Thanks Chris.  Your clear and detailed recommendations  sure make sense =
to me.  However, with my age and infirmities and the lack of a drill =
press I have been fortunate in Jim Hannon, who has the equipment, to =
offer to do it for me.  I really appreciate your thoughtful =
recommendations and all the list members who have been so responsive and =
kind with their suggestions.  It truly is great to be a part of a hobby =
and list with such wonderful people such as you.
Thank you so much.
James Allen=20

From: chrisatupw@..........
Sent: Thursday, April 05, 2012 6:16 PM
To: psnlist@.................
Subject: Re: SPREGNETHER HORIZONAL SEISMOMETER

From: JAMES C ALLEN jcallen1@...........
Sent: Thu, 5 Apr 2012 5:56
Subject: Re: SPREGNETHER HORIZONAL SEISMOMETER


Does anyone have parts for an old Spregnether horizontal seismometer?  =
Specifically the lower wire hinge.  The piece is a short wire with a =
round brass fitting at each end.  I tried to make it myself using piano =
wire and round brass stock.  But drilling the round brass stock to =
insert the wire into has been fraught with failure thus far since the =
very small drill bits I purchased at the hobby shop keep breaking,  =
Also, any advice on drilling an approximately .030 diameter hole in =
round brass stock would also be appreciated.=20
James Allen

Hi James,=20
    The smallest drills that I can buy off the shelf are 13.5 thou. I =
suggest that you use steel bits. The tungsten carbide ones are VERY =
brittle - and expensive. You need a miniature high speed drill, a drill =
press and a small vice to clamp the workpiece. I use a 1/8" chuck 12 V =
Reliant drill running at about 8,000 RPM, bought for drilling PCBs. =
Centre punch the end of the brass rod and lower the running drill SLOWLY =
and drill the metal SLOWLY, with frequent withdrawls to clear the swarf. =
You do NOT use any oil or lubricant. It should NOT be a really difficult =
job, but you probably can't use a hand held Dremel drill. Assuming that =
you are soldering the wire in place, clean it with fine emery paper and =
tin the ends with a fairly active solder paste. Then wash / scrub the =
flux off and assemble the joint with rosin cored circuit board solder =
and a different soldering iron - you don't want any corrosive residues. =
Sorry that I can't be of more practical help - I am on the wrong side of =
the Atlantic ! Do you know any local HAM radio operators who might have =
a circuit board press drill ?
    Do check the exact dimensions of the origional flex link as =
accurately as possible. I use sliding callipers accurate to 0.5 thou. =
What was the actual wire diameter used ? The nearest piano wire size =
seems to be 0.025".=20
    Regards,=20




Thanks Chris.  Your clear and detailed recommendations  =
sure make=20
sense to me.  However, with my age and infirmities and the lack of =
a drill=20
press I have been fortunate in Jim Hannon, who has the equipment, to =
offer to do=20
it for me.  I really appreciate your thoughtful recommendations and =
all the=20
list members who have been so responsive and kind with their =
suggestions. =20
It truly is great to be a part of a hobby and list with such wonderful =
people=20
such as you.
Thank you so much.
James Allen 


 

From: chrisatupw@....... 
Sent: Thursday, April 05, 2012 6:16 PM
To: psnlist@.............. 
Subject: Re: SPREGNETHER HORIZONAL =
SEISMOMETER
 







From:=20
JAMES C ALLEN jcallen1@...........
Sent: =
Thu, 5 Apr=20
2012 5:56
Subject: Re: SPREGNETHER HORIZONAL SEISMOMETER





Does anyone have =
parts for=20
an old Spregnether horizontal seismometer?  Specifically the lower =
wire=20
hinge.  The piece is a short wire with a round brass fitting at =
each=20
end.  I tried to make it myself using piano wire and round brass=20
stock.  But drilling the round brass stock to insert the wire into =
has been=20
fraught with failure thus far since the very small drill bits I =
purchased at the=20
hobby shop keep breaking,  Also, any advice on drilling an =
approximately=20
..030 diameter hole in round brass stock would also be appreciated. =

James Allen


 


Hi James, 

 

    The smallest drills that I can buy off =
the shelf=20
are 13.5 thou. I suggest that you use steel bits. The tungsten carbide =
ones are=20
VERY brittle - and expensive. You need a miniature high speed drill, a =
drill=20
press and a small vice to clamp the workpiece. I use a =
1/8" chuck=20
12 V Reliant drill running at about 8,000 RPM, bought for drilling PCBs. =
Centre=20
punch the end of the brass rod and lower the running drill SLOWLY and =
drill the=20
metal SLOWLY, with frequent withdrawls to clear the swarf. You do NOT =
use any=20
oil or lubricant. It should NOT be a really difficult job, but you =
probably=20
can't use a hand held Dremel drill. Assuming that you are soldering the =
wire in=20
place, clean it with fine emery paper and tin the ends with a fairly =
active=20
solder paste. Then wash / scrub the flux off and assemble the joint with =
rosin=20
cored circuit board solder and a different soldering iron - you don't =
want any=20
corrosive residues. Sorry that I can't be of more practical help - I am =
on the=20
wrong side of the Atlantic ! Do you know any local HAM radio operators =
who might=20
have a circuit board press drill ?


    Do check the exact dimensions of the =
origional=20
flex link as accurately as possible. I use sliding callipers accurate to =
0.5=20
thou. What was the actual wire diameter used ? The nearest piano wire =
size seems=20
to be 0.025". 

 

    Regards, 

 

    Chris=20
Chapman