They are commonly available as distorted thread nuts
http://www.mcmaster.com/#hex-nuts/=13hjsuv
They are one time use, and most make the bolt a one time use as well.
One way, if not the cheapest way, to make a locking nut.
Grant KZ1W
On 7/28/2016 21:09 PM, Hans Hammarquist via TowerTalk wrote:
When I put up my tower, the sections were bolted together with a special self
locking nut. The nuts had three dents in them and there were friction that made
it necessary to use a wrench to put them in place. The tower doesn't shake or
vibrate that much but I have a tough time to imagine these nut will unscrew
themselves.
Anyone else with experience with these kind of lock nuts?
Hans - N2JFS
-----Original Message-----
From: Roger (K8RI) on TT <K8RI-on-TowerTalk@tm.net>
To: towertalk <towertalk@contesting.com>
Sent: Thu, Jul 28, 2016 10:31 pm
Subject: Re: [TowerTalk] Lockwasher Comparison
There are Helicoil steel thread replacement inserts that work really
well and were inexpensive the last time I used them.
Others like Nordlocks, while I've had very bad luck with them. We are
nowhere near being downwind from industrial centers with the Chicago
area at near 200 miles, but the Nylon inserts just seem to dissolve away
in a year or two. None have made it past two years. I'd like them if
they'd last, but here? They are short term only. If the threads are shot
a bolt through from the inside with the head epoxied in place has worked
for me as a stud. The mount to accessory plate is not precision and
there are usually enough threads left to screw the bolt through.
I can find no reason for their short life. I thought it was IR as nylon
rope breaks down and gets stiff out in the weather, but others in areas
with far more sunshine than we have said they had no problems.
I'd advise drilling a small drain hole, but not large enough for
Muddobbers to get in. They ruined the matching network on an AV640 for me.
The SS bolt with NordLock nuts would be ideal if I could get them to last.
73
Roger (K8RI)
On 7/28/2016 Thursday 3:48 AM, Ian White wrote:
Grant KZ1W wrote:
Another place I use Nordlocks is for rotator base bolts. Since
aluminum
has about 2x the expansion per degree F as steel (alloys and temper
make
big differences), there is temperature cycling of the bolt load. It is
also the case that I don't want to mess with Loctited bolts when on the
tower, but with the cautions, it works. Used rotators I've bought
always
seem to have roughed up base threads, and a Helicoil insert is the
ultimate fix, since they are stronger than the raw aluminum threads.
If the threads in aluminium rotator castings aren't too badly damaged, a
simple alternative is to use RED Loctite to fix short threaded studs
permanently into the rotator base. (Even better, insert set-screws from
inside the base casting to leave protruding studs, and again use Red
Loctite.) During installation, the studs pass through the holes in the
tower plate, locating the rotator safely in its correct position even
before you add the nuts and washers.
Nylocks everywhere else.
Make that NEW Nylocs, every time.
Threaded studding can also be used to rescue damaged threads in the bell
casting on Ham-IV and similar rotators. Again, clean out the threads and
insert stainless steel studs, fixed permanently in place using Red
Loctite. Then use Nyloc nuts to secure the two castings together.
(Because the original self-tapping screws cause corrosion damage in the
aluminium casting, you may need to re-tap the holes to a slightly larger
size. Although you may lose some thread engagement, the Red Loctite will
help fill the gaps.)
73 from Ian GM3SEK
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