[R-390] More geartrain rebuild info

Bob Camp ham at cq.nu
Thu Feb 24 21:14:33 EST 2005 

Hi

I have tried gear trains with the soak it out approach and and then 
popped them apart. When I have done so There has been grit in some of 
the split gears. I have not found a really good way to get grit out of 
them without taking them apart. Getting old lubricant out seems to go 
pretty well with various solvents. Depending on the radio you may or 
may not need to pop apart all the gears. As long as you can keep the 
parts all straight I guess I can't see any problem with taking the 
gears apart. It's enough work just to strip the whole gear train apart 
that the added work to separate the gears never seemed like a whole lot 
more effort.

Truth in advertising - yes I have seen some grubby gear trains. Not all 
gear trains seem to have the same level of fine dust embedded in the 
lubricant.

Splitting the gears apart does is it lets you get a nice uniform layer 
of the Mobil gear lube on the inside of the gear. I will admit that I 
have no idea if there is any more uniformity doing it that way than 
just trying to "ooze" in in from the edges.

Finally there is the "the refrigerator door is closed but is the light 
*really* turned off? You soak the gears in cleaner. You blow the 
cleaner off. You lube the gears. If you don't take the gears apart how 
can you be sure there is no cleaner left inside the gears? Of course 
you can simply *trust* that the light turned off ....

	Take Care!

		Bob Camp
		KB8TQ




On Feb 24, 2005, at 8:41 PM, Cecil Acuff wrote:

> Did we ever come up with a video or a series of pictures detailing the 
> reassembly of the gear train.  I am faced with the prospect of 
> rebuilding several over the next several months.  I have in the past 
> been fortunate in being able to very successfully clean them without 
> disassembly.  Gummout carb cleaner does wonders for cutting the crud.  
> That and simple green do a great job.  I re-lube with Mobile 1 
> synthetic motor oil in a syringe with the hypo ground flat on the 
> sharp end.  Works great!
>
> I would like to go through one using the disassembly method of 
> cleaning to see if it is really to any advantage.  Even the split 
> gears can be separated enough with a knife blade to blow the carb 
> cleaner in...but I would like to try it the other way and get a good 
> feeling for doing a full resync.
>
> Cecil...
> ----- Original Message ----- From: "Bob Camp" <ham at cq.nu>
> To: "Barry" <N4BUQ at aol.com>; "R-390 HF Receiver List" 
> <r-390 at mailman.qth.net>
> Sent: Thursday, February 24, 2005 5:50 PM
> Subject: Re: [R-390] More geartrain rebuild info
>
>
>> Hi
>>
>> I very much agree that a gear train with a reasonable amount of crud 
>> in it probably will require the planetary gears be torn down. When 
>> you do the only way to really get them clean is to take them down to 
>> pieces and clean each one.
>>
>> The obvious gotcha is how do I get these back together with only two 
>> hands and a limited number of toes involved. Cleverly bent paper 
>> clips seem to be the "other" way to do this if you don't have access 
>> to stuff like plastic hemostats.
>>
>> Here's an issue that's a little more subtle. The gears probably left 
>> the factory all nice and uniform. When they did you could swap any 
>> "top" with any "bottom" and there would be no net effect at all. Over 
>> the years each "top" has rubbed against it's respective "bottom" for 
>> a really long time. Essentially you have created matched pairs of 
>> gear halves.
>>
>> So in addition to needing a number of fingers and toes to put it all 
>> back together you also need three sets of eyes to make sure all the 
>> sets remain with each other.
>>
>> The gear will work pretty darn well even if you randomize the gears. 
>> My story is that it was a controlled experiment and I'm sticking to 
>> it. If you want a silky smooth gear set when you are done it seems to 
>> be best to keep everything in order ....
>>
>> Enjoy!
>>
>> Bob Camp
>> KB8TQ
>>
>>
>>
>> On Feb 23, 2005, at 10:19 PM, Barry wrote:
>>
>>> List,
>>>
>>> In the process of tearing down this geartrain, I noticed the 
>>> planetary gears
>>> were quite clogged with grease.  Scott's slide show says it probably 
>>> isn't
>>> necessary to tear the planetary gears apart, but it didn't appear I 
>>> would
>>> get this one clean unless I did and I'm sure glad I did.
>>>
>>> Upon taking apart the three split gears, all three exhibited a fair 
>>> amount
>>> of drag when I twisted them against each other.  Upon closer 
>>> inspection, I
>>> could see small burrs on the teeth.  After removing these burrs, the 
>>> gears
>>> ride smoothly against each other.  I would never have known this 
>>> unless I
>>> disassembled them.  Also, it gives me a good chance to ensure a lot 
>>> of the
>>> hardened grease and dirt is removed.  After a 24-hour soaking in 
>>> kerosene,
>>> there was still a significant amount of grime in this assembly.
>>>
>>> Now if I can figure out how to get four split gears all tensioned and
>>> reassembled at the same time!
>>>
>>> Barry(III) - N4BUQ
>>>
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