[ARC5] Fwd: [armyradios] Dynamotor brushes

[Clare Owens]

I fumbled the reply...
---------- Forwarded message ----------
From: Clare Owens <clare.owens at gmail.com>
Date: Sun, Mar 30, 2008 at 5:25 PM
Subject: Re: [armyradios] Dynamotor brushes
To: armyradios at yahoogroups.com, milsurplus at mailman.qth.net, arcs at mailman.qth.net


Well, I ended up driving it out.  I tried heating it with my heat gun
 and pressing on it, tapping on it then just drove it out.  Finding
 that I have not 4 but 8 sets of the DM-28 LV brushes plus one extra
 helped me make the decision to drive it.  It's been running for about
 3/4 hour now on my bench and seems to be doing fine.  I searched the
 drawer of #6 screws and found 3 end cap safety wire screws and one
 very similar so I can attach the caps properly.  Not the best looking
 unit but someday it'll be inside a radio where it won't show.

 If anyone is desperate for a set of the LV brushes I could spare a
 couple of sets.

 I have liked to work on small DC motors ever since my father showed me
 how when I was quite young.  I showed our three children and soon
 it'll be time to show the grandchildren.  I have lots more dynamotors
 that could use a tune up after 60+ years.

 Thanks for all of the suggestions.

 Clare  N2RJB



 On Sun, Mar 30, 2008 at 3:11 PM, Brooke Clarke <brooke at pacific.net> wrote:
 >
 >
 >
 >
 >
 >
 > Hi Clare:
 >
 >  I have had good luck using Kroil penetrating oil on metal parts that have
 > been
 >  stuck and it might work here. Sure is worth a try.
 >
 >  Some chemicals that are handy:
 >  http://www.prc68.com/I/FlashlightPat.shtml#CF
 >
 >  Have Fun,
 >
 >  Brooke Clarke
 >  http://www.prc68.com/P/Prod.html Products I make and sell
 >  http://www.prc68.com/Alpha.shtml All my web pages listed based on html name
 >  http://www.PRC68.com
 >  http://www.precisionclock.com
 >  http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam
 >
 >
 >
 >  Clare Owens wrote:
 >  > I'm in the process of fixing up the DM-28 dynamotors I bought at the
 >  > CC-AWA Conference a week ago. One of them was essentially unused and
 >  > the grease softened up nicely with some light oil. It ran fine for
 >  > 1/2 hour last night, no trouble at all. But the other one has seen a
 >  > lot of wear, lots of carbon powder in the housing, rough feeling
 >  > bearings and one LV brush is stuck tight.. Really tight. I have
 >  > removed the LV end bell and while I was cleaning the bearings I
 >  > removed the brush holder and applied motor cleaner then soaked the
 >  > holder in Acetone and now have applied a lot of force in both
 >  > directions with no results except a little chipping. I guess I'll
 >  > have to destroy it to get it out.
 >  >
 >  > The good news is that I just looked in my box of very old brushes and
 >  > I have an envelope of unused spares for all four brushes. The part
 >  > numbers on the envelopes match the parts list numbers for the brushes
 >  > for the DM-28 for the BC-348-H anyway. This one was from an "O" but
 >  > should be the same, no?
 >  >
 >  > But before I destroy this brush, does anybody have any other method to
 > try?
 >  >
 >  > Also this brings up the question: Why are they so specific about the
 >  > positive and negative polarities of the brushes? They have different
 >  > part numbers, there are plus and minus signs molded into the housings,
 >  > etc.
 >  >
 >  > What difference could polarity make in a graphite brush?
 >  >
 >  > Also, I just have to comment on the high quality of design and
 >  > manufacturing of these units. The dynamotor innards I have seen over
 >  > the years all have been remarkable examples of how to build a device
 >  > that would work well under harsh conditions and last for many, many
 >  > years. They make the insides of most of my modern electric tools look
 >  > like junk.
 >  >
 >  > Thanks,
 >  >
 >  > Clare N2RJB