Hi Ted
To me the important thing is that the upper hinge is slightly forward of th=
e lower hinge. If not the beam would go to one side or the other and stay. =
Since you have a period (oscillation), the orientation should be ok. The bo=
om orientation with the earth shouldn't matter.

Regards
=0ABarry
=0Ahttp://www.seismicvault.com

--- On Sun, 12/6/09, Ted Channel  wrote:

From: Ted Channel 
Subject: Adjusting a Lehman
To: "psn" 
Date: Sunday, December 6, 2009, 5:02 AM

=0A=0A =0A =0A=0AHi Folks,=A0=A0 This is the basic process I =0Ause to adj.=
 a Lehman.=0A1.=A0 I assembly everything and level =0Aeverything.=A0=A0=A0 =
Once this is completed the vertical part of the =0Aframe is plumb.=A0=A0=A0=
The boom, and frame=A0are parallel with the =0Aearth and the boom is restin=
g on the centerline.=0A2.=A0 I time the period and start raising the =0Afro=
nt adjusting leg, tweaking the side adj. legs as necessary to maintain the =
=0Aboom on the center line.=A0 When I get a stable 20 second period I am =
=0Afinished.=0A=A0=0AThese are=A0my questions:=A0=A0=A0 When =0AI perform t=
his set up, the vertical frame member is now tilting backward, and =0Athe=
=A0mass end of the boom has be raised.=A0 Now the boom is no longer =0Apara=
llel to the earth.=0A=A0=0A1.=A0 "What would happen" if I extended the wire=
 =0Asupport, lowering the boom back to parallel to the earth, but not chang=
ing the =0Avertical member.=A0=A0 To my knowledge I have never done this, I=
 just =0Aleave the boom with mass end raised via the front adj. leg.=0A=A0=
=0A2.=A0 Should I make this adjustment, returning =0Athe boom to parallel, =
by lengthen the support wire?=0A=A0=0AI have tried it, but the adjustments =
Hi Ted
To me the important thing is that t=
he upper hinge is slightly forward of the lower hinge. If not the beam woul=
d go to one side or the other and stay. Since you have a period (oscillatio=
n), the orientation should be ok. The boom orientation with the earth shoul=
dn't matter.

Regards
=0ABarry
=0Ahttp://www.seismicvault.com
--- On Sun, 12/6/09, Ted Channel <tchannel@............><=
/i> wrote:

From: Ted Channel <tchann=
el@............>
Subject: Adjusting a Lehman
To: "psn" <psn-l@w=
ebtronics.com>
Date: Sunday, December 6, 2009, 5:02 AM

=0A=0A =0A =0A=0A
Hi Folks,   This is the basic process I =0Ause to ad=
j. a Lehman.
=0A
1.  I=
 assembly everything and level =0Aeverything.    Once this i=
s completed the vertical part of the =0Aframe is plumb.   Th=
e boom, and frame are parallel with the =0Aearth and the boom is resti=
ng on the centerline.
=0A
2=
..  I time the period and start raising the =0Afront adjusting leg, twe=
aking the side adj. legs as necessary to maintain the =0Aboom on the center=
 line.  When I get a stable 20 second period I am =0Afinished.<=
/div>=0A
 
=0A
These are my questions:   =
 When =0AI perform this set up, the vertical frame member is now tilting ba=
ckward, and =0Athe mass end of the boom has be raised.  Now the b=
oom is no longer =0Aparallel to the earth.
=0A
 
=0A
1.  "What would happen" if I extended the wire =0Asupport, lower=
ing the boom back to parallel to the earth, but not changing the =0Avertica=
l member.   To my knowledge I have never done this, I just =0Alea=
ve the boom with mass end raised via the front adj. leg.
=0A 
=0A
2.  Should I make this adjustment, returning =0Athe =
boom to parallel, by lengthen the support wire?
=0A
 
=0A
I have tried it, but the adjustments are so small I =0Acan't mea=
sure the results.
=0A
 
=0A
Thanks, Ted

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