[TowerTalk] Lockwasher Comparison

[Roger (K8RI) on TT]

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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-- 

73

Roger (K8RI)


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