[R-390] Ultrasonic cleaning

[rbethman]

I have flown R/C aircraft for a decade or two.  I've rebuilt more 
engines than I can remember.

I'll add that R/C helicopters is in this mix also!

The aluminum or whatever the base metal of engines that come out of 
China discolors the most.

Burnt on castor oil is a pain to get off!

Either Boca or RC Bearings are excellent sources!  Ever single bushing 
on R/C cars or the Helicopters were immediately replaced with Boca Bearings!

I'd have to say that the RPM of the R/C cars exceeded that of the 
aircraft.  When you use electric motors and get into the very fine pitch 
gears, and ceramic clutches, hit speeds on a junker that exceeds 60mph, 
(Real Speed - NOT scale speed!), then the RPMs are really up there.  
Racing the cars on an oval banked track and hitting 90mph real speed, 
you KNOW the entire gear system and motors are beyond the 25K RPM.

The most brutal are the drag racers!  A 1/10th scale rail that goes 
through a 1/10th scale 1/4 mile speed trap that end up in the real speed 
arena of 132mph puts stresses on things that folks can't imagine.

This is why my experience of "observation" of others using a very strong 
ultrasonic cleaner on bearings has led me to my conclusion. All SS 
bearings are one thing.  These in the R-390A gear train do not appear to 
me to be all SS.  I see brass.  That gets me concerned.  Even if only 
the inner and outer races are brass, they will take a beating.

My $0.02 worth!

Never lost a Boca bearing that was properly taken care of!

Bob - N0DGN


On 7/31/2014 12:20 PM, barry williams wrote:
> I fly model airplanes and do a lot of engine work on them. My buddies 
> would laugh at worrying over bearings in an ultrasonic cleaner. We buy 
> them from either Boca or RC Bearings. They run at speeds up to 15,000 
> rpm for sport flying, and about 25,000 rpm for racing.
>
> My cleaner uses plain old water. I do put in a little dishwashing 
> detergent just to cut through burn on castor oil better. I don't know 
> if that helps or not, to tell the truth.
>
> The best method for all metals is to use an old crock pot outdoors on 
> low heat. Put your gears in the crockpot, cover them with antifreeze 
> and come back in about 3 hours. I don't know if that's long enough for 
> just gear gunk but it may be. For burnt on castor and other lubricants 
> we usually go for 8 to 12 hours on engine parts. We have to be careful 
> because a lot of the engine is aluminum and it discolors easily.
>
> the other Barry
>
>
>> It is dependent upon the "strength" of the ultrasonic bath itself.
>>
>> The stronger the movement, the more things will essentially *beat* 
>> against each other.
>>
>> That is the reason I brought up the issue of bearings.
>>
>> During the period that they are in this cleaning solution, the 
>> lubricant WILL be removed.
>>
>> A bearing is either a ball, roller, or needle type of construction.
>>
>> Once the lubricant is gone, then the balls, rollers, or needles will 
>> be vibrating against each other, the cage if such is used, and the 
>> inner and outer races.
>>
>> The result WILL be something that has an significantly increased 
>> clearance than it started with.
>>
>> At that point, you would be *much* better off with simply getting the 
>> sizes, dimensions, and clearances *before* they go into the 
>> ultrasonic cleaner.
>>
>> The reason is simple.  You *WILL* be trying to order new ones from an 
>> outfit such as Boca Bearings.
>>
>> If your numbers do NOT match what is off the shelf, then they will 
>> have to make "custom" ones to fill your order.
>>
>> Custom anything results in the moniker - "BOHICA".  Interpreted, 
>> "Bend Over Here It Comes Again".
>>
>> Bob - N0DGN