground water and its somewhat random route changes isn’t ideal for > temperature stability. > > Yes, it’s all about some *very* local aspects of your geology. With some > care, I could move a few miles in one direction or another and be in a *very* > different situation. (again thanks to just how this ran into that ….). > > Since temperature stability is only part of the design and mechanical > stability is the other. This location might work ok for half of the design > goals …. Granite likely would do better than fractured shale though ... > > Bob > >> On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote: >> >> -------- >> Tom Van Baak writes: >> >>> 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. >> >> I researched this extensively before we built a house 5 years ago. >> >> Look at the plot on page 37 in this paper: >> >> >> https://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~ >> >> It shows that in Denmark the yearly temperature variations in >> penetrates to a depth of 15 meters, and that even at 10 meters >> depth, you can expect the swing to be several Kelvin in any year. >> >> I did find handwaving which said tree-cover reduced the swing by >> "a lot" but no measurements to substantiate it. >> >> In the end I concluded that I could do better in the comfort of my lab. >> >> You should try to find similar data for your local climate and >> geology, before you pour too much money into a hole in the ground. >> >> -- >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >> p...@freebsd.org | TCP/IP since RFC 956 >> FreeBSD committer | BSD since 4.3-tahoe >> Never attribute to malice what can adequately be explained by incompetence. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 6 > Date: Thu, 9 Sep 2021 10:12:06 -0400 > From: Brent <brent.ev...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: > <CAP6i9Mni5LDGDaanNB5QP=shtyerlqurbknu7ivo6chaxas...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Seismic vaults are built similar to your requirements. I suggest looking > up the Earthscope program - there should be info out on the web as to how > their vaults were designed, but in a nutshell, dig a hole, put some gravel > in the bottom, place a large culvert on end in the hole, pour a few inches > of concrete in the culvert, put instrumentation in a pedestal inside, run > power and comms, put a bilge pump and outflow pipe in it on the floor > (below pedastal), and put a cap on the whole thing. Those were then > re-buried, but that prevents easy access (although it probably improves > temperature stability). A septic tank would be larger, but more effort, and > may expose more surface area to the sun (temp variation). > > I've been in various seismic vaults and they can vary from very extravagant > to downright crude. > > > > On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq <kb...@n1k.org> wrote: > >> Hi >> >> You could do some research on the climate in various parts of the world. >> Pick the ideal location and move there :) :) You also could optimize the >> location for various tidal forces …. >> >> How deep can you go on your property before you run into something >> massive? Around here, I can go down between a foot and maybe two >> feet. At that point it’s time for dynamite. You do not ask “how much to >> put in a swimming pool?” in this neighborhood. Part of this is the >> geology, >> part is how the builder graded things to put in the subdivision. >> >> While that *sounds* ideal, the shale is tilted due to some thing running >> into >> something else a while ago. The net result is ground water running here >> and there to some fairly significant depths. As the seasons change that >> ground water and its somewhat random route changes isn’t ideal for >> temperature stability. >> >> Yes, it’s all about some *very* local aspects of your geology. With some >> care, I could move a few miles in one direction or another and be in a >> *very* >> different situation. (again thanks to just how this ran into that ….). >> >> Since temperature stability is only part of the design and mechanical >> stability is the other. This location might work ok for half of the design >> goals …. Granite likely would do better than fractured shale though ... >> >> Bob >> >>> On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> >> wrote: >>> >>> -------- >>> Tom Van Baak writes: >>> >>>> 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. >>> >>> I researched this extensively before we built a house 5 years ago. >>> >>> Look at the plot on page 37 in this paper: >>> >>> >> https://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~ >>> >>> It shows that in Denmark the yearly temperature variations in >>> penetrates to a depth of 15 meters, and that even at 10 meters >>> depth, you can expect the swing to be several Kelvin in any year. >>> >>> I did find handwaving which said tree-cover reduced the swing by >>> "a lot" but no measurements to substantiate it. >>> >>> In the end I concluded that I could do better in the comfort of my lab. >>> >>> You should try to find similar data for your local climate and >>> geology, before you pour too much money into a hole in the ground. >>> >>> -- >>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >>> p...@freebsd.org | TCP/IP since RFC 956 >>> FreeBSD committer | BSD since 4.3-tahoe >>> Never attribute to malice what can adequately be explained by >> incompetence. >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 7 > Date: Thu, 9 Sep 2021 12:02:44 -0400 > From: Joseph Gwinn <joegw...@comcast.net> > Subject: [time-nuts] Re: in-ground clock room > To: time-nuts@lists.febo.com > Message-ID: <20210909120244341063.4dfa1...@comcast.net> > Content-Type: text/plain; charset=iso-8859-1 > > On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-requ...@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 <t...@leapsecond.com> >> Subject: [time-nuts] in-ground clock room >> To: Discussion of precise time and frequency measurement >> <time-nuts@lists.febo.com> >> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf19327...@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 (t...@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 > > ------------------------------ > > Message: 8 > Date: Thu, 9 Sep 2021 09:13:18 -0700 > From: Steve Allen <s...@ucolick.org> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: <20210909161318.ga19...@ucolick.org> > Content-Type: text/plain; charset=utf-8 > > On Wed 2021-09-08T18:54:03-0700 Tom Van Baak hath writ: >> 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. > > How deep? > > Bulletin Horaire v3n46p262 (1929-02-10) reports the equipment, > facilities, and operations of Bureau International de l'Heure at > Observatoire de Paris. > > The highest precision pendulum clocks, the ones which had mechanisms > to correct for temperature and pressure (the "garde-temps") were kept > 27 m below ground in caves and galleries which were part of the > Paris catacombs. > > Various issues of Bulletin Horaire report discontinuities in the > operation of those clocks due to distant earthquakes. > > -- > Steve Allen <s...@ucolick.org> WGS-84 (GPS) > UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 > 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 > Santa Cruz, CA 95064 > https://url.emailprotection.link/?babImg0bEUxMHpPsxOmCp3Cn-KMvw54w86vJHHj3bTiz-n20wRlflI_23_p5IjE256VI1iFbNSdl2v6Rv0dqwQw~~ > Hgt +250 m > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------ > > Message: 9 > Date: Thu, 9 Sep 2021 12:28:00 -0400 > From: Scott McGrath <scmcgr...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: <0595152c-c512-45d9-8903-f2616d349...@gmail.com> > Content-Type: text/plain; charset=utf-8 > > > 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 <joegw...@comcast.net> wrote: > > On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-requ...@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 <t...@leapsecond.com> >> Subject: [time-nuts] in-ground clock room >> To: Discussion of precise time and frequency measurement >> <time-nuts@lists.febo.com> >> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf19327...@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 (t...@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 > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 10 > Date: Thu, 9 Sep 2021 11:35:30 -0500 > From: Dana Whitlow <k8yumdoo...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: > <cadhrwpffwgtpax+s02yfnex704rp_5rwgxheffjab+alf8i...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > One might also consider mounting smaller items inside the cylinders of the > engine block, > to get the most out of its thermal mass. > > Dana > > > On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn <joegw...@comcast.net> wrote: > >> On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-requ...@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 <t...@leapsecond.com> >>> Subject: [time-nuts] in-ground clock room >>> To: Discussion of precise time and frequency measurement >>> <time-nuts@lists.febo.com> >>> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf19327...@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 (t...@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 >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. >> > > ------------------------------ > > Message: 11 > Date: Thu, 9 Sep 2021 21:05:11 +0200 > From: Gilles Clement <clemg...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: <c3b65d1e-3eb2-42f0-8291-46eba92dd...@gmail.com> > Content-Type: text/plain; charset=utf-8 > > With a slight cantilevered cavity at the base, > instrumental as a *nut cracker… o:)) > * = time? > >> Le 9 sept. 2021 à 18:35, Dana Whitlow <k8yumdoo...@gmail.com> a écrit : >> >> One might also consider mounting smaller items inside the cylinders of the >> engine block, >> to get the most out of its thermal mass. >> >> Dana >> >> >> On Thu, Sep 9, 2021 at 11:03 AM Joseph Gwinn <joegw...@comcast.net> wrote: >> >>> On Thu, 09 Sep 2021 03:30:35 -0400, time-nuts-requ...@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 <t...@leapsecond.com> >>>> Subject: [time-nuts] in-ground clock room >>>> To: Discussion of precise time and frequency measurement >>>> <time-nuts@lists.febo.com> >>>> Message-ID: <4037f6cb-ade3-8c01-8c36-7edf19327...@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 (t...@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 >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >>> an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >>> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 12 > Date: Thu, 9 Sep 2021 13:57:44 -0600 > From: John Marvin <jm-t...@themarvins.org> > Subject: [time-nuts] Re: in-ground clock room > To: time-nuts@lists.febo.com > Message-ID: <7c02f7ff-8cd7-e2b2-88af-16f6ee138...@themarvins.org> > Content-Type: text/plain; charset=utf-8; format=flowed > > Hmm, this list isn't called time-science, time-research, time-hardware, > or time-trivia. It's called time-nuts. This is probably one of the most > on topic (and fun) posts I've seen on this list. :) > > Regards, > > John > > On 9/8/2021 7:54 PM, Tom Van Baak wrote: >> >> In case this gets too off-topic for time-nuts, off-list email to me is >> fine (t...@leapsecond.com). >> >> Thanks, >> /tvb >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > > ------------------------------ > > Message: 13 > Date: Thu, 09 Sep 2021 13:57:30 -0800 > From: "Bill Beam" <wb...@gci.net> > Subject: [time-nuts] Re: [time nuts] Re: in-ground clock room > To: "Discussion of precise time and frequency measurement" > <time-nuts@lists.febo.com> > Message-ID: <05.1f.05200.1538a...@smtp02.beryl.bos.sync.lan> > Content-Type: text/plain; charset="us-ascii" > > --Original Message Text--- > From: Tom Van Baak > Date: Thu, 9 Sep 2021 04:44:22 -0700 > > > > Hi Bill, > > I'd like undisturbed on the order of several months or years. Yes, > earthquakes are possible but they are rare here and interesting so that's > ok. Here's a once-in-a-decade one that I captured a few years ago: > > https://url.emailprotection.link/?bdmFbtBVI5fRq-9wNeYkQ-gFamK1O8vBt3YAwjEUQaSUMHPHLx-i6bKvykxCz-00ThdyGMxzxk6o8IrmSaUTCxvJs0WcGPc8YKQXXSuyy8vAq8OBpMvaoBVHqIvOyCFuf > > > The main thing is to avoid "cultural noise" -- local seismic activity caused > by cars, trucks, doors opening and closing, people walking, A/C or > mechanical appliances going on and off, etc. This is best done by locating > the clocks away from roads, away from the house, in a solid > compartment weighing many tons, underground in virgin soil or bedrock. > > Hi Tom, > > A "compartment weighing many tons" is a low pass filter good against > "cultural noise" but not so good against earth quake or earth tide > noise. A "compartment weighing many tons" is strongly coupled to the earth. > The opposite approach is to uncouple from the earth as > much as possible. Your earthquake enviornment in the Pacific northwest is > similar to here in Alaska. Your precision pendulum clock > is good enough to respond to monthly/daily earth tides. There is a 'catch 22' > in trying to protect a pendulum clock. The pendulum > depends on constant acceleration of gravity. It ain't constant. If g varies > or is noisy by one part in N then that sets the point of diminishing > return in your protection efforts. > > Bill > > /tvb > On 9/8/2021 7:36 PM, Bill Beam wrote: > > Tom, > > How long do you expect your proposed voult to go undisturbed? > I have several pendulum clocks. They are disturbed every couple of months > by earth quakes. By disturbed, I mean pendulum banging against the case > walls.... > Any ground motion that can be felt will upset the clocks. Often the clocks > will > signal an earth quake that is not felt. > > Good luck. > > > > > Bill Beam > NL7F > > > > > Bill Beam > NL7F > > > > ------------------------------ > > Message: 14 > Date: Thu, 9 Sep 2021 15:17:22 -0700 > From: "Lux, Jim" <j...@luxfamily.com> > Subject: [time-nuts] Re: in-ground clock room > To: time-nuts@lists.febo.com > Message-ID: <dbb895a4-371c-81bb-2ae0-7a9822746...@luxfamily.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > On 9/8/21 6:54 PM, Tom Van Baak wrote: >> 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. >> > A few years back, we were looking at building a "test rubble pile" for > search and rescue applications (actually for testing equipment that > would be used for this). > > For the depths you're talking about (few meters) the easiest approach is > to get someone with a backhoe to dig a pit, then use the backhoe to > carry the precast vault, drop it in, and you're done. If you were going > more than "backhoe depth" you're looking at something like an auger, and > they can drill any diameter (up to about 4 feet) and any depth, as long > as they can get the truck into position (same as the backhoe). > > I went around looking at the precast concrete vendors - they're > available in any size you want. You can also just sink a drain pipe of > any size vertically, and fill the bottom with concrete. The vaults often > come with "knockouts" - places where you can bring conduit in by > knocking out the plug of concrete (it's cast with a thin ring, so you > hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault > seal is done with a variety of goops. Some of the ones I've seen look > like tar (the same stuff used to fix roads, roofs, shower pans), others > use some sort of foam. > > The prices for this stuff are fairly standardized - your local utility > or roads department probably has a "standard bid list" for most of the > more common items that they use for doing estimates. Caltrans certainly > does (a 48" precast concrete manhole is about $1500). So that gives you > a ballpark when you start calling vendors. The big driver for most > people in a "residential" environment would be access. It's one thing > to have a double flatbed show up with a bunch of concrete pipe on it at > a business, totally another on a winding residential street. We had > stuff delivered on a flatbed truck with a small crane - but they could > just pull up to the site, sling the vault, and lower it to the ground, > and then the backhoe guy moved it. Going up a driveway, around the > corner, avoiding the fence, etc. would be different. Or, A *really big* > crane - I've seen that done - 80 or 100 foot boom in the street - they > pick the load up, lift it up and over the house and place it in the back > yard. > > https://url.emailprotection.link/?b4vU3x8i5fTvyzlQz6y9GOCtVn2tdfzrFSR54T5cRl_uAtXpIOtBBqqwnV4vvFy1BmFE0feOJrmWRAW6qHW8lkO6-L7cdYeUDZSpmMaEHfuxRGyelFEjAK6MatgClTQ9f > > https://url.emailprotection.link/?bMgheXmXOXXWGkEGh8fPBr6lrAr7Q86Lv2pzXVXq2h2r6_ZhJY1XlJ6RJXJzCSe7od5P0dH6_AGbo4tSHU_9d3dnFyDDiNcXCASM95efa7VWFoeLurCDQb4g3_4LRgWkW > > https://url.emailprotection.link/?bVk3-XAtcEXlrmrcOdaAPyyNHDetyE--dojTOGrR3Q1jmKx0N586lNzcUPLMddNAV7AFKoc4NMWmZVMAgYIkuvHw_TAaIGWVfhJ4hoixRP-POCndpSfmCsbHIJwmgK3qa > > Google "precast concrete manhole" and select accordingly. > > > > You're looking at the "more than $1000 probably less than $10k" range, > all done in a day, plus a day of prep and a day of cleanup. > > Backhoes (in SoCal) are going for $300-500/day plus the operator > ($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as > a rookie, but digging a hole is pretty easy to learn on your own. And I > just looked it up, the smaller skid-steer bobcat type could probably dig > a 2 meter deep hole, and you're less likely to do major damage like you > can with a full sized unit. > > Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day , > $1005/week > > https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~ > You might find someone who's usually doing stuff like pools and spas, > and will dig your hole for you. In any case, probably not more than $1000 > > > One other source for design is "storm shelters" - FEMA has published > pre-engineered designs for a variety of inground shelters (often, > installed below a garage) > > > One final thing - even if it's waterproofed, it *will collect water* > either by condensation or seepage. You might need to make your clock > vault have some sort of dehumidifier and/or sump pump. > > > The other alternative is to "build a basement" - dig the hole by hand, > pour a slab, and either pour walls or stack blocks and pour into the > cavities. 1x1x2 meters is sort of doable.. figure standard 8x16" > blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft. > That's big enough to stand in, but there is a significant cave-in > hazard, If you're down 2 meters, and the side collapses on you, you'll > probably die before they can dig you out. Or, your soil is sturdy > enough, you manage the risk. > I don't think you could dig 2 meters down with one of those small bobcat > backhoes or excavators, you'd have to dig a ramp, stack your blocks, > then backfill. > > >> In case this gets too off-topic for time-nuts, off-list email to me is >> fine (t...@leapsecond.com). >> >> Thanks, >> /tvb >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. >> > > ------------------------------ > > Message: 15 > Date: Thu, 9 Sep 2021 18:03:08 -0500 > From: "Graham / KE9H" <ke9h.gra...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: > <CAPyJ-YWhz_C7r=mej91skkmeqtba7rrxvkzatbyca3carqo...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Sounds like we need a volunteer time-nut with motion picture camera > capability to document this event. > --- Graham > > On Thu, Sep 9, 2021 at 5:17 PM Lux, Jim <j...@luxfamily.com> wrote: > >> On 9/8/21 6:54 PM, Tom Van Baak wrote: >>> 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. >>> >> A few years back, we were looking at building a "test rubble pile" for >> search and rescue applications (actually for testing equipment that >> would be used for this). >> >> For the depths you're talking about (few meters) the easiest approach is >> to get someone with a backhoe to dig a pit, then use the backhoe to >> carry the precast vault, drop it in, and you're done. If you were going >> more than "backhoe depth" you're looking at something like an auger, and >> they can drill any diameter (up to about 4 feet) and any depth, as long >> as they can get the truck into position (same as the backhoe). >> >> I went around looking at the precast concrete vendors - they're >> available in any size you want. You can also just sink a drain pipe of >> any size vertically, and fill the bottom with concrete. The vaults often >> come with "knockouts" - places where you can bring conduit in by >> knocking out the plug of concrete (it's cast with a thin ring, so you >> hit it with a sledge) - the conduit (or duct, or sewer pipe) to vault >> seal is done with a variety of goops. Some of the ones I've seen look >> like tar (the same stuff used to fix roads, roofs, shower pans), others >> use some sort of foam. >> >> The prices for this stuff are fairly standardized - your local utility >> or roads department probably has a "standard bid list" for most of the >> more common items that they use for doing estimates. Caltrans certainly >> does (a 48" precast concrete manhole is about $1500). So that gives you >> a ballpark when you start calling vendors. The big driver for most >> people in a "residential" environment would be access. It's one thing >> to have a double flatbed show up with a bunch of concrete pipe on it at >> a business, totally another on a winding residential street. We had >> stuff delivered on a flatbed truck with a small crane - but they could >> just pull up to the site, sling the vault, and lower it to the ground, >> and then the backhoe guy moved it. Going up a driveway, around the >> corner, avoiding the fence, etc. would be different. Or, A *really big* >> crane - I've seen that done - 80 or 100 foot boom in the street - they >> pick the load up, lift it up and over the house and place it in the back >> yard. >> >> https://url.emailprotection.link/?b4vU3x8i5fTvyzlQz6y9GOCtVn2tdfzrFSR54T5cRl_uAtXpIOtBBqqwnV4vvFy1BmFE0feOJrmWRAW6qHW8lkO6-L7cdYeUDZSpmMaEHfuxRGyelFEjAK6MatgClTQ9f >> >> https://url.emailprotection.link/?bMgheXmXOXXWGkEGh8fPBr6lrAr7Q86Lv2pzXVXq2h2r6_ZhJY1XlJ6RJXJzCSe7od5P0dH6_AGbo4tSHU_9d3dnFyDDiNcXCASM95efa7VWFoeLurCDQb4g3_4LRgWkW >> >> https://url.emailprotection.link/?bVk3-XAtcEXlrmrcOdaAPyyNHDetyE--dojTOGrR3Q1jmKx0N586lNzcUPLMddNAV7AFKoc4NMWmZVMAgYIkuvHw_TAaIGWVfhJ4hoixRP-POCndpSfmCsbHIJwmgK3qa >> >> Google "precast concrete manhole" and select accordingly. >> >> >> >> You're looking at the "more than $1000 probably less than $10k" range, >> all done in a day, plus a day of prep and a day of cleanup. >> >> Backhoes (in SoCal) are going for $300-500/day plus the operator >> ($50-60/hr).. Or you can learn <grin> - it's hard to do precise work as >> a rookie, but digging a hole is pretty easy to learn on your own. And I >> just looked it up, the smaller skid-steer bobcat type could probably dig >> a 2 meter deep hole, and you're less likely to do major damage like you >> can with a full sized unit. >> >> Home Depot actually rents them.. 2-3 ton miniexcavator is $359/day , >> $1005/week >> >> >> https://url.emailprotection.link/?bxi_ZidtnD6xI2zzRsDcyqHffqrVSTox2oC_9uR1Wn__cx-QkF7-Kv6g3eSHSQXVRCEScpWUjnFhYyGMh7sNJsLTX7jEpYYFUeXU-3m8m5VxPLSAdykYV5m7GHxP5C7EKwkjeioOHRo2PxK0hM71HEHd0OMGm7kPpMvrEMyYWd90~ >> You might find someone who's usually doing stuff like pools and spas, >> and will dig your hole for you. In any case, probably not more than $1000 >> >> >> One other source for design is "storm shelters" - FEMA has published >> pre-engineered designs for a variety of inground shelters (often, >> installed below a garage) >> >> >> One final thing - even if it's waterproofed, it *will collect water* >> either by condensation or seepage. You might need to make your clock >> vault have some sort of dehumidifier and/or sump pump. >> >> >> The other alternative is to "build a basement" - dig the hole by hand, >> pour a slab, and either pour walls or stack blocks and pour into the >> cavities. 1x1x2 meters is sort of doable.. figure standard 8x16" >> blocks, so the "hole" is going to be 16+39=55" square - figure 5 ft. >> That's big enough to stand in, but there is a significant cave-in >> hazard, If you're down 2 meters, and the side collapses on you, you'll >> probably die before they can dig you out. Or, your soil is sturdy >> enough, you manage the risk. >> I don't think you could dig 2 meters down with one of those small bobcat >> backhoes or excavators, you'd have to dig a ramp, stack your blocks, >> then backfill. >> >> >>> In case this gets too off-topic for time-nuts, off-list email to me is >>> fine (t...@leapsecond.com). >>> >>> Thanks, >>> /tvb >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >>> send an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >>> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >> an email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Message: 16 > Date: Thu, 9 Sep 2021 20:47:29 -0400 > From: Ben Bradley <ben.pi.brad...@gmail.com> > Subject: [time-nuts] Re: in-ground clock room > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Message-ID: > <CA+wjhVsKT67AOghjXT91LwupF0FG3v=xiqex4q0-2jvrqyh...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > I've seen discussion of making a seismic vault (though not sure if > they used that name, making it harder to find in the haystack of > posts) on this mailing list, maybt 15 or 20 years ago, so nut sure if > this is helpful: > https://url.emailprotection.link/?bj4D6X82wPC9xeltcsFCTXzK_O0xDS6ilwrNrr973O-CWyDkiYmR6AtIlije3Uhl-EhDjaWB722xAQMGo5pYzKsypwE_cPrdr7cPkFE8GrFQ48neYZCy5Hu7yuZjpSqlB > > For possible immunity from earthquakes, LIGO uses some quite complex > control and feedback systems to hang its mirrors so that mild > earthquakes and local noise won't affect them. From what I've seen > over the years a lot of this info has been published, but I imagine it > would be quite expensive to reproduce. Maybe some sort of Ligo Lite > system would be feasible. > > On Thu, Sep 9, 2021 at 10:13 AM Brent <brent.ev...@gmail.com> wrote: >> >> Seismic vaults are built similar to your requirements. I suggest looking >> up the Earthscope program - there should be info out on the web as to how >> their vaults were designed, but in a nutshell, dig a hole, put some gravel >> in the bottom, place a large culvert on end in the hole, pour a few inches >> of concrete in the culvert, put instrumentation in a pedestal inside, run >> power and comms, put a bilge pump and outflow pipe in it on the floor >> (below pedastal), and put a cap on the whole thing. Those were then >> re-buried, but that prevents easy access (although it probably improves >> temperature stability). A septic tank would be larger, but more effort, and >> may expose more surface area to the sun (temp variation). >> >> I've been in various seismic vaults and they can vary from very extravagant >> to downright crude. >> >> >> >> On Thu, Sep 9, 2021 at 9:04 AM Bob kb8tq <kb...@n1k.org> wrote: >> >>> Hi >>> >>> You could do some research on the climate in various parts of the world. >>> Pick the ideal location and move there :) :) You also could optimize the >>> location for various tidal forces …. >>> >>> How deep can you go on your property before you run into something >>> massive? Around here, I can go down between a foot and maybe two >>> feet. At that point it’s time for dynamite. You do not ask “how much to >>> put in a swimming pool?” in this neighborhood. Part of this is the >>> geology, >>> part is how the builder graded things to put in the subdivision. >>> >>> While that *sounds* ideal, the shale is tilted due to some thing running >>> into >>> something else a while ago. The net result is ground water running here >>> and there to some fairly significant depths. As the seasons change that >>> ground water and its somewhat random route changes isn’t ideal for >>> temperature stability. >>> >>> Yes, it’s all about some *very* local aspects of your geology. With some >>> care, I could move a few miles in one direction or another and be in a >>> *very* >>> different situation. (again thanks to just how this ran into that ….). >>> >>> Since temperature stability is only part of the design and mechanical >>> stability is the other. This location might work ok for half of the design >>> goals …. Granite likely would do better than fractured shale though ... >>> >>> Bob >>> >>>> On Sep 9, 2021, at 1:20 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> >>> wrote: >>>> >>>> -------- >>>> Tom Van Baak writes: >>>> >>>>> 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. >>>> >>>> I researched this extensively before we built a house 5 years ago. >>>> >>>> Look at the plot on page 37 in this paper: >>>> >>>> >>> https://url.emailprotection.link/?bUQcqOjURXhTPB6JfDc92MEONol3xTSgYvfeJ8BbiBWRjdyPVNx0zkKcKHTkrvxHEUgotv-qebTvJWhqYNQ7vZ5PmnBkg4k4h3etdOL-lB35s4BUytlJhLgWSYHxkU2mT3qsp3DRrx7JvchbPB-BTzWEvV1ZErfgyCy4iwT8fE2oN0ulm9DaMsjEqQThbX3q7ylNve8Qz8EIqdBClbB4zPA~~ >>>> >>>> It shows that in Denmark the yearly temperature variations in >>>> penetrates to a depth of 15 meters, and that even at 10 meters >>>> depth, you can expect the swing to be several Kelvin in any year. >>>> >>>> I did find handwaving which said tree-cover reduced the swing by >>>> "a lot" but no measurements to substantiate it. >>>> >>>> In the end I concluded that I could do better in the comfort of my lab. >>>> >>>> You should try to find similar data for your local climate and >>>> geology, before you pour too much money into a hole in the ground. >>>> >>>> -- >>>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >>>> p...@freebsd.org | TCP/IP since RFC 956 >>>> FreeBSD committer | BSD since 4.3-tahoe >>>> Never attribute to malice what can adequately be explained by >>> incompetence. >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >>> send an email to time-nuts-le...@lists.febo.com >>>> To unsubscribe, go to and follow the instructions there. >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send >>> an email to time-nuts-le...@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >> email to time-nuts-le...@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-le...@lists.febo.com > %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s > > ------------------------------ > > End of time-nuts Digest, Vol 209, Issue 7 > ***************************************** > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
