Re: [PSUBS-MAILIST] motor seals

["Gary R. Boucher" <protek@shreve.net>]

     I think that sometimes with pumps the impellers are magnetic in which 
case the unbalanced condition could exist.  Is that what you are referring 
to?  The prop would have to be on a shaft that had bearings for support.

GB

At 09:37 AM 8/16/00 , you wrote:
>Wade, Gary, and All:
>After reviewing a little info on this type of coupling, I noticed a concern
>with "vibtation" and "centering" from the manufacturer.  These are areas to
>be overcome by thoughtful design.  The prop assembly would have to be
>located in such a way as to maintain center to avoid vibration. Another
>thing I thought I would mention is that the shafts on these motors can be
>pressed out and replaced very easily.  I bulit them for years while working
>in a motor factory.  The shaft bodies are knurled, and then pressed into the
>armature.  If need be, a custom shaft could be easily machined on a small
>lathe that would better utilize thrust bearings, allow necessary length for
>the coupling, and provide the possibility for improvement in outside
>housing/endcaps, etc.  Of course this implies practically creating a
>thruster from scratch using only the 'guts' from an existing motor, but it
>sure would be a great addition to a psub!
>Big Dave
>-----Original Message-----
>From: Wade Carson <wacarson@interchange.ubc.ca>
>To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
>Date: Wednesday, August 16, 2000 10:02 AM
>Subject: RE: [PSUBS-MAILIST] motor seals
>
>
> >Gary,
> >Would the magnets be effective enough in shear to maintain a useful
> >coupling?  I have no knowledge or experience in this area, but I do know
>the
> >easiest way to get two magnets apart is to slide them sideways.
> >
> >Wade
> >
> >-----Original Message-----
> >From: owner-personal_submersibles@psubs.org
> >[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Gary R.
> >Boucher
> >Sent: Wednesday, August 16, 2000 9:14 AM
> >To: personal_submersibles@psubs.org
> >Subject: Re: [PSUBS-MAILIST] motor seals
> >
> >
> >Jon,
> >     This is true.  With the exception that you can not load some motors
> >with large forces trying to push or pull on the shaft.  This would require
> >a thrust bearing.  Check out my post on using a tubular geometry to house
> >the magnets.  A metal "Cup" could be placed around an acrylic tube.  The
> >cup could be attched to drive the prop.  This configuration would place no
> >such load on the motor allowing many different types to be used.  The Cup
> >can have two or more magnets inside and it can be metal since it rotates
> >with the inside rotating system of magnets.  Ideally the cup could have
> >blades radiating out used more as a fan than a conventional propeller.  The
> >problem here is building the fan which is beyond the scope of most, me
> >included.  I think it could be easily adapted to a standard propeller
> >however.
> >
> >GB
> >
> >At 07:04 AM 8/16/00 , you wrote:
> >>On Wed, 16 Aug 2000 08:54:19 -0700, "Gary R. Boucher" <protek@shreve.net>
> >>wrote:
> >>
> >> >      The trolling motor shaft has a seal but it would not be necessary
> >in
> >> > this system.  The trolling motor would have on its shaft two magnets
> >> > mounted say one to three inches from the center of rotation, sort of
> >> like a
> >> > "T" with the magnets on the ends of the top of the "T" if that makes
> >> > sense.
> >>
> >>Note also that if you decide to go with a magnetic coupling, you are no
> >>longer stuck with using trolling motors. You can use pretty much any kind
> >>of motor you want... Of course, you'll have to do something for a
> >>propeller, but it shouldn't be too hard to find or make one.
> >>
> >>Later,
> >>Jon
> >>
> >>--------------------------------------------------------------
> >>    Jon Hylands      Jon@huv.com      http://www.huv.com/jon
> >>
> >>   Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
> >>            http://www.huv.com
> >