Re: [PSUBS-MAILIST] thru hull fittings

["Brian Cox" <ojaibees@ojai.net>]

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
> > > >
> > > >
> > >
> > >
> > >
> > >
> >
> >
> 
> 
>