Re: [PSUBS-MAILIST] motor seals

["D. Blake" <dblake@bright.net>]

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
>