In a message dated 2008/06/09, gel@................. writes:

> I have some pictures for the first Lehman. At this point I=E2=80=99m just=20=
getting=20
> familiar with it and learning how to set it up. I have 2 sets of crossbars=
,=20
> one set is 1/8=E2=80=9D SS dowel pins and the other is 1/8=E2=80=9D harden=
ed steel dowel pins.=20
>=20

Hi Gary,

       Ordinary steel will corrode in the damp air during rolling contact.=20
They are OK for trying out, but they won't last long. Are the SS dowel pins=20
hardened, ground and polished? Can you get them in something like type 415=20
martensitic SS? Incidentally, you can buy martesitic SS rod quite easily, bu=
t you=20
would have to harden it.

So far I think I like the hardened steel better. The upper mounting uses the=
=20
idea=20
> from Ted, he suggested using a =C2=BC-20 acorn nut. This worked perfect, I=
=20
> drilled a .020=E2=80=9D hole in the center to receive the .017=E2=80=9D di=
a. music wire. A nice=20
> snug fit.=20

       If this works, fine! I use thinner nickel plated music wire, 8 to 12=20
thou OD. I fit an L bracket at the top of the column with a horizontal hole=20=
in=20
it. I fit a bolt with a hole bored through the centre and clamp the wire=20
between flat washers. This seems to work OK.

       Then I use a =C2=BC=E2=80=9D dia. Si3N4 ball bearing. The ball bearin=
g grade is 5,=20
so it is very=20
> smooth and very hard, much harder than steel. So far I have been able to=20
> achieve just under 30 sec.resonant period. I=E2=80=99ll be using the Chapm=
an magnet=20
> system for both the sensor and damping. The Lehman is shown here=20
> http://gelindgren.googlepages.com/lehman_6_8_08.jpg    The bearing detail:=
 =20
> http://gelindgren.googlepages.com/lehman_bearing_6_8_08.jpg  The upper mou=
nting:=20
> http://gelindgren.googlepages.com/lehman_upper_mount_6_8_08.jpg  and lower=
 mounting:=20
> http://gelindgren.googlepages.com/lehman_lower_mount_6_8_08.jpg =20

       If you are getting 30 seconds, that is great.=20

       Regards,

       Chris Chapman  =20
In a me=
ssage dated 2008/06/09, gel@................. writes:



I have some pictures for the fi=
rst Lehman. At this point I=E2=80=99m just getting familiar with it and lear=
ning how to set it up. I have 2 sets of crossbars, one set is 1/8=E2=80=9D S=
S dowel pins and the other is 1/8=E2=80=9D hardened steel dowel pins. 



Hi Gary,



       Ordinary steel will corrode in the damp=
 air during rolling contact. They are OK for trying out, but they won't last=
 long. Are the SS dowel pins hardened, ground and polished? Can you get them=
 in something like type 415 martensitic SS? Incidentally, you can buy martes=
itic SS rod quite easily, but you would have to harden it.



So far I think I like the hardened steel better. The upper mounting uses the=
 idea 

from Ted, he suggested using a=
 =C2=BC-20 acorn nut. This worked perfect, I drilled a .020=E2=80=9D hole in=
 the center to receive the .017=E2=80=9D dia. music wire. A nice snug fit. <=
/FONT>=




       If this works, fine! I use thinner nic=
kel plated music wire, 8 to 12 thou OD. I fit an L bracket at the top of the=
 column with a horizontal hole in it. I fit a bolt with a hole bored through=
 the centre and clamp the wire between flat washers. This seems to work OK.<=
BR>


       Then I use a =C2=BC=E2=80=9D dia. Si3N4=
 ball bearing. The ball bearing grade is 5, so it is very 

smooth and very hard, much har=
der than steel. So far I have been able to achieve just under 30 sec.resonan=
t period. I=E2=80=99ll be using the Chapman magnet system for both th=
e sensor and damping. The Lehman is shown here http://gelindgren.googlepages.com/lehman_=
6_8_08.jpg    The bearing detail:  http://gelindgren.goo=
glepages.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  




       If you are getting 30 seconds, that is=20=
great. 



       Regards,



       Chris Chapman