Topband: cable clamps on old Phillystran

[Grant Saviers]

In addition to my prior long term creep tests for loads to 11,000#, I've 
concluded a tension test to failure of the Crosby Spelter socket 
terminations for the older parallel strand Phillystran in 5/8" OD size 
and using West Marine 105 epoxy as the potting compound.  I was unable 
to source the "official" potting compound except at exorbitant cost and 
lead times from the manufacturer in the UK.

The smaller Chant tension test bed at West Coast Wire Rope was used 
($125 for 30 minutes).  The load was ramped in 2500# increments from 
12,500# and no short term creep was observed in a 2 minute dwell 
period.  At 20,000# load the machine was set to test to failure which 
occurred at 28,240#, beyond the rated 25,600# break strength of the 
Philly and near the 30,000# rated break strength of the Crosby socket.  
The failure occurred about 2" from a socket.  No extrusion of the epoxy 
from the socket or withdrawal of fibers from the epoxy were observed.

Hence, for my purposes the capabilities of this termination method far 
exceed the required 6700# break strength for the tower guys.

I remain convinced that cable clamps are not a reliable means for 
terminating older parallel strand Phillystran.   I also would not use 
the factory specified cable clamps on the 1200# rated current model 7x19 
style Phillystran cable, which is frequently used for boom guys.  That 
is a issue for later testing.

Contact me offline if you want my report on the test to failure. (call 
sign at arrl.net)

Grant KZ1W

caveat emptor etc.