Larry,

I used plain old concrete. Mortar mix works best. Line the mould with 
plastic sheeting for a smooth surface finish, and let it age for a week 
before you try to do anything with it. It worked for me - on the second try.


At 04:27 PM 3/6/03 -0800, you wrote:
>Hi Everyone,
>
>I received this email from Dave Youden regarding a Folded Pendulum
>Seismometer design. Dave is on the PSN-L list. I've placed Dave's Lehman
>photo on my system here http://www.seismicnet.com/photos/lehman1a.jpg and
>his write-up here
>http://www.seismicnet.com/photos/Folded_Pendulum_seismometer.doc. It's in
>Microsoft Word format.
>
>I have one question for Dave. What material was used as a base and support
>for your Lehman sensor?
>
>Regards,
>Larry Cochrane
>Redwood City, PSN
>
>----- Original Message -----
>From: "David H. Youden" 
>To: "Larry Cochrane" 
>Sent: Thursday, March 06, 2003 6:18 AM
>Subject: Folded Pendulum Seismometer
>
>
> > Larry,
> >
> > Please allow me to introduce myself.
> >
> > My name is Dave Youden. I am an applied research engineer employed by
> > Eastman Kodak Company where I work on the design of precision production
> > equipment. I am also a member of the faculty of the Mechanical and
> > Aerospace Engineering Department of North Carolina State University. I
>live
> > in Clayton, NC, a small, but growing community Southeast of Raleigh, NC.
> >
> > I have had a life long interest in earth sciences, and several years ago I
> > built my first seismometer (See photo Lehman.jpg). A year later I built a
> > small S-G instrument the performance of which was disappointing, probably
> > because the 100 mm pendulum was simply too small and was subject to
> > disturbance by air currrents.
> >
> > As a replacement for the S-G instrument I have designed and constructed a
> > folded pendulum instrument which may be of interest to members of the PSN
> > group. Please take a look at the file Folded Pedulum Seismometer.doc and
>if
> > you think that this would be of any interest to the group, you are free to
> > post it if you wish, as I do not have access to a web server.
> >
> > I am a member of the PSN-L mailing list, and I will be more than happy to
> > answer any question that you, or anyone else may have about this
>instrument.
> >
> > The reason that I am sending this to you is that, while web surfing the
> > other day, I ran across John Lahr's web site where I saw a picture of a
> > folded pendulum experiment that he has constructed. I contacted John, and
> > since then have been providing information to a group of students at The
> > Colorado School of Mines, who are trying to design a low-cost seismometer
> > suitable for public school use. Until I contacted John I really had no
>idea
> > that what I have built might be of interest to anyone else.
> >
> > Dave...
> >
> > David H. Youden
> > dyouden@.........
> >
> >
>
>
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