RE: [PSUBS-MAILIST] Aqua Jet Cutting Acrylic

[Brent Hartwig <brenthartwig@hotmail.com>]

Mark,
 
When I grow up, I don't want to be a crackpot scientist.     Perhaps it's already to late for me. ; )'
 
You might of noticed by now that I posted to Daves post, that I realized that water would be so much better.  Lou had recently told me of a test he did of one of his stainless steel tanks to 1200 psi that was filled with hydraulic fluid, and so I had that stuck in my head. 
 
The test I was talking about would not be of a scaled down view port, just a small pressure tank consisting of two heads with thick welding on and boltable flanges with a gasket between them, so I can unbolt the heads and remove the full sized viewport from inside. I can design the viewport seating area to be able to have interchangeable machined viewport flanges, so I can test more then one type, size, and thickness of viewport if I wish to. I can test both conical and regular edged viewports in the same pressure tank if I felt the unyielding urge. I'll work up a CAD assembly model to better show what I'm thinking.
 
You make a great point that there is a long list of different types of stresses that come into play on a real world viewport.  After much thought, I realized I just want/need to break some thing, and get it on video. : )'      Seriously I think that doing a number of cycle test on different types of viewports and building the pressure tank, would all be good practice towards my sub building skills, with much to be learned in the doing, even if the data would be mostly useless to publish. No worries, I plan to go my PVHO specs for my sub, I just want to do some hands on testing of my own to feel for confident in my contraption for my own peace of mind. 
 
I have three very old and crazed viewports on this K-250, I'm not going to use, that I would be interested in testing to destruction mostly for the kick of it, and get it on video for those interested. I can aqua jet cut the larger diameter 2 inch thick viewport into a number of smaller ones and test them in the small viewport destroyer tank. I can also practice annealing acrylic and doing shrink cycles on these old viewports.
 
I plan to do a unmanned test on my first sub, much like Dan H. did with Persistence, to test allot of things including the viewports.  
 
 
Regards,

Brent Hartwig

---

From: Mark@Harbortronics.com
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Aqua Jet Cutting Acrylic
Date: Thu, 23 Aug 2007 01:21:57 -0700

Make sure you use water as the pressure fluid... don't presume that a scale model is going to react the same... extruded vs continuous cast vs cell cast, age, previous chemical exposure, etc... soooo many variables!  Be berry careful about your assumptions... often it's what you don't know or don't test that bites you in the end.  What's the saying... a little bit of knowledge is a dangerous thing. Tis so true.... there are so many crackpot 'scientists' that are convinced of faulty conclusions based on small bits of test data.  Don't be deluded into thinking that just because one quickly build scaled window design didn't break at some short pressure test doesn't mean that it's going to be 'safe' for use.

 

Testing is essential, but make sure the design of your tests covers all the bases.

 

I'm feeling old and conservative tonite... :)

 

Mark

 

----- Original Message -----

From: Brent Hartwig

To: personal_submersibles@psubs.org

Sent: Wednesday, August 22, 2007 10:52 PM

Subject: RE: [PSUBS-MAILIST] Aqua Jet Cutting Acrylic

Wil,
 
Interesting Idea you have.  My friend Lou, that manufactures stainless steel tanks, has a hydraulic pump that can go up to 1200 psi, which would be like 2694 fsw. We could build a special but small stainless steel tank with a viewport in it and then fill it with hydraulic fluid and test it to destruction, unless the viewport tested can with stand more then 1200 psi. Of course we will need to take into account fatigue cycles as well as different temperatures, as well as a few other things. This type of set up can test different types of polycarbonate viewports as well. I can take digital videos of each test and share them with the group.

 

Regards,
Brent Hartwig

> Date: Wed, 22 Aug 2007 14:08:15 -0700
> From: clientes@tolimared.com
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Aqua Jet Cutting Acrylic
>
> May i suggest a practical approach on this...
>
> The core of the problems seems to be that many of us just want to use
> a simple acrylic disc piece that you can get in a normal acrylic store
> - where they do decorative items more than submarines - and use it as
> a viewport. The truth is when you get your arcylic disk you do not
> know exactly what process it is trough or not - it looks good - and
> you do not want to build a computerized heating facility just to be in
> peace with the Professor or ABS you also do not want to convert in
> acrylic scientific you just want to know what is safe.
>
> The question that arises is : IF they did NOT anything right in the
> factory - (which is a remote or not so remote posibility) what is the
> depth i can do with this - and still be on safe side. Is it fine to do
> half of stachiew and ABS and forget about all those complicated
> proeedings? - or should it be 1/3 ?
>
> So i would suggest somebody who has a water yet and a hydraulic pump
> available cuts out a model series 1:2 from sheet material and tests it
> to destruction in a simple mounting inside a hydraulics cylinder -
> with and without annealing...shrinking...
>
> And hopefully publishes this - of course no guarantee - on this forum.
>
> What is of interest for us all is what is the DIFFERENCE - and a
> educated guess on that.
>
>
> Cheers Wil
> (concretesubmarine.com)
>
>
>
>
>
> Quoting irox <irox@ix.netcom.com>:
>
> >
> > [I have to admit I'm a little shy about posting to this thread given
> > some of the things people have said recently, but, here goes anyway...]
> >
> > Other than Dr. Stachiw stating in his book that all Acrylic viewports
> > require annealing, there are some other things I would consider when
> > thinking about this question.
> >
> > Cast Acrylic viewports require annealing. I expect cast Acrylic to be
> > closer to 'prefect' than any form of cut Acrylic, but it still requires
> > annealing.
> >
> > Other than annealing, you are also required (by ABS[1]) to preform
> > a shrink cycle. The equipment and effort required for the shrink
> > cycle is pretty close to what you need for annealing, so skipping
> > the annealing process wouldn't save much anyway.
> >
> > Ian.
> >
> > [1] - Yes, yes, I know, psub builders are not required to conform to
> > any ABS standards...
> >
> > -----Original Message-----
> >> From: Brent Hartwig <brenthartwig@hotmail.com>
> >> Sent: Aug 22, 2007 10:49 AM
> >> To: personal_submersibles@psubs.org
> >> Subject: [PSUBS-MAILIST] Aqua Jet Cutting Acrylic
> >>
> >>
> >>
> >> Hello Joe,
> >>
> >> I agree with your approach. I was pursuing information to prove it
> >> or not, if the information was to be had from the groups knowledge
> >> base. I plan to anneal my aqua jet cut view ports, unless I get
> >> good solid data otherwise. I was just interested in finding out if
> >> I had found a way to cut out one step out of the process.Brent
> >>
> >> P.S. It looks like Frappr.com is down for a bit.
> >>
> >>> From: joeperkel@hotmail.com> To: personal_submersibles@psubs.org>
> >>> Subject: RE: [PSUBS-MAILIST] Open Discussion's Allowed in PSUB's
> >>> Mailing List> Date: Wed, 22 Aug 2007 10:57:43 +0000> > Brent,> >
> >>> Something like the acrylics issue, my approach is to consider all
> >>> ideas > "suspect" until proven otherwise.> > If there is no
> >>> reference to the "non-annealing" of water jet cut acrylics in > a
> >>> highly specialized and expert Stachiw type reference, then it is
> >>> best to > "assume" it to be a required process based upon the
> >>> previously existing > processes.> > Joe>
> >
> >
> >
> >
> > ************************************************************************
> > ************************************************************************
> > ************************************************************************
> > The personal submersibles mailing list complies with the US Federal
> > CAN-SPAM Act of 2003. Your email address appears in our database
> > because either you, or someone you know, requested you receive messages
> > from our organization.
> >
> > If you want to be removed from this mailing list simply click on the
> > link below or send a blank email message to:
> > removeme-personal_submersibles@psubs.org
> >
> > Removal of your email address from this mailing list occurs by an
> > automated process and should be complete within five minutes of
> > our server receiving your request.
> >
> > PSUBS.ORG
> > PO Box 53
> > Weare, NH 03281
> > 603-529-1100
> > ************************************************************************
> > ************************************************************************
> > ************************************************************************
> >
> >
>
>
>
>
>
>
>
> ************************************************************************
> ************************************************************************
> ************************************************************************
> The personal submersibles mailing list complies with the US Federal
> CAN-SPAM Act of 2003. Your email address appears in our database
> because either you, or someone you know, requested you receive messages
> from our organization.
>
> If you want to be removed from this mailing list simply click on the
> link below or send a blank email message to:
> removeme-personal_submersibles@psubs.org
>
> Removal of your email address from this mailing list occurs by an
> automated process and should be complete within five minutes of
> our server receiving your request.
>
> PSUBS.ORG
> PO Box 53
> Weare, NH 03281
> 603-529-1100
> ************************************************************************
> ************************************************************************
> ************************************************************************
>