Thanks to all for the advice.
The procedure was easier than I expected. I had two come-alongs already, so
I got a third. That simplified the process and made it faster. I used my
Klein grip to attach one of the come-alongs and the dynamometer, and used
wire rope clips to attach the cables of the other two come-alongs to their
respective guys. The clips had to be tightened well to keep the guy from
slipping, but did not leave any marks or distortion in the EHS. Whatever the
means of attachment, it's important to put it well ahead of where the grip
will be installed, but not so far (high) that it can't be reached.
I used the Dillon Dynamometer to calibrate the Loos PT-2 gauge. Here are the
results:
Loos Loos Dillon
Reading Chart Reading
26 450 300
27 500 400
30 660 450
31 720 500
32 780 600
33 840 660
34 900 700
35 1000 765
36 1100 850
37 1200 1000
As you can see, the Loos reads higher than the dynamometer, but not by a
heck of a lot. I only used the dynamometer to set the initial tension and
calibrate the Loos. Once I put the grips on and removed the come-alongs, I
used the Loos for setting the final tension.
I used the come-alongs to plumb the tower and set the tension to 600 lbs.
Then I installed the grips halfway and used the turnbuckles to increase the
tension to 1000 lbs, which is 15% of breaking strength for 6700 lb
Phillystran. This is the setting recommended on the Phillystran website.
They say the material will "relax" over a period of a few days,
automatically reducing the tension to 10%. See
http://www.phillystran.com/165.htm, "Tensioning Procedures" for more info.
I had initially set the turnbuckles to have 1"-2" of thread engaged on each
rod. I only had to close the turnbuckle by about 2" (i.e., 1" per rod) to
increase the tension from 600 to 1000 lbs. So each rod has about 2" or so of
thread in the turnbuckle. Since tensioning the upper guys will probably
cause the equalizer plate to put more tension on the bottom guys, I'll
probably have to back the turnbuckles out a little. In retrospect, it might
have been better to start will the turnbuckles screwed in a little more. I
did end up closing the grips all the way, but since I've only done that once
I can redo them if it looks like I don't have enough thread left in the
turnbuckle.
40' in the air -- only 70' more to go!
73, Dick WC1M
> -----Original Message-----
> From: K7LXC@aol.com [mailto:K7LXC@aol.com]
> Sent: Monday, November 13, 2006 3:34 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Installing and tensioning guywires
>
>
> In a message dated 11/12/2006 6:43:07 A.M. Pacific Standard
> Time, towertalk-request@contesting.com writes:
>
> > Hi. Finally started stacking my 110' Rohn 55 tower. We
> have 40' up
> > with
> two
> sets of temporary guys (AB-577 stainless guys, actually,
> which work nicely for temps.) The permanent guys are attached
> to the guy bracket at 33' and are ready to be connected to
> the anchors and tensioned. The guys are Phillystran, but
> with EHS leaders at the bottom. I'm using Big Grips.
>
> > I'm curious about the detailed sequence for tensioning
> the guys. I
> > have
> one
> Klein grip and one come-along. I also have a Dillon
> Dynamometer and a Loos gauge. I think I understand the
> general sequence for tensioning one guy:
>
> > 1. Attach one end of come-along to guy anchor
> 2. Attach other end of come-along to Klein grip 3. Attach
> Klein grip to EHS ahead of where the big grip is likely to
> end 4. Unscrew turnbuckle most of the way, leaving about 1-2"
> of thread (I'm using 12" turnbuckles) 5. Use come-along to
> tension the guy near the final pre-tension figure.
> 6. Install shackle, thimble and big grip on free end of guy.
> 7. Release come-along.
> 8. Use turnbuckle to reach final pre-tension.
>
> > As for determining tension, my plan is to put the Dynamometer in
> > line with
> the come-along and use it in step 5 and to calibrate the
> Loos gauge. That way, I can use the Loos gauge to determine
> tension after I've removed the come-along and Dynamometer.
>
>
> The sequence is fine. The Loos gauge is pretty accurate
> as is but no harm in checking it against your Dillon.
> Actually I wouldn't even bother with the Dillon. The Loos is
> accurate enough and all you have to do is hang it on the
> guywire without messing around with the comealong et al.
>
> You can pull a guywire by hand enough to put a little
> tension on it. Do that with all 3 and then take a
> measurement. For pre-tension, you just want all of them to
> be the same regardless of real tension. Once the tower is
> plumb, from there just do equal turns of the turnbuckles.
> It's easier if you've got someone on each guy and tell them
> "4 more turns" or whatever until you've got the desired
> tension. I usually don't do the final plumb-and-tension
> until the tower is done.
>
> > What I'm not sure about is how to approach doing all
> three guys. If
> > I
> tension the first guy near to the final pre-tension figure,
> as in step 5, then it seems to me that the tower will be
> pulled off plumb, and I might not be able to pull it back by
> tensioning the other guys.
>
> See comments above. Install the first one with a little
> tension and the other 2 the same way. Then go back and put
> some measurable pre-tension on them. You won't have enough
> initial tension to worry about.
>
> > But if I don't put
> enough tension on the first guy, then I might run out of
> thread on its turnbuckle. It would seem like this is an
> iterative procedure, and that it might require unclamping and
> retensioning each cable several times.
>
> That's where 3 comealongs and 3 grips comes in real
> handy, but it's not absolutely necessary. You'll have enough
> scope in your turnbuckle to handle it. Don't put the
> PreFormed grip on all the way. Just wrap it 1/2 way to begin
> with. That way there'll be enough holding power to hold the
> tower up but it'll come off easily if you have to move the
> guywire. I don't do the grip final wrapping until the tower
> is finished.
>
> > But to
> do that, I'd have to install, undo and reinstall the big
> grips several times, which is not good.
>
> You can unwrap the grip twice, giving you 3 tries to get
> it right.
> That's usually enough.
>
> > Am I worrying needlessly about this (i.e., there will be enough
> > turnbuckle
> thread) or is there a trick to this?
>
>
>
> Yes, you're worrying a little too much. It's got a
> little bit of a learning curve but it'll be close enough
> after you've been thru an iteration or two and everything's
> fixable so you'll eventually be successful.
>
> Cheers & GL,
> Steve K7LXC
> TOWER TECH -
> Professional tower services for hams
> Cell: 206-890-4188
>
>
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