[R-390] Gear lube suggestions

[Gary Pewitt]

Since the unavailability of whale oil, which was totally non gumming, 
the only substitute is Jojoba oil, which is also non gumming.  It's 
really good stuff.


On 7/15/2013 9:28 PM, Roger Ruszkowski wrote:
>
>
>
> -----Original Message-----
> From: Charles P. Steinmetz <charles_steinmetz at lavabit.com>
> To: 390 list <r-390 at mailman.qth.net>
> Sent: Mon, Jul 15, 2013 8:12 pm
> Subject: Re: [R-390] Y2K Manual Question
>
>
> Don wrote:
>
>> MIL-L-7870 is a general purpose, stable at low temp., instrument oil with
>> anti-oxidation properties.  That part number is superseded by part number
>> MIL-PRF-7870.  7870[D] seems to be the last available revision and Royco
>> lists that oil as commercial part 363.  Anyone disagree with my conclusion
>> that 7870 is the proper citation?
> Good detective work!
>
>> He likes dry, I like a little Mobile-1
> I have used both light oil and dry graphite with good success (when I
> use graphite, I apply it dry, not in a solvent carrier -- I found
> that the graphite left after the solvent evaporated did not lubricate
> nearly as well as graphite applied dry).  The primary application for
> graphite is in very dusty locations (sandstorms, etc.), where the
> dust can get caught in oil to form an abrasive paste.  This may be
> why your friend doesn't use oil.  If so, he should consider keeping
> the radio room cleaner (if dust getting caught in the oil is really a
> problem for him) or using graphite.  You can get by with an
> unlubricated gear train, but it is not the preferred solution.  (I
> have only once or twice seen a 390/390A used by a ham or SWL where
> dust in the oil was a problem, out of several hundred units.)
>
> When using oil, the lubricity demands are not high -- the tuning
> mechanism is very lightly loaded -- so you don't need extreme
> pressure or high-speed additives.  The most important criterion is
> that it be non-gumming over long periods of time and at somewhat
> elevated temperature.  Second is some corrosion inhibitor, given the
> different metals used in the gear train.  I'm sure there are many
> oils that fit this description.  I've been using and recommending
> Mobil 1 for 390/390A gear trains (and many other uses) since the
> mid-'70s and it is well-proven.
>
> I have generally avoided grease of any sort, because until very
> recently there weren't any that were as gum-resistant as a fine light
> synthetic oil.  There are some specialized greases available today
> that meet the requirement (e.g., some of the DuPont Krytox products),
> although the ones that do are quite expensive and I see no benefit
> generally to grease over light oil.
>
> Best regards,
>
> Charles
>
>
> Amen,
>
> Good stuff Charles
>
> Roger
>
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-- 
Gary Pewitt   N9ZSV
1500 French Prairie Rd
Booneville, AR  72927