I had trouble putting together the pipe fittings
listed on the "Homebuilt Seismograph - FAQ"
on Larry Cochrane's site:=20

>Following instructions in the article a very sensitive horizontal
>sensor can be made for under $50.00 from parts available from the
>local hardware store. The parts list should be 3/4" pipe fittings
>and include:
>     2  flanges for bolting the assembly to a base.
>     2  3/4"  T fittings
>     2  3/4"  90 degree elbows
>     1  3/4"  union
>     4  3/4"  nipples 2" long
>     2  3/4"  nipples 6" long                       ___
>     1  3/4"  nipple  5" long=20

I got my parts from my local Home Depot
but when I screwed them together the upper
5" nipple was 1/2" too short.  I need a 5 1/2"
nipple there.  I could not find a 5 1/2", so I
ended up with a 4 1/2" nipple on top and=20
two 1 1/2" nipples below on the horizontal=20
sections.

Am I doing something stupid or perhaps there
is a variation in length between 3/4" unions made by
different manufacturers?  My union is 2.1" long.

Dave                     =20



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