[R-390] Autotuners

[Michael Murphy]

Ahh the scintillating smell of soaking in circulating sintering solvents!

Mike WB2UID

----- Original Message ----- 
From: "Paul H. Anderson" <paul at pdq.com>
To: "Barry Hauser" <barry at hausernet.com>
Cc: <r-390 at mailman.qth.net>
Sent: Wednesday, January 05, 2005 1:57 PM
Subject: Re: [R-390] Autotuners


>
> My guess on removing them?  If you can get to the back side, like you can
> on the various RF decks, the right size punch will pop them out with no
> trouble at all.  I scavenged a junk 390A RF deck and removed all the
> bearings this way with no damage to them (that I could see) nor to the RF
> deck.  Of course, the RF deck is stainless steel, but my sense was that
> the forces involved were so small, even brittle pot metal wouldn't be a
> problem.
>
> I scavenged the bearings with the intent of seeing if they were the same
> as the ones in the R-391 autotune mechanism line shaft, but I haven't had
> a chance to look that closely yet.
>
> Paul
>
> On Wed, 5 Jan 2005, Barry Hauser wrote:
>
> > 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
> >
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