[Public-List] Cleaning the starter motor commutator

[Randy Katz]

Michael, Thanks again for your comment. That rang a bell, so I looked this
up in *Marine Diesel Engines* (3rd ed, the small 2007 book) by Nigel Calder
which I'd recently consulted. I was wondering about sandpaper vs emery or
wet/dry. Here's what he says on p. 79, a bit ambiguously perhaps:


*You can clean the commutator by pulling  strip of fine sandpaper (400- to
600-grit wet-or-dry) lightly back and forth until all of the segments are
uniformly shiny. Cut back the insulation between each segment of the
commutator to just below the level of the copper segments by drawing a
knife or sharp screwdriver across each strip of insulation. Take care not
to scratch the copper or burr its edges...*
I plan to see what I can find in the way of very fine sandpaper...

Thanks,
Randy Katz
Simple Gifts #249
Seattle/Bellingham, WA



*______________________________*

On Sat, Nov 16, 2019 at 4:03 PM Michael Connolly <crufone at comcast.net>
wrote:

> Randy,
> Just to mention.  You spoke of "lightly sanding" the commutators of the
> starter and alternator. Be sure to use "sand" paper.  The use of "emery" or
> "wet/dry" paper will cause issues.  The abrasives on these papers will
> conduct electricity. If polishing debris gets clogged in the insulators
> between the commutator segments they will short out.  It is also a good
> idea to use a narrow tool to carefully run over the recessed insulators to
> remove any material which may bridge over between the segments.
> When shops refurbish armatures they use a lathe to turn the commutators to
> a smooth surface and then use a tiny rotating saw to undercut the
> insulators.
> Michael #133
> > On November 7, 2019 at 8:13 PM Randy Katz via Public-List <
> public-list at lists.alberg30.org> wrote:
> >
> >
> > Greetings, Sailors,
> >
> > I just pulled my starter (with solenoid) and alternator for a check.
> > They're the original equipment on my Universal/Westerbeke M3-20B diesel
> > engine, which was installed about 20 years ago (with 1700 hours now). The
> > parts function well to date, but I wanted to check on them given their
> age.
> >
> > The local Westerbeke sales outlet Gallery Marine in Seattle suggests
> > Ballard Electric for testing these two parts, but I went to *Blanchard
> > Electric near Boeing Field* instead. I'm glad I did!
> >
> > Todd in the Blanchard shop was surprised I'd think servicing was needed,
> > given such "low hours." (It's true, I was looking at an average use of
> 100
> > hrs/year.) However, he said he'd take a look at the brushes on each piece
> > if I used his tools on the spot to take apart the starter and
> alternator. I
> > did, and he showed me how I could read the what part of the brushes were
> > used and what remained. All the brushes on both parts were fine with
> plenty
> > of life remaining. He said if they were his, he'd put them back on the
> > engine and not worry about it. If anything, the solenoid could be
> replaced
> > for < $100, but unless the contacts were wrecked up, that wouldn't be
> > needed. (Easy to check this, said he. I plan to.)
> >
> > *QUESTION*-- Is there anything else that needs to be checked as long as I
> > have the starter & alternator off the boat? Todd thought not.
> >
> > I plan to do basic cleaning, light sanding of the parts that the brushes
> > rub against, and to check that the brushes are still well seated, given
> my
> > fiddling around.
> >
> > Many thanks for any comments~~
> >
> > Randy Katz
> > SImple Gifts #249
> > Seattle/Bellingham
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