In a message dated 23/04/2010, gmvoeth@........... writes:

I'm  curious about the hinge assembly,
Have you ever tried using a graphite  surface as your resting surface for 
the ball bearing ?

Hi Geoff,
 
    Graphite is not strong enough / hard enough. A ball  would dig into the 
surface.
    A good cheap system is to use a 1/2" SS ball on the  upright column and 
glue a clear bit of a SS scalpel blade to the end of the arm,  preferably 
with two component acrylic glue. Ordinary Epoxy tends to be too  brittle. 
Don't mount the ball on the end of the arm. It slips far too easily, at  only 
~5 degrees.

Have you  ever tried a flexible membrane instead of a bearing surface where 
two seperate  items
come in contact ?
If you have ever tried these before or do you  know of anyone who has ?
    The 1963 commercial Sprengnether horizontal used  flexing wires top and 
bottom. 
    Several commercial seismometers have used crossed  foils top and bottom.
    See also _http://jclahr.com/science/psn/cor_psn.html_ 
(http://jclahr.com/science/psn/cor_psn.html)  

 
    Regards,
 
    Chris Chapman





In a message dated 23/04/2010, gmvoeth@........... writes:
I'm=20
  curious about the hinge assembly,
Have you ever tried using a graphit=
e=20
  surface as your resting surface for the ball bearing ?

Hi Geoff,
 
    Graphite is not strong enough / hard enough.=
 A ball=20
would dig into the surface.
    A good cheap system is to use a 1/2" SS ball=
 on the=20
upright column and glue a clear bit of a SS scalpel blade to the end of th=
e arm,=20
preferably with two component acrylic glue. Ordinary Epoxy tends to be too=
=20
brittle. Don't mount the ball on the end of the arm. It slips far too easi=
ly, at=20
only ~5 degrees.
Have you=20
  ever tried a flexible membrane instead of a bearing surface where two se=
perate=20
  items
come in contact ?
If you have ever tried these before or do=
 you=20
  know of anyone who has ?
    The 1963 commercial Sprengnether horizontal=
 used=20
flexing wires top and bottom. 
    Several commercial seismometers have used cro=
ssed=20
foils top and bottom.
    See also http://jclahr.com/science/psn/cor_psn.html 

 
    Regards,
 
    Chris Chapman