In a message dated 2008/05/16, gel@................. writes:

> The typical Lehman uses an oil furnace nozzle as a connection point for the 
> upper end of the music wire that is attached to the boom. What method is 
> used to modify the nozzle in order to fasten the wire. What modifications are 
> made.

Hi Gary,

       The idea was to choose a music wire ~ the same diameter as the nozzle 
bore, but I don't know what that is. http://www.daddario.com/ list most of the 
music wires that are made. It is worthwhile getting wire which is nickel 
plated to minimise any rust problems.

       You might find it easier to clamp the wire between two washers? You do 
need to drill a hole for the wire through the centre of the clamp bolt.

       On system that I have used successfully is to mount the bottom SS ball 
bearing in the end of 3/8" bolt. I drill out a cone in the end of the bolt 
with a centre drill and stick the ball in place. Then I mount the bolt through 
the upright column with nuts and washers on both sides. This allows me to alter 
the horizontal position of the ball. I use a SS scalpel blade on the end of 
the arm as the hard counterface.
       The top suspension is another 3/8" bolt similarly fitted to the 
upright column. I file off about 3/8" of the threaded end of the bolt, about half 
way through and file just the thread off the other side of the bolt. I then 
drill a 1/8" hold in the centre of the flat and use an 1/8" bolt and two washers 
to clamp the music wire. 
       SS bearings are stocked by www.smallparts.com.
       I stroingly advise against trying to use a knife edge or a point 
suspension. Ball on a plane and crossed cylinder suspensions both give much better 
results. 
       These two adjustment bolts allow me to set up the seismometer so that 
it has a period of about 10 seconds when the baseplate is level. I then trim 
the period by raising the end of the base.
       Have a look at the school seismometers at 
http://www.jclahr.com/science/psn/chapman/school/MKII/index.html and at 
http://www.bgs.ac.uk/education/school_seismology/seismometer.html    
       The first one used eccentric washers to set the position of the top 
suspension.
       Make the seismometer as one unit with a long base. This is far easier 
to set up and to adjust than the types described on psn.
       I have used 3" x 1" U channl Aluminum for the frame and cross piece, 
with 1/8" thick triangular corner plates at the main joint. I use SS bolts in 
contact with the Al.

       Regards,

       Chris Chapman   
In a me=
ssage dated 2008/05/16, gel@................. writes:



The typical Lehman uses an oil=20=
furnace nozzle as a connection point for the upper end of the music wire tha=
t is attached to the boom. What method is used to modify the nozzle in order=
 to fasten the wire. What modifications are made.




Hi Gary,



       The idea was to choose a music wire ~ t=
he same diameter as the nozzle bore, but I don't know what that is. http://w=
ww.daddario.com/ list most of the music wires that are made. It is worthwhil=
e getting wire which is nickel plated to minimise any rust problems.



       You might find it easier to clamp the w=
ire between two washers? You do need to drill a hole for the wire through th=
e centre of the clamp bolt.



       On system that I have used successfully=
 is to mount the bottom SS ball bearing in the end of 3/8" bolt. I drill out=
 a cone in the end of the bolt with a centre drill and stick the ball in pla=
ce. Then I mount the bolt through the upright column with nuts and washers o=
n both sides. This allows me to alter the horizontal position of the ball. I=
 use a SS scalpel blade on the end of the arm as the hard counterface.

       The top suspension is another 3/8" bolt=
 similarly fitted to the upright column. I file off about 3/8" of the thread=
ed end of the bolt, about half way through and file just the thread off the=20=
other side of the bolt. I then drill a 1/8" hold in the centre of the flat a=
nd use an 1/8" bolt and two washers to clamp the music wire. 

       SS bearings are stocked by www.smallpar=
ts.com.

       I stroingly advise against trying to us=
e a knife edge or a point suspension. Ball on a plane and crossed cylinder s=
uspensions both give much better results. 

       These two adjustment bolts allow me to=20=
set up the seismometer so that it has a period of about 10 seconds when the=20=
baseplate is level. I then trim the period by raising the end of the base.
       Have a look at the school seismometers=20=
at http://www.jclahr.com/science/psn/chapman/school/MKII/index.html and at <=
BR>
http://www.bgs.ac.uk/education/school_seismology/seismometer.html  =
;  

       The first one used eccentric washers to=
 set the position of the top suspension.

       Make the seismometer as one unit with a=
 long base. This is far easier to set up and to adjust than the types descri=
bed on psn.

       I have used 3" x 1" U channl Aluminum f=
or the frame and cross piece, with 1/8" thick triangular corner plates at th=
e main joint. I use SS bolts in contact with the Al.



       Regards,



       Chris Chapman