[PSUBS-MAILIST] Gamma bow dome

Fri Feb 27 19:47:08 EST 2015

Pete,
I have not finalized that part yet. 
Hank--------------------------------------------
On Fri, 2/27/15, Pete Niedermayr via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Gamma bow dome
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Friday, February 27, 2015, 6:39 PM

 Hank, What are you going to do for a
 front ballast tank?

 Pete
 --------------------------------------------
 On Fri, 2/27/15, Alan James via Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:

  Subject: Re: [PSUBS-MAILIST] Gamma bow dome
  To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
  Date: Friday, February 27, 2015, 2:20 PM

  James,in your
  retaining ring photo, what are the four protrusions
  with holes in,
  on the inside of the ring for?Alan

   From: James Frankland
  via Personal_Submersibles
  <personal_submersibles at psubs.org>

  To: Personal
  Submersibles General Discussion
  <personal_submersibles at psubs.org>

  Sent:
  Saturday, February 28, 2015 4:49 AM

  Subject: Re:
  [PSUBS-MAILIST] Gamma bow dome

  It took me
  about 5 mins to do the drawing on MS paint! I think
  you mean something like Stachiw's book, page 524 fig
  11.76.  Bottom drawing.  Probably will work just as
  well.  No machining required!

  On 27
  February 2015 at 15:35, Alec Smyth via
 Personal_Submersibles
  <personal_submersibles at psubs.org>
  wrote:
  Thanks,
  you went to some trouble making that drawing, but it
  certainly added clarity. In my case the outside wall of
 the
  acrylic is completely square and there's virtually no
  gap at all between seat and window, its literally a few
  thousandths. I could machine the seat to take an O-ring
  groove, as you did with the retaining ring. However, PVHO
  2-2.11.1 says "As primary seals for standard window
  geometries shown in Figs. 2-2.1 through 2-2.4, a soft
  elastomer compressed between the high pressure face of the
  window and retainer ring will be acceptable. The soft
  elastomeric seal may take the form of a flat gasket, or a
  seal ring with O, U, or X cross section." 
  Given its
  so easy to cut out a circular flat gasket, I think I'll
  try that first and see how it goes. If there are nuisance
  leaks, I could upgrade to an O ring by machining the
  appropriate groove, but I'll try the lazy approach
  first. These bolt-on window seats are nice in that they
  allow for later modification. 

  Best,
  Alec

  On Fri,
  Feb 27, 2015 at 9:56 AM, James Frankland via
  Personal_Submersibles <personal_submersibles at psubs.org>
  wrote:
  Hi
  Alec, The
  epdm gasket was really just to relieve stress on the seat
 of
  the dome.  This was with advice from the guy who built
 the
  Canary island subs who came to visit me.  Although of
  course it should provide sealing at higher pressure. 
   Emile made the dome and mounting
  ring and suggested I would need another seal for low
  pressure.  So, I made the low pressure seal an O ring
  sitting in a machined groove in the retaining ring.  
   See hastily drawn picture. 
   The gap where the O ring sits is
  nowhere near as severe as it looks in the picture, which
 is
  of course not to scale or anything.   I would love to
 say
  it was carefully engineered, but im afraid I just winged
 it
  a bit.  To start with the O ring groove was just a
  chamfer.  This didn't work as I couldn't get the O
  ring to stay in.  Then I machined it for a very small O
  ring.  Couldn't get it in.  Eventually, I got a groove
  and O ring combination that seemed to work.  There is
 lots
  of silicone grease on all surfaces as well.  It doesn't
  leak.  RegardsJames 

  On 27
  February 2015 at 14:05, Alec Smyth via
 Personal_Submersibles
  <personal_submersibles at psubs.org>
  wrote:
  Hi
  James,
  That's some good
  looking hardware! Just a question if I may. Do you have
 just
  the gasket for making a seal, or is there an O-ring as
  well? 
  My project
  sub has a bow dome seated in an aluminum ring. Currently
 the
  window is just sitting on a gasket with no O-ring, but
  I'm wondering whether to switch to an O ring. The window
  seat is 90 degrees square, so one possibility would be to
  chamfer the edge of the acrylic and put an O ring in the
  angle. That is what I did on Snoopy's hatch dome, it
  worked well and is a solution that doesn't require any
  changes to the seat. The other option is to put an O ring
 at
  the top of the acrylic and squeeze it with the retaining
  ring, but that would mean machining a chamfer into the
 seat,
  and would require machinery larger than what I have here.
 Or
  of course I could do nothing and see if it seals well with
  just an EPDM gasket.

  Thanks,
  Alec
  On Fri,
  Feb 27, 2015 at 8:40 AM, James Frankland via
  Personal_Submersibles <personal_submersibles at psubs.org>
  wrote:
  Hi
  Hank.   Yes, agreed, my dome does
  sit on a gasket.  The actual edge of the acrylic itself
  sits on a 1mm epdm gasket that sits onto the aluminium
  ring.  That ring bolts to the main reinforcing ring and
 has
  an o ring like you say.  Maybe this does give it a little
  bit of leeway. My dome is off at the
  moment, so I will have a look at the weekend and see if I
  can see any distortion on the reinforcing ring.  Im
 pretty
  sure there is none, or none that is detectable by the
 naked
  eye\straight ruler.  The alu ring seems to fis to it
  perfectly.   I suppose the best
  option is like you say, get it machined after welding. 
 You
  wont have to worry at all then. 

  On 27 February 2015 at
  13:23, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
  wrote:

  James,

  I am just assuming it needs to be perfect ? and I can not
  imagine that it will not warp at least a small amount.  I
  am not experienced with how such heavy material will
 react.
  Your dome sits on a gasket witch may give you some
  forgiveness. Maybe Emile can comment having done this
  also.

  Hank--------------------------------------------

  On Fri, 2/27/15, James Frankland via
  Personal_Submersibles <personal_submersibles at psubs.org>
  wrote:

   Subject: Re: [PSUBS-MAILIST] Gamma bow dome

   To: "Personal Submersibles General Discussion"
  <personal_submersibles at psubs.org>

   Received: Friday, February 27, 2015, 7:28 AM

   Do

   you need to go to all that trouble?  When I did mine,
  the

   reinforcing ring was milled flat on the seating surface
  and

   I just pre-heated it and welded it in.  It was so big
  I

   don't think there was any distortion and it
  doesn't

   leak. Just thinking of saving you

   what sounds like an expensive job.

   On 27 February 2015 at

   11:45, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>

   wrote:

   James,

   I am amazed at the equipment some of the big shops have.
  A

   vertical mill is probably the way to go.  I am checking
  out

   another option also.  There are machines made to
  machine

   pipe flanges that clamp on and are portable.  There is
  a

   company in Calgary that specializes in this. I am just
  not

   sure yet what the accuracy is yet.  It is nice that I
  live

   only 3 hr from a big oil town that caters to the oil

   industry.  You can tell that oil is low, and the shops
  are

   slower.  I ordered the ring on a Friday and it was
  ready

   Monday.

   Hank    --------------------------------------------

   On Fri, 2/27/15, James Frankland via
  Personal_Submersibles

   <personal_submersibles at psubs.org>

   wrote:

    Subject: Re: [PSUBS-MAILIST] Gamma bow dome

    To: "Personal Submersibles General
  Discussion"

   <personal_submersibles at psubs.org>

    Received: Friday, February 27, 2015, 4:08 AM

    Hi hank,Sounds like

    it will be a good

   modification.  How are they going to

    machine the ring?  Some sort of vertical

    mill?RegardsJames

    On Friday, 27 February 2015, hank pronk via

    Personal_Submersibles <personal_submersibles at psubs.org>

    wrote:

    Today I

    officially took the plunge and removed the forward

   ballast

    tank to install my new bow dome.  After much agony I

    decided to make the change.  I am not enjoying the
  sub

    because the forward window arrangement is not ideal
  for

    lakes with marginal visibility.  I went to the big

   city

    yesterday and picked up the reinforcing ring and
  should

   have

    it fitted in a couple of days.  I am bringing in a

   pressure

    welder to weld the ring and then the sub is off to
  the

   big

    city to machine the ring.

    Hank

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