I think Rohn has an interesting challenge for hollow leg fasteners. They
can't be tightened to the usual torque value for that size & grade bolt
since that would collapse the tubing too much. I was going to suggest
Nord-Lock locking washers which I used on my Rohn 65 legs. R65 flange
bolts can be tightened to the 5/8" A325 bolts torque spec (~100 ft-lbs)
and thus the Nord -Lock grips the nut surface. I doubt that could
happen with hollow legs without leg damage. see the test video
http://www.nord-lock.com/bolted/watch-the-new-junker-test-video-here/
There are several varieties of nuts with the dimples to distort the
threads. The bolt-nut pair with the distorted threads is a one time use
assembly as the intent is to damage the threads so they don't easily
come apart. If there is too much Zn in the nut threads, that is a
quality issue. Last time I saw real Rohn bolts they were grade 8, so
check the torque tables vs the bolt head stamp on your bolts and use
that torque for assembly with a torque wrench, not an impact wrench.
Whether locking fasteners are really needed is probably debatable in
light of all the towers still standing assembled without them. However,
lawyers and code bureaucrats help make us totally safe.
Grant KZ1W
On 1/25/2016 18:03 PM, StellarCAT wrote:
Sorry guys – I wasn’t clear ... the issue isn’t the bolt going in the hole. I have a taper pin and I know how that is done .... the
issue is the nut on the bolt! IT won’t go on. It – the nut, has 3 dimples that Rohn now stamps in to provide a locking mechanism. But its so
aggressive that once the dimpled part of the nut – the outside of the nut gets to the bolt you’re done turning at least with the larger bolts.
I don’t see how I can turn this without some form of air wrench and then all the galvanizing is going to be stripped off! I managed to get the nuts
on the small ones in place – small bolts that is – but it is pretty shiny where the threads are and not sure there’s a great deal of
zinc there.
Gary
K9RX
From: StellarCAT
Sent: Monday, January 25, 2016 5:24 PM
To: tower
Subject: Rohn Bolts
I’ve done a good share of towers over the years – all R45 (soon that will include a 55) ... both new and used ... and I’m starting to put a new tower up at my new
location. This is R45. It is used. I bought new Rohn (yes – Rohn) bolts and I’ve never had bolts that were SO tight before. These have a dimple on one side –
actually a set of 3. I’m sure it’s a self locking mechanism. You can’t thread them on at all starting with the dimpled face – they won’t go –
so I’m pretty sure I’m doing it the right way ... the small bolts went on with lots of effort seeming to strip the galvanizing off the bolt as they went on .. the large
ones don’t want to go much more than when the dimple gets on to the bolt.
Is this correct? Should I expect this much effort now with their new bolts? Boy if
one had to put up a good deal of sticks in a day their arms would feel it at the
end of it. Hate to have to haul an air wrench up there :>)
Gary
K9RX
[I called Hill Radio, where I got the bolts, and they called Rohn while I was on the phone (I didn’t talk to Rohn
myself) ... Rohn says yeah they’re tight but should be doable. They also said I’m probably putting them on
backwards – which isn’t possible as you can’t even thread them on on the dimple side!]
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