Ted,

Think of the garden gate. When the top support is in Front of the bottom
support, the gate will come to rest at the point where top support is most
in front of the bottom support. Now as the top support is moved closer to
the bottom support (raising front support leg) the gate's resonant frequency
will get longer. Finally when the 2 supports line up, the gate will not
return to where you want it, or an unstable Lehman.

Gary

 

From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Ted Channel
Sent: Friday, April 23, 2010 11:09 AM
To: psn
Subject: Lehman set up

 

Hi Folks,   Many of you have more experience in setting up a Lehman.   I
have a basic question.   Let's assume the frame and the horz arm are
parallel.   The vertical column has two pivots points, for the arm, top and
bottom.   The bottom pivot is a roller on roller and is not adjustable.
The top pivot is a wire, which carries the weight of the arm.   This wire
has two adjustments.   One is a slip nut, which allow the suspension wire to
be shorten or lengthen, and keeps the arm parallel to the base.    (The next
adjustment on this top pivot wire is an adjustment screw which moves this
point forward or behind that of the bottom pivot)

 

This tilt off vertical is also controlled using the front adj. leg.

 

My question is "as a starting point, should the top pivot point be perfectly
vertical to the bottom pivot point"   Or should it be slightly behind or in
front of the bottom pivot point?

 

I have set up several Lehman's, and really not paid much attention to this.
I think I have always started with them vertical and used the front leg to
move the top point behind the bottom pivots.

 

I do know there's are lots of things to consider in this set up.   but I
would like your opinion on this point,   I think I understand the others.

 

Thanks, Ted














Ted,

Think of the garden gate. When the top support is in =
Front
of the bottom support, the gate will come to rest at the point where top
support is most in front of the bottom support. Now as the top support =
is moved
closer to the bottom support (raising front support leg) the gate's =
resonant
frequency will get longer. Finally when the 2 supports line up, the gate =
will
not return to where you want it, or an unstable =
Lehman.

Gary

 





From:=

psn-l-request@.............. [mailto:psn-l-request@............... On =
Behalf
Of Ted Channel

Sent: Friday, April 23, 2010 11:09 AM

To: psn

Subject: Lehman set up





 



Hi
Folks,   Many of you have more experience in setting up a
Lehman.   I have a basic question.   Let's assume =
the frame
and the horz arm are parallel.   The vertical column has two =
pivots
points, for the arm, top and bottom.   The bottom =
pivot is
a roller on roller and is not adjustable.   The top pivot is a =
wire,
which carries the weight of the arm.   This wire has two
adjustments.   One is a slip nut, which allow the suspension =
wire to
be shorten or lengthen, and keeps the arm parallel to the
base.    (The next adjustment on this top pivot wire is =
an
adjustment screw which moves this point forward or behind that of the =
bottom
pivot)





 





This
tilt off vertical is also controlled using the front adj. =
leg.





 





My
question is "as a starting point, should the top pivot point be =
perfectly
vertical to the bottom pivot point"   Or should it be =
slightly
behind or in front of the bottom pivot point?





 





I
have set up several Lehman's, and really not paid much attention to
this.    I think I have always started with them vertical =
and
used the front leg to move the top point behind the bottom =
pivots.





 





I
do know there's are lots of things to consider in this set =
up.   but
I would like your opinion on this point,   I think I =
understand the
others.





 





Thanks,
Ted