PSN-L Email List Message
Subject: Re: My First Lehman
From: "meredith lamb" paleoartifact@.........
Date: Sun, 8 Jun 2008 22:36:34 -0600
Hi Gary,
I'am overall impressed! Many thanks for the pictures!
I enlarged your photo of the pivot with the free Picasa2 from Google. Its =
a
interesting new (too me) method of being able
to center the ball bearing over the width of the mast. With the ball
bearing centered inbetween two of the four
pins; you're getting two contacts on the ball bearing....which is a "crosse=
d
rod" pivot essentially...which is a very good
low friction type of pivot; but they can wander one way or the other down
their "guide channel" over time.
I would think with the mass entending beyond the front leveling
setscrew...the overall platform stability could be balance
conpromised by stress somewhat. You would likely be forced to use the
Chapman magnet system off the aluminum base
plate.....or.......pull the mass in; shorten the upper pivot wire
attachment, install the magnet assemblys; and likely settle
for a lesser long period. Then again....one might add on (or replace the
base) out with more aluminum, and the leveling
setscrew further out also.
Take care, Meredith Lamb
On Sun, Jun 8, 2008 at 7:31 PM, Gary Lindgren wrote=
:
> I have some pictures for the first Lehman. At this point I'm just gettin=
g
> familiar with it and learning how to set it up. I have 2 sets of crossbar=
s,
> one set is 1/8" SS dowel pins and the other is 1/8" hardened steel dowel
> pins. So far I think I like the hardened steel better. The upper mounting
> uses the idea from Ted, he suggested using a =BC-20 acorn nut. This worke=
d
> perfect, I drilled a .020" hole in the center to receive the .017" dia.
> music wire. A nice snug fit. Then I use a =BC" dia. Si3N4 ball bearing. T=
he
> ball bearing grade is 5, so it is very smooth and very hard, much harder
> than steel. So far I have been able to achieve just under 30 sec. resonan=
t
> period. I'll be using the *Chapman* magnet system for both the sensor and
> damping. The Lehman is shown here
> http://gelindgren.googlepages.com/lehman_6_8_08.jpg The bearing detail=
:
> http://gelindgren.googlepages.com/lehman_bearing_6_8_08.jpg The upper
> mounting: http://gelindgren.googlepages.com/lehman_upper_mount_6_8_08.jpg=
and lower mounting:
> http://gelindgren.googlepages.com/lehman_lower_mount_6_8_08.jpg
>
>
>
> Suggestions are welcome,
>
> Gary
>
>
>
>
>
>
>
>
>
>
>
> *Gary Lindgren***
>
> *585 Lincoln Ave***
>
> *Palo Alto CA 94301***
>
>
>
> 650-326-0655
>
>
>
> www.blue-eagle-technologies.com
>
> cymonsplace.blogspot.com
>
>
>
>
>
Hi Gary,
I'am overall impressed! Many thanks for the pictu=
res!
I enlarged your photo of the pivot with the free Picasa2 from G=
oogle. Its a interesting new (too me) method of being able
to cent=
er the ball bearing over the width of the mast. With the ball bearing=
centered inbetween two of the four
pins; you're getting two contacts on the ball bearing....which is a &qu=
ot;crossed rod" pivot essentially...which is a very good
low fricti=
on type of pivot; but they can wander one way or the other down their "=
;guide channel" over time.
I would think with the mass entending beyond the front leveling setscre=
w...the overall platform stability could be balance
conpromised by stres=
s somewhat. You would likely be forced to use the Chapman magnet sys=
tem off the aluminum base
plate.....or.......pull the mass in; shorten the upper pivot wire attachmen=
t, install the magnet assemblys; and likely settle
for a lesser long per=
iod. Then again....one might add on (or replace the base) out with mo=
re aluminum, and the leveling
setscrew further out also.
Take care, Meredith Lamb
On Sun, Jun 8, 2008 at 7:31 PM, Gary Lindgren <
gel@.................> wrote:
<=
blockquote class=3D"gmail_quote" style=3D"border-left: 1px solid rgb(204, 2=
04, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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