[R-390] Cam Pins

[bavarianradio at comcast.net]

Hi Tisha, Yes, I'll be changing the ultrasonic fluid right after this job for sure!! What a mess... You're right, putting something even partially assembled in the tank gives me the creeps, but as I said previously, there's virtually no torque and no constant motion like we see in clock movements. I was taught that EVERYTHING must be disassembled before cleaning, and it sounds like I did way more disassembly than R-390 folks are accustomed to, But I take clock movements apart on a daily basis and am confident about reassembly (especially since I have another one here to look at) I need to put an E. Howard banjo clock back together before I can play with the 390 deck again, So it's off to the clock bench for now. Thanks to everyone on the list here for your support!! 73's Ross W1EKG
----- "Tisha Hayes" <tisha.hayes at gmail.com> wrote:

Quote:
"After 3 hours and releasing only 1 lousy taper pin from the cams, I
studied
the beast again and realized that with much less trepidation, I may be
able
to unbolt the front and rear plates from the chassis and clean the
mechanical elements without the electrical chassis. I was able to do
this
and satisfy my need to "clean" the bearings. I was able to get most of
it in
the ultrasonic cleaner and work it with steel wool pads and brushes. In
doing this, I was able to move the bearings toward the center and
clean/polish the actual bearing surfaces on the shafts.As a bonus, the
brass
parts are also shiny and clean as well. I have been photographing this
operation and will have a link to the photos when I get finished (about
July, I'm guessing hihi) Thanks for all of your support and ideas, 73's
Ross
W1EKG""
I imagine that even the cleanest looking geartrain will leave a bunch of
gunk behind in an ultrasonic cleaner tank after that baptism. As you do
clockworks there probably is a big urge to get in there and make those
bushings, bearings and shafts spotless.
Thank goodness for shaft clamps. At least we are not sitting there with
little files, trying to remove the set-screw burr. I had a older piece
of
gear where someone decided to use a hammer to drift the burred up shaft
through a brass bushing.
Measuring geartrain drag is so subjective. I am surprised that someone
has
not made a jig using a spring tension scale to measure the force.
Those miniature bearings on the ends of the slug racks look suspicious
to
me. It is not as if they are running on a mirror smooth, finished
surface
(same with the cams) When you add up a half dozen of those things, gear
backlash, slight misalignments, dirt and maybe corrosion in a bushing
there
ends up being drag.
I went through that with an SP-600 and it was amazing how smooth the
tuning
became. I stopped just short of taking the cad-plated front panel and
pressing out the bushings and putting in something synthetic like
teflon.