[Boatanchors] [Milsurplus] vintage motor winding question

[J. Forster]

I looked at you pic and could not see any breaks in the lamination.

Because of the construction it will be nearly impossible to rewind the
coil w/o drilling out the rivits. And, if you do drill them, I suspect it
will be pretty hard to reassemble the thing properly.

My *guess* is that cutting off the existing winding and replacing it with
something like #18 to #20, hand wound, and using a transformer would be
your best shot.

Good luck!

-John

====================






> Actually, here's how the laminations look on one side:
> ||          ||
> =========== =======
> ===================
> =========== =======
> ===================
> =========== =======
> ===================
>  ||<-rivit-> ||
>
> On the other side they look like:
> ||          ||
> ===================
> =========== =======
> ===================
> =========== =======
> ===================
> =========== =======
> ||<-rivit-> ||
>
> If you look at that top lamination's gap, then run your eyes all around
> the motor, looking at that same lam with a magnifying glass, you arrive
> back at the same gap without seeing another one. IOW, it appears each
> lamination is a single plate with only a slit in it at one point. But that
> would be nigh impossible to manufacture. They wouldn't have been able to
> thread them through the winding bobbin.
>
> Wayne
>  WB4OGM
>
>
>
>
>
> -----Original Message-----
> From: J. Forster <jfor at quikus.com>
> To: hwhall <hwhall at compuserve.com>
> Cc: milsurplus <milsurplus at mailman.qth.net>; boatanchors
> <boatanchors at mailman.qth.net>
> Sent: Wed, Sep 18, 2013 4:08 pm
> Subject: Re: [Milsurplus] vintage motor winding question
>
> OK. I would GUESS the laminations are interleaved:
>
>   ||          ||
> =========== =======
> ===== =============
> =========== =======
> ===== =============
> =========== =======
> ===== =============
>   ||<-rivit-> ||
>
> If you remove the rivets, you can probably pull the laminations out
> one-at-a-time, unless the shading coils exclude that.
>
> Some possibilities:
>
> Strip the winding and rewind it using a circular bobbin, like a torroid
> winding machine.
>
> Strip thye winding and rewind w/ something like #22 which is easier to
> handle and will have FAR fewer turns, then put a step-down transformer in
> between the line and motor. This approach will take some calculation, but
> it's not complex. Basically you are 'converting' the motor from 115VAC to
> some lower voltage at a higher current. I's pick winding parameters so a
> 6VAC filament transformer is correct, because they are common as dirt.
>
> Running it w/ reduced turns is asking for trouble, IMNSHO.
>
> -John
>
> ==============
>
>
>
>
> > Yes, it is an AC motor and the frame is like you described it.
> >
> > I'd be willing to rewind from scratch if I could pull the bobbin, but
> the
> > stator frame is riveted together. In the frame at either end of the
> > winding bobbin, I can see gaps in each lamination, but only one per
> > lamination (I've looked all over the frame for other gaps), and they
> > alternate. I.e., the top lam shows a gap on the left side, the next
> lam
> > shows a gap on the right, etc. So, I cannot see how they assembled it
> in
> > the first place, or how I might pull the frame apart to remove the
> bobbin.
> > Unless the "missing gaps" are hidden under the winding bobbin.
> >
> > I've peeled 200 turns off & seem to be past the worst damage. I'm
> thinking
> > I might be able to use a solenoid coil like a motor "growler". If I
> can
> > put a mag field into the frame, a shorted turn might show by causing
> a
> > hacksaw blade to vibrate if touched to the frame. At least, something
> like
> > that is the theory for a real growler in a motor repair shop.
> >
> > We may be able to locate another motor, but they are a limited
> commodity
> > as you can appreciate. If we can learn to fix one, we may one day
> save a
> > few more.
> >
> > 73,
> >
> > Wayne
> >      WB4OGM
> >
> >  -----Original Message-----
> >
> > From: J. Forster <jfor at quikus.com>
> > To: hwhall <hwhall at compuserve.com>
> > Cc: milsurplus <milsurplus at mailman.qth.net>; boatanchors
> > <boatanchors at mailman.qth.net>
> > Sent: Wed, Sep 18, 2013 2:07 pm
> > Subject: Re: [Milsurplus] vintage motor winding question
> >
> > I assume this is an AC motor? Is the winding basically a solenoid on
> a "C"
> > shaped, laminated iron, core, with the motor armature in the gap of
> the
> > "C"?
> >
> > Actually, it doesn't matter that much what the structure is. If a
> winding
> > is burnt, it's finished.
> >
> > What happens is a few turns touch, the insulation fails, and you get
> > shorted turns.
> >
> > The shorted turns act like a shorted transformer secondary and heat
> up.
> > This promotes more failures and pretty soon the whole thing is toast.
> >
> > Aside: I've seen shorted turns causing a winding to glow dull red.
> >
> > Strip it all off and start new, IMO.
> >
> > -John
> >
> > ===============
> >
> >
> >
> >
> > >  Hope this is not too far off topic.
> > >
> > > While working on a Link Trainer restoration, the winding on a
> simple
> > small
> > > shaded-pole motor went up in smoke. It's 1940-ish vintage and
> > resembles
> > > the traditional record-player motor or small desk fan motor.
> However,
> > it
> > > is not easily replaced by a modern motor due to parts of a gear
> train
> > > being mounted on it. I'm peeling off turns hoping the damage is
> in
> > top
> > > layers and a partial rewind may repair it.
> > >
> > > My question is, when I think I've gotten past the burnt turns,
> and
> > have DC
> > > continuity through the winding again, is there a way to detect
> > whether
> > > there may be any shorted turns in the remaining part of the
> winding?
> > All I
> > > can think of right now is to see if it overheats rapidly. Is
> there
> > > anything else to look for?
> > >
> > > TNX & 73,
> > >
> > > Wayne
> > > WB4OGM
> > >
> > >
> > >
> > > ______________________________________________________________
> > > Milsurplus mailing list
> > > Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> > > Help: http://mailman.qth.net/mmfaq.htm
> > > Post: mailto:Milsurplus at mailman.qth.net
> > >
> > > This list hosted by: http://www.qsl.net
> > > Please help support this email list:
> http://www.qsl.net/donate.html
> > >
> > >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>
>