I had not seen it either. Then again, I'm about as far as an
"experienced hand" as you can get. But one of the towers I put up out
here in 2018 exhibited that unscrewing thing right before my eyes...
It was just on one guy, one tower leg, one of the 3 towers that went up
that day. We were roughing in the tower trim so I'm not sure how we
were set for "under tension" at the moment but they were not slack. I
suppose it must have just been the rare combo of that specific guy, the
bit of wind, the angle, the turnbuckle and whatever else - or maybe just
some luck. Seeing it made a believer out of me though.
Would not say it's going to happen often based on my ultra limited
experience - but I'm convinced after seeing it once with my eyes - guys
who don't use a safety wire are definitely walking on the wrong side of
the risk road given it's so damned easy to thread something in there to
prevent it.
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 4/14/20 9:48 PM, Steve Maki wrote:
The purpose of the safety wire is to prevent vandals from unscrewing
the turnbuckle. Some say that it's also to prevent the turnbuckle from
unscrewing due to vibration - but I've never seen that tendency in
turnbuckles under guy wire tension.
Properly sized turnbuckles are not the weak link in the system - it's
the guy wire itself.
-Steve K8LX
On 04/14/20 22:16 PM, K9MA wrote:
I ran into the same problem when I replaced my tower last year. I
used Big Grips on the guys, but wanted to use cable clamps on the
safety wire through the turnbuckles, which was to be 3/16 EHS. Except
for some bare iron ones, none of the clamps I could find were rated
for 1X7 EHS; all were rated for 7X19, etc, with more strands. I
think the key is that the saddles have to be malleable, because it's
impossible to compress 1X7 EHS. (Ever try to cut the stuff?) I
finally ended up buying some finely stranded SS cable and clamps for
the safety wires. Overkill, maybe, but if a turnbuckle fails, I want
the safety wire to hold the tower up.
73,
Scott K9MA
On 4/14/2020 17:05, Donald Chester wrote:
Keith Dutson kdutson at sbcglobal.net Sat Apr 4 19:28:59 EDT 2020
wrote:
Good reminder to always use hot dipped galvanized hardware.
I re-guyed my Rohn 25 a couple of years ago. Big Grips are great
for attaching insulators breaking up
guy cables on my 160m vertical, but I use wire rope clamps on the
chains of 3 insulators next to the
tower because with Big Grips the insulators would be spaced too far
apart for my liking.
I ordered new clamps from Rohn, but the ones I received were cheap
zinc plated like something from
Ace Hardware, and the saddles are so poorly made that they slipped
on the cable when I tested
them under tension using a ratchet puller. I called the Rohn dealer
and they told me they couldn't get
the good hot-dipped clamps any more, since almost everyone now uses
Big Grips exclusively. I looked
on line and the good hot-dipped clips from Crosby are very
expensive, about $7 each (mine cost me
35¢ each in 1980).
I ended up re-using the old ones after carefully inspecting each
one, and painted over them with a heavy
coat of Rustoleum aluminium paint. I used some of the crappy ones I
got from Rohn for another
(non-tower) project, and sure enough, the U-bolts and nuts are now
heavily rusted after only two years,
much more so than the original clamps I had installed nearly 40
years ago. The re-used and painted ones
on the tower guy wires still look as good as the day I installed
them. I have found that ordinary aluminium
paint lasts longer before rust begins to peer through, than the
"Cold-Galv" stuff.
I still have a bucket full of the crappy ones I got from Rohn.
Haven't decided whether to take them to
a hamfest and sell for whatever I can get for them, or to toss them
in the dumpster. I would hate for
someone else to buy them from me and have a tower fail when the
cables slipped during a heavy wind-
storm. I would have returned them if I hadn't fooled around and
waited more than a year before opening
the box when I was ready to use them, and discovering what they sent
me. I didn't bother, since I doubt
they would have accepted a return after I had waited that long.
Don k4kyv
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