[HAM] Noisy upper rotor

[David Anderson]

John,

The plastic horn is fastened to the metal bearing it rotates on with  
two screws.

In two 1950s cabinets I have, the horn is not cast with a pulley on  
it; the pulley is made of some material that I *think* is phenolic,  
though I could be wrong. The metal bearing housing is pressed into  
this pulley. Technically, I suppose the pulley could be removed from  
the bearing, but I haven't attempted it. Maybe someone can comment.

At some point, the plastic horns were changed (to the design that has  
become standard) such that the horn and pulley are all one plastic  
unit that can be completely unscrewed from the metal bearing housing.  
This design is less problematic when it comes to soaking the bearing  
in solvent. These later horns seem to me to be cast of thicker,  
heavier plastic, btw.

This summer, after letting a horn bearing soak for a couple of days,  
I blew compressed air into the oiling hole (with the bearing wrapped  
in paper towels!) I was surprised at how much brown gunk blew out of  
it. It's a good way to experience how "porous" the bearings are. I  
then oiled it and blew more compressed air in: instant thorough  
oiling as the air pressure blew the oil through the pores.

I actually like that thicker honey-like oil Hammond-Suzuki sells as  
"Leslie motor oil" for the horn bearing (but only the horn bearing).  
It seems to stay in the bearing surface better. For the motors  
themselves, I prefer a thinner clear turbine oil. Turbine oil is what  
makers of sintered bronze bearings impregnate the bearings with at  
the factory. The brand of oil I use is sold at the local Grainger as  
"Zoom Spout" turbine oil.

David

On Feb 7, 2008, at 10:52 PM, John Freund wrote:

>> And while you're doing the motors, take the horn rotor bearing, soak
>> it in naphtha or alcohol, let it dry (or blow out with compressed
>> air) and re-oil. However, don't soak the older bearings with the
>> integral pulley.
>
> David -
>
> I want to understand exactly what you mean...are you talking about  
> taking
> the bearing out that's in the HORN (I didn't know you could do  
> that) or the
> spindle bearing that's attached to the driver?
>
> And what is the "integral pulley"?
>
> This must be Everyday because I think I'm about to learn something  
> new.
>
> /John