Re: [CAD_CAM_EDM_DRO] Re: Bridgeport servo motors

right Dennis, except some armatures have the poles turned to favor one
direction. very hard to get them to run the same in both directions. I tried
to reverse a Bodine Motor for a spindle motor, the brushes lasted 20 hours
till gone. unless i change the iron on the rotor and rewind it will always
go in one direction. cul brian f.

----- Original Message -----
From: "Denis Casserly" <denisc@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, February 05, 2005 2:00 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Bridgeport servo motors


>
> Re the brush angle
> I could be wrong, been out of school for a long time, but
> the brushes might be placed at this angle in order to reduce the affects
of
> armature reaction which is an 'S' shaped distortion of the main field flux
> due to current flowing in the field windings. Armature reaction varies
> directly with the current flowing through the field windings and causes
the
> nuetral plane of the brushes to shift in the same direction as the
rotating
> armature. The motor will rotate in the opposite direction but there will
be
> excessive sparking at the brushes, the commutator will take a real
beating,
> and the output power will be reduced. The brush angle may have been
shifted
> optimally away from the nuetral plane so that the motor application will
> handle a constant load in that rotation direction and also deliver maximum
> power, because the affects of armature reaction also impact slightly on
> output power.
> If you were to remove the end bell and shift the brushes back to the
nuetral
> plane you might find it would deliver the same performance in both
directions
> with minimum sparking.
> cheers,
> Denis Casserly
>
>
> On February 4, 2005 10:44 pm, Jon Elson wrote:
> > braidmeister wrote:
> > >Scott,
> > >Unfortunately...It is correct...they ARE CCW...#$^%^(*()&$!!!!
> > >
> > >I just called them and the tech opened up the motor and looked at the
> > >brushes. He said that it did sound different running it forwards or
> > >backwards...BUT the brushes were angled...and there is no easy way to
> > >get them timed for both directs.
> > >
> > >WHAT A HUGE DISAPPOINTMENT!!!
> > >
> > >So now...back to freakin' square 1. I would be interested in other
> > >types of motors than these or the Ameteks (too slow). Anybody got a
> > >source for 3 that will work at a decent price? (Decent meaning better
> > >than $400 ea)
> > >
> > >SO here's a question for you people: Since Surplus Center advertised
> > >the motors as bi-directional, who pays for the shipping up and back?
> > >Why should I have to pay shipping on something that was falsely
> > >advertised?
> >
> > No doubt the brushes are run in in one direction, due to the intended
use
> > of the motors. But, that doesn't mean they CAN'T be run the other
> > direction.
> > You might have slightly faster brush wear with this setup, but it may be
> > almost
> > insignificant. If you run it both directions, the brushes will likely
> > change their
> > fit slightly, and the difference in sound will stop. It might be a good
> > idea to adjust
> > the brush holders (I'm guessing these are cheaply made motors, with
stamped
> > brass brush holders riveted to a phenolic card or something similar.)
> > If the
> > brushes rock in the holders when you reverse direction, this will make
> > for poor
> > fit between the brush and commutator, So, you might want to make sure
> > the brush holders grip the sides of the brush well enough to minimize
the
> > rocking. Other than that, they most likely will work OK.
> >
> > As for return, if you lean on them, they might agree to a UPS "call tag"
> > where they pay the shipping to return the items. You've probably got a
> > couple days to research it and see if anyone is using them in reversing
> > operation
> > without trouble.
> >
> > Why are the Ameteks too slow? Given a suitable power supply, I think
> > they can
> > do OK.
> >
> > Jon
> >
> >
> >
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aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
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> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
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> List Mom
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