[R-390] Autotuners

[Barry Hauser]

Hi Bill & list:

I don't know how practical it would be to apply a vacuum -- don't exactly
have a vacuum pump on hand.  It may be that penetrating oil -- which has
solvent mixed in -- would leach into the bronze sufficient to replenish.
However, that oil might be too thin.

May well be that the bearing is typically too worn by the time the oil is
spent.  They still make a wide assortment of these bearings and the correct
size -- inside & outside diameter could be found.  The existing ones are
pressed into or glued into the casting and possibly peened over a bit.  They
are mostly (4 or 5 of them) mounted in small, fragile protrusions.  The
casting is aluminum, aluminum alloy or pot metal and probably fairly
brittle.  The geometry is such that I doubt if they can be pressed out on a
standard arbor press.  There are other approaches to removing them, but
anything involving impact -- hammer blows, etc. -- would be dicey.  Might
have to be drilled through and ground out with a Dremel or something.
Similar approach that modern dental surgeons use in extracting big molars
<ugh>.  They drill through the bifurcation (junction of roots in the base),
breaking it up into 3 or 4 pieces in the jaw, then extract each separately
to minimize trauma to the gum and jawbone socket.  (Aren't you all glad you
read this far?)

It would be a piece of work.

Barry



Bill Hawkins wrote,
>
> Sintered bronze is porous, but you can't relube it by soaking. You need to
> pull a vacuum on it while it sits in a jar of light oil. But first you
have
> to clean the old, gummy oil from the pores with the usual solvents and
> vacuum, then heat to evaporate the solvent.
>
> OTOH, soaking the bearing in solvent, heating it a bit (no smoke!) and
then
> soaking it in, say, 3-in-1 oil will work for a while. The problem with
> soaking
> in air is that the air in the pores is not displaced, so not much can soak
> in.


> Barry Hauser wrote,
>
> "The worm drive goes through several sintered bronze Oilite bearings.  The
se
> are porous bronze bushings that were permanently lubricated.  But,
> "permanent" generally assumes for the "life of the tool" or whatever, not
> necessarily 50 years going on another 50.  Those bearings were pre-soaked
in
> a special lubricant -- but I don't know what."