Dave 
 I have built 12 or 14 of the Leaman type detectors using pipe fittings.
My personal experience indicates that 1/2" pipe fittings are big enough.
Mine are very simple . The fittings consist of two 1/2" flange fittings
to bolt to the base . Two 1/2' l fittings ,one 4"nipple and two pieces of
pipe threaded on both ends 14 " or 16" long. 
    Keep it simple. Be sure to thread the pipe into the connectors the
same depth. Build the assembly up before bolting to the base. If one side
is longer than the other, back out or tighten  to make the sides even.
 Yes, yes , yes , some pipe fittings are different ,Some pipe will go
deeper into the fittings than the others. As long as it is rigid and the
right height, it is ok. Be innovative. Good luck.
                                                                        
John c cole
________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
http://dl.www.juno.com/get/tagj.
__________________________________________________________

Public Seismic Network Mailing List (PSN-L)