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Re: [PSUBS-MAILIST] thru hull fittings

To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] thru hull fittings
From: "Brian Cox" <ojaibees@ojai.net>
Date: Sun, 29 Feb 2004 20:27:59 -0800
References: <4371B9E007C62D40A46FA016C2043E5720AFC8@cp_mail.cp.com> <000801c3fdc0$1ff7d670$33d44940@pc> <003c01c3fe01$deef1a20$87603118@FAMILYROOM> <000401c3fe56$470a5d50$33d44940@pc> <000801c3fec6$aa44ef50$87603118@FAMILYROOM> <000401c3fee7$7080de20$37d44940@pc> <000801c3feee$ff251e00$87603118@FAMILYROOM> <000601c3fef5$79322d40$2ad44940@pc> <002c01c3ff01$9d9bf600$923579c3@oemcomputer>
Reply-to: personal_submersibles@psubs.org
Sender: owner-personal_submersibles@psubs.org

Thijs,  
               If I'm not mistaken I think that is what Alec has done.

Brian

----- Original Message ----- 
From: "Thijs Struijs" <thijs-struijs@planet.nl>
To: <personal_submersibles@psubs.org>
Sent: Sunday, February 29, 2004 12:21 PM
Subject: Re: [PSUBS-MAILIST] thru hull fittings


> I just posted a drawing (or at least i hope i did) to Moki files of a thru
> hull fitting. It is just an idea for solving 2 problems: weakening the shaft
> and machining an O-ring grove in the fitting. Maybe it is a solution.
> Have a look at:
>     http://www.prismnet.com/~moki/subfiles.html
> 
> Greatings,
> 
> Thijs Struijs
> The Netherlands
> 
> 
> ----- Original Message -----
> From: "Brian Cox" <ojaibees@ojai.net>
> To: <personal_submersibles@psubs.org>
> Sent: Sunday, February 29, 2004 7:54 PM
> Subject: Re: [PSUBS-MAILIST] thru hull fittings
> 
> 
> > Ok , so if I'm understanding this now the issue here is the strength of
> the shaft.  If that is the only issue I would have to say that it would not
> make any difference whether the o ring is on the shaft or the inside the
> fitting.  Since it would be  much easier to machine a O ring grove in the
> shaft and also easier to inspect for burrs and put chamfer on the edges of
> the grove I submit that putting the O rings on the shaft would be more
> advantages.  If you have to turn that 1/2" shaft hard enough so that it
> would sheer off then there is some other problem. Am I missing something?
> >
> > Brian
> > ----- Original Message -----
> > From: "Dan H." <jmachine@adelphia.net>
> > To: <personal_submersibles@psubs.org>
> > Sent: Sunday, February 29, 2004 10:08 AM
> > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> >
> >
> > > Brian,
> > > No, no Not at all.
> > >
> > > Either O-rings on the shaft, or O-rings in the housing will work.  As
> far as
> > > leaking, it's the shaft to housing clearance and the proper groove depth
> > > that matter.  And yes, hydraulic applications do sometimes use O-rings
> in a
> > > shaft but not as a rule.  If the shaft is the critical component, the
> O-ring
> > > grooves are in the housing.  Grooves in a shaft weaken it.
> > >
> > > Maybe I didn't explain myself well before.  What I meant by my earlier
> > > posting was, if you groove the shaft, the groove diameter, minis a
> little
> > > factored in for the stress risers created by the groove, becomes the
> working
> > > diameter of the shaft.  The weakest point!  A groove does create stress
> > > riser.  If you break a shaft with grooves in it, it will always fail in
> one
> > > corner of a groove.  A properly designed O-ring groove has small radii
> in
> > > it's corners, but still it's a week spot.  If you take the same shaft
> size,
> > > but put the O-ring in the housing, you can design around the full shaft
> > > diameter.
> > >
> > > I tried to keep my shaft diameters from getting larger then needed
> because,
> > > as a shaft get larger it takes more force to turn when your deep. At 400
> > > feet a one inch shaft has 160 pounds of force pushing in on it.  That
> > > creates friction that you have to overcome to turn it.
> > >
> > > Dan H.
> > > ----- Original Message -----
> > > From: "Brian Cox" <ojaibees@ojai.net>
> > > To: <personal_submersibles@psubs.org>
> > > Sent: Sunday, February 29, 2004 12:14 PM
> > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > >
> > >
> > > > Hi Dan,
> > > >                    I knew that would draw a response !  I really don't
> > > follow the reasoning on this.  I simply do not understand what you are
> > > saying.  Don't most hydraulics have the O rings on the the shaft and
> with
> > > those we're talking 3000 psi.  If I had the O rings on the shaft are you
> > > saying that I would not be able to turn the shaft?  And the O ring would
> > > leak because there is more stress on the corners of the O ring grooves?
> I
> > > don't get it !  Sorry to be so difficult and annoying !
> > > >
> > > > Brian
> > > > ----- Original Message -----
> > > > From: "Dan H." <jmachine@adelphia.net>
> > > > To: <personal_submersibles@psubs.org>
> > > > Sent: Sunday, February 29, 2004 5:19 AM
> > > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > > >
> > > >
> > > > > Brian,
> > > > > O-rings on the shaft create areas of higher stress in the corners of
> the
> > > > > O-ring grooves.  Also your shaft diameter is the area that the sea
> is
> > > acting
> > > > > on when calculating how much force is pushing inward on the shaft.
> At
> > > depth
> > > > > that force creates some resistance to turning.  But, for sheer,
> tension
> > > and
> > > > > compression, your shaft diameter is only the root to the O-ring
> groove
> > > minus
> > > > > a bit for the stress risers in the groove corners.
> > > > >
> > > > > It's a bit more difficult putting the O-rings in the thru hull, but
> the
> > > > > shaft in one size and most efficient.
> > > > >
> > > > > Dan H.
> > > > > ----- Original Message -----
> > > > > From: "Brian Cox" <ojaibees@ojai.net>
> > > > > To: <personal_submersibles@psubs.org>
> > > > > Sent: Saturday, February 28, 2004 6:54 PM
> > > > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > > > >
> > > > >
> > > > > > Dan,  thanks for the insite,  I'll probably go bigger on the drop
> > > weight.
> > > > > My "O" rings are going to be on the shaft.
> > > > > >
> > > > > > Brian
> > > > > > ----- Original Message -----
> > > > > > From: "Dan H." <jmachine@adelphia.net>
> > > > > > To: <personal_submersibles@psubs.org>
> > > > > > Sent: Saturday, February 28, 2004 5:50 AM
> > > > > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > > > > >
> > > > > >
> > > > > > > Brian,
> > > > > > >
> > > > > > > You sound like your on the right track with your through hulls.
> One
> > > > > thing
> > > > > > > to consider with your drop weight through hulls is, how your
> going
> > > to
> > > > > attach
> > > > > > > the handle inside the sub.  If your going to drill through the
> shaft
> > > you
> > > > > may
> > > > > > > want to consider a shaft larger then a half inch since it's
> holding
> > > the
> > > > > drop
> > > > > > > weight and will get yanked through the hull if it breaks or of
> the
> > > bolt
> > > > > > > shears.  When making mine, I was visualizing the drop banging up
> and
> > > > > down on
> > > > > > > it's shaft while tailoring down the road.  Then I want to depend
> it
> > > to
> > > > > hold
> > > > > > > the weight when diving.
> > > > > > >
> > > > > > > I had a bit of trouble with the through hulls necking down in
> the
> > > weld
> > > > > area
> > > > > > > but cured the problem with a hand reamer after welding.  Use two
> > > > > O-rings,
> > > > > > > one near each end, for double protection and then you won't be
> > > welding
> > > > > or
> > > > > > > reaming where they will be.
> > > > > > >
> > > > > > > Dan H.
> > > > > > >
> > > > > > >
> > > > > > > ----- Original Message -----
> > > > > > > From: "Brian Cox" <ojaibees@ojai.net>
> > > > > > > To: <personal_submersibles@psubs.org>
> > > > > > > Sent: Saturday, February 28, 2004 1:00 AM
> > > > > > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > > > > > >
> > > > > > >
> > > > > > > > Alec,   If I'm envisioning that piece correctly it started out
> as
> > > a
> > > > > 1.5"
> > > > > > > dia shaft and a portion was machined down to 1" , then the part
> is
> > > > > inserted
> > > > > > > from the outside of the sub where the  lip keeps the part from
> > > blowing
> > > > > into
> > > > > > > the sub under pressure.  I probably don't have your dimensions
> quite
> > > > > right
> > > > > > > but I think I see the part.  Are the shaft and hole 1"  +/-  2
> > > > > thousandths?
> > > > > > > >
> > > > > > > > Brian
> > > > > > > > ----- Original Message -----
> > > > > > > > From: "Alec Smyth" <Asmyth@changepoint.com>
> > > > > > > > To: <personal_submersibles@psubs.org>
> > > > > > > > Sent: Friday, February 27, 2004 4:28 PM
> > > > > > > > Subject: RE: [PSUBS-MAILIST] thru hull fittings
> > > > > > > >
> > > > > > > >
> > > > > > > > > Yes, there's a reason. Because the sub is hydrobatic, when
> the
> > > sub
> > > > > is at
> > > > > > > a 90 degree roll the drop weight will exert a bending moment. So
> I
> > > made
> > > > > it
> > > > > > > stubby. The maximum diameter is 1.5", and its set in an insert
> that
> > > is
> > > > > 3" in
> > > > > > > diameter. The difference between the diameters of the shaft and
> the
> > > hole
> > > > > is
> > > > > > > only 2 thousandths of an inch, so that the O rings cannot
> extrude
> > > and so
> > > > > the
> > > > > > > insert will help the shaft resist the bending moment. And the
> reason
> > > I
> > > > > said
> > > > > > > "maximum diameter" is that there is a 1" section on the shaft
> too,
> > > to
> > > > > > > prevent the ambient pressure from shooting it into the boat
> after
> > > > > releasing
> > > > > > > the drop weight, or when the sub is inverted.
> > > > > > > > >
> > > > > > > > > Sorry for writing a book on such a small topic...
> > > > > > > > >
> > > > > > > > > Alec
> > > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: Brian Cox [mailto:ojaibees@ojai.net]
> > > > > > > > > Sent: Fri 2/27/2004 5:40 PM
> > > > > > > > > To: personal_submersibles@psubs.org
> > > > > > > > > Cc:
> > > > > > > > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Thanks Alec,   I read a few posts back that your drop weight
> > > shaft
> > > > > was
> > > > > > > like 2" or something,  it seamed rather large was there some
> reason
> > > for
> > > > > > > that?
> > > > > > > > >
> > > > > > > > > Brian
> > > > > > > > > ----- Original Message -----
> > > > > > > > > From: "Alec Smyth" <Asmyth@changepoint.com>
> > > > > > > > > To: <personal_submersibles@psubs.org>
> > > > > > > > > Sent: Friday, February 27, 2004 1:28 PM
> > > > > > > > > Subject: RE: [PSUBS-MAILIST] thru hull fittings
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > > With a 1.25" insert, you have added much more
> reinforcement
> > > than
> > > > > the
> > > > > > > material you removed with a 0.5" shaft hole. If I remember
> right,
> > > the
> > > > > rule
> > > > > > > of thumb is that you should add twice as much as the hole
> removed.
> > > So it
> > > > > > > should be sufficient.
> > > > > > > > > >
> > > > > > > > > > Alec
> > > > > > > > > >
> > > > > > > > > > -----Original Message-----
> > > > > > > > > > From: Brian Cox [mailto:ojaibees@ojai.net]
> > > > > > > > > > Sent: Fri 2/27/2004 3:51 PM
> > > > > > > > > > To: Personal_Submersibles@psubs.org
> > > > > > > > > > Cc:
> > > > > > > > > > Subject: [PSUBS-MAILIST] thru hull fittings
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Hi All,    I am in the process of machining thru hull
> fittings
> > > > > (316L
> > > > > > > ss) that will have 1/2" shafts running through them to turn
> valves,
> > > turn
> > > > > > > rudders, and other functions as well, drop weight, and possibly
> move
> > > > > trim
> > > > > > > ballast ;-)     .  The fittings that I am machining at the
> moment
> > > are 1
> > > > > 1/4"
> > > > > > > od  with the 1/2" id ( for the shaft)  is that 1 1/4"  a big
> enough
> > > > > chunk of
> > > > > > > steel to be welded through 1/4" A516 70   or should that OD be
> > > larger
> > > > > for
> > > > > > > some reason?
> > > > > > > > > >
> > > > > > > > > > Thank You
> > > > > > > > > >
> > > > > > > > > > Brian Cox
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> > >
> >
> > ================================================================
> > Deze e-mail is door E-mail VirusScanner van Planet Internet gecontroleerd
> op virussen.
> > Op http://www.planet.nl/evs staat een verwijzing naar de actuele lijst
> waar op wordt gecontroleerd.
> >
> 
>

References:
- RE: [PSUBS-MAILIST] thru hull fittings
  - From: "Alec Smyth" <Asmyth@changepoint.com>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Brian Cox" <ojaibees@ojai.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Dan H." <jmachine@adelphia.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Brian Cox" <ojaibees@ojai.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Dan H." <jmachine@adelphia.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Brian Cox" <ojaibees@ojai.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Dan H." <jmachine@adelphia.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Brian Cox" <ojaibees@ojai.net>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: Thijs Struijs <thijs-struijs@planet.nl>

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