Chris,
Thank you for the fine pictures. Yes, I throw out the idea of using the oil
furnace nozzle. For the ball bearing I'm going to use a ceramic ball
bearing. It is extremely hard and then I will use 2 crossed hardened dowel
pins on the vertical post.
Gary Lindgren
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of ChrisAtUpw@.......
Sent: Friday, May 16, 2008 4:45 PM
To: psn-l@..............
Subject: Re: Oil Furnace Nozzle Connection
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
Chris,
Thank you for the fine pictures. Yes, I throw out the =
idea of
using the oil furnace nozzle. For the ball bearing I’m going to =
use a
ceramic ball bearing. It is extremely hard and then I will use 2 crossed =
hardened
dowel pins on the vertical post.
Gary Lindgren
From:=
=
psn-l-request@..............
[mailto:psn-l-request@............... On Behalf Of =
ChrisAtUpw@.......
Sent: Friday, May 16, 2008 4:45 PM
To: psn-l@..............
Subject: Re: Oil Furnace Nozzle Connection
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 &n=
bsp;
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