[R-390] Planetary Gear Assembly

[Barry]

Yeah, I had problems counting teeth too, especially with the halves apart
like that.  I think I got at least 2 teeth loaded on each one, though.  I'm
figuring that with three gears, a small amount of anti-backlash tension on
each one is sufficient - especially considering how soft those brass gears
are.

Interesting idea of the solder.  As I said, though, with pre-tension on the
planetary gears, I could never get them together without something
mis-aligned; however, given the mechanics involved, I could never figure out
what was causing the "crookedness" I was seeing.  It was so bad that the
whole assembly would not slide onto the shaft.  The pressed gears in the
"front" would be cocked to one side and I just couldn't figure out what was
causing it.  My new method (while a bit tricky) did work great.

I have a broken bandswitch clamp that I need to get a replacement for;
however, once I get that, I can't wait to get this back together and see how
much difference I can feel between this one and my first one which I did not
tear down.  If there's a lot, then it looks like I have one more job to do!

Thanks,

Barry(III) - N4BUQ

----- Original Message ----- 
From: "John KA1XC" <tetrode at comcast.net>
To: "R-390 reflector" <r-390 at mailman.qth.net>
Sent: Monday, March 07, 2005 10:04 AM
Subject: Re: [R-390] Planetary Gear Assembly


> Interesting technique. You know, the springs in those planetary gears are
so
> weak I'm never sure when to actually start counting the gear teeth when
> loading them. I've never used hemostats for holding any of the other split
> gears together, a small screwdriver blade always worked fine for me. Maybe
> I'll try it next time.
>
> For holding the planetary gears I've always used plain old solder; wrap a
> couple of inches or so of  it around the tensioned gear front to back so
as
> to engage the teeth and then finger twist it tight. Because the solder is
> soft it mushes into and around the gear teeth nice and close. Then after
the
> whole thing is assembled just snip the solder loose. Some folks use solid
> hookup wire too.
>
> John
>
>
> ----- Original Message ----- 
> From: "Barry" <N4BUQ at aol.com>
> To: <r-390 at mailman.qth.net>
> Sent: Sunday, March 06, 2005 9:39 PM
> Subject: [R-390] Planetary Gear Assembly
>
>
> > Just thought I'd pass along a tip.  When I tried to reassamble the three
> > planetary gears to their mating gears, I could never get them to go
> together
> > without something going wrong.  Preloading the anti-backlish gears and
> > holding them with hemostats just wouldn't work.  The assembly would bind
> and
> > be misaligned.  I never did figure out what caused this, but I did
figure
> > out a way to successfully reassamble them.
> >
> > The method I used was to assemble the planetary gears without the clip
> that
> > holds the anti-backlash gear in place.  The assembly will go together
> quite
> > easily this way and there is room for the anti-backlash gears to move
out
> of
> > the way slightly so that they don't interfere in this first step.  Of
> > course, you pre-load the anti-backlash gear in the center at this point
as
> > it can't be done later.
> >
> > After tightening the three screws that hold the planetary gear shafts,
you
> > can then load each anti-backlash gear, one at a time.  There is
sufficient
> > clearance just above the center gear to allow this.  It's a bit tricky
to
> > get both nibs of the internal spring into their respective holes in each
> > half of the gear, but it can be done.  With the anti-backlash gear
cocked
> > just a bit to clear the mating gear, you can put a few teeth of spring
> load
> > on the anti-backlash gear half and then let it slide down onto the
mating
> > gear.  Press the "C" clip in place and proceed to the next gear.  It
> really
> > worked out rather easily.
> >
> > AND, if you want some real fun, take a toothbrush and some Brasso(tm) to
> > that big brass gear assembly that is comprised of two larger gears that
> are
> > riveted together.  Wow.  Does that thing ever shine up nicely!  Yeah, I
> know
> > it won't work any better shiny than dull, but there's just something
about
> a
> > sparkly gear that satisfies my R390A rebuilding soul.
> >
> > Happy rebuilding,
> >
> > Barry(III) - N4BUQ
> >
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