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Re: [PSUBS-MAILIST] thru hull fittings

To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] thru hull fittings
From: Thijs Struijs <thijs-struijs@planet.nl>
Date: Tue, 02 Mar 2004 20:43:35 +0100
References: <4371B9E007C62D40A46FA016C2043E570334ECDC@cp_mail.cp.com> <003401c3ffd2$4f0ef060$a13479c3@oemcomputer> <000c01c40000$323f5d70$87603118@FAMILYROOM>
Reply-to: personal_submersibles@psubs.org
Sender: owner-personal_submersibles@psubs.org
Thank you Dan and Warren.

Thijs


----- Original Message -----
From: "Dan H." <jmachine@adelphia.net>
To: <personal_submersibles@psubs.org>
Sent: Tuesday, March 02, 2004 3:43 AM
Subject: Re: [PSUBS-MAILIST] thru hull fittings


> Thijs,
>
> Measuring an internal groove is difficult but it's not that difficult to
> machine.  I put internal grooves in all my thru hulls.  Some were as small
> .625 inch shaft diameter.  I put one O-ring in each end of my thru hull
for
> a double seal.  That's the way Kittredge has it on his K-250 and K-350
> plans.  All it take is a lathe and a tool ground to cut the internal
groove
> width you want.
>
> Once you finish the bore to the finished diameter, put the internal
grooving
> tool in the lathe.  Crank it into the bore to where you want the groove.
> With the lathe turning, crank the compound out until it just touches the
> wall of the internal bore.  Now you know where the tool is.  In my case,
at
> .625 diameter.  Now, with the lathe still turning, crank the cross slide
out
> to the diameter of the root of the groove, and that's that.
>
> There isn't any real need to measure the finish groove if you follow that
> procedure.  If your still not sure of yourself, make a test piece.  Make
it
> the same way I described for the groove, only instead of putting the tool
> way in the bore, cut your test as an internal shoulder where you can
easily
> measure the diameter you get.  When you have what you want, go farther in
> the bore and make your groove cranking in the same amount with the cross
> slide as you did for your test.
>
> The tolerance of the groove isn't as critical as the annular clearance,
> between the shaft and thru hull.  If your a few thousands either way, an
> O-ring will still seal fine.  The larger the O-rings cross section the
more
> forgiving the groove tolerance.  A  .139 cross section ring is a good size
> to use.  Not to big, and yet if your four thousands of an inch this way or
> that, it will still work fine.  The groove length is even less critical
but
> be sure you have room for the squeezed O-ring to push into.  Follow the
> chart for the dimensions.
>
> Sorry, I see I got a bit wordy and I apologize.  :-()
>
> Dan H.
>
> ----- Original Message -----
> From: "Thijs Struijs" <thijs-struijs@planet.nl>
> To: <personal_submersibles@psubs.org>
> Sent: Monday, March 01, 2004 4:15 PM
> Subject: Re: [PSUBS-MAILIST] thru hull fittings
>
>
> > Brian, Alec,John,
> >
> > I made the drawing. Machining an o-ring grove in the fitting seems
rather
> > difficult to me so i thought instead of making a grove in the shaft why
> not
> > do it this way. It's not according the books, but i can not imagine why
it
> > shouldn't work.
> >
> > John, i am also interrested in your ideas on machining internal groves.
> >
> > Greatings,
> >
> > Thijs Struijs
> >
> > ----- Original Message -----
> > From: "Alec Smyth" <Asmyth@changepoint.com>
> > To: <personal_submersibles@psubs.org>
> > Sent: Monday, March 01, 2004 3:53 PM
> > Subject: RE: [PSUBS-MAILIST] thru hull fittings
> >
> >
> > > Yes, this is for the drop weight, but no, I didn't do what Thijs just
> > > proposed. I'm afraid to say I just went with plain old grooves on the
> > > shaft. The grooves will weaken it a bit, its true, but on the other
hand
> > > the shaft is pretty massive and is supported where the grooves are.
> > >
> > > Alec
> > >
> > > -----Original Message-----
> > > From: Brian Cox [mailto:ojaibees@ojai.net]
> > > Sent: Sunday, February 29, 2004 11:28 PM
> > > To: personal_submersibles@psubs.org
> > > Subject: Re: [PSUBS-MAILIST] thru hull fittings
> > >
> > > 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
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > > ================================================================
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References:
- RE: [PSUBS-MAILIST] thru hull fittings
  - From: "Alec Smyth" <Asmyth@changepoint.com>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: Thijs Struijs <thijs-struijs@planet.nl>
- Re: [PSUBS-MAILIST] thru hull fittings
  - From: "Dan H." <jmachine@adelphia.net>
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