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?  Spec=
ifically the lower wire hinge.  The piece is a short wire with a round bras=
s fitting at each end.  I tried to make it myself using piano wire and roun=
d 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 pu=
rchased at the hobby shop keep breaking,  Also, any advice on drilling an a=
pproximately .030 diameter hole in round brass stock would also be apprecia=
ted.=20
James Allen

=20

Hi James,=20
=20
    The smallest drills that I can buy off the shelf are 13.5 thou. I sugge=
st that you use steel bits. The tungsten carbide ones are VERY brittle - an=
d expensive. You need a miniature high speed drill, a drill press and a sma=
ll vice to clamp the workpiece. I use a 1/8" chuck 12 V Reliant drill runni=
ng at about 8,000 RPM, bought for drilling PCBs. Centre punch the end of th=
e 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 lubr=
icant. 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 sold=
er 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 operat=
ors 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 act=
ual wire diameter used ? The nearest piano wire size seems to be 0.025".=20
=20
    Regards,=20
=20
    Chris Chapman


















=
From: JAMES C ALLEN jcallen1@verizo=
n.net

Sent: Thu, 5 Apr 2012 5:56

Subject: Re: SPREGNETHER HORIZONAL SEISMOMETER











Does anyone have pa=
rts for an old Spregnether horizontal seismometer?  Specifically the l=
ower 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 br=
ass 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 p=
urchased at the hobby shop keep breaking,  Also, any advice on drillin=
g an approximately .030 diameter hole in round brass stock would also be ap=
preciated. 


James Allen






 







Hi James, 





 





    The smallest drills that I can buy=
 off the shelf are 13.5 thou. I suggest that you use steel bits. The tungst=
en 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.&nb=
sp;I use a 1/8" chuck 12 V Reliant drill running at about 8,000 RPM,&n=
bsp;bought for drilling PCBs. Centre punch the end of the brass rod and low=
er the running drill SLOWLY and drill the metal SLOWLY, with frequent withd=
rawls to clear the swarf. You do NOT use any oil or lubricant. It should NO=
T 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 fin=
e 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 resid=
ues. 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 t=
he origional flex link as accurately as possible. I use sliding callipers a=
ccurate to 0.5 thou. What was the actual wire diameter used ? The near=
est piano wire size seems to be 0.025". 





 





    Regards, 





 





    Chris Chapman