[TowerTalk] STAINLESS STEEL BOLT AND ALUMINIUM ROTATOR CASINGPROBLEM

Ian White GM3SEK gm3sek at ifwtech.co.uk
Tue Nov 15 01:25:21 PST 2011



>On 11/14/2011 1:49 PM, john at kk9a.com wrote:
>> There is tremendous corrosion to aluminum when in contact with stainless
>> steel and salt spray.  As much as I like stainless steel hardware, I would
>> still avoid using it in aluminum threads if you're in a corrosive
>> environment.
>>
>> John P40A
>>
>
>I had heard the same thing.  Stainless seems OK in aluminum under
>ordinary conditions, but the Navy has a "salt spray" test that
>this combination fails.
>
>Rick N6RK

One solution is to fix stainless studs into the threaded holes, using a 
permanent thread-locking compound. The studs pass clear through the 
holes in the lower part of the rotator shell and can be secured from 
below by stainless nyloc nuts, which can always be easily removed.

As well as fixing the studs into the threaded holes, the locking 
compound permanently seals the aluminum/stainless thread interface and 
protects it from any further corrosion.

One final point: this modification is easiest, and works the best, if 
it's done *before* the aluminum threads have become seriously damaged. 
Otherwise you're into re-threading the holes to a larger size, which 
then brings further problems about clearances.


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek


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