Re: Visibility / Safety or Safety / Visibility ?

[shawl@torchlake.com (Jonathan Shawl)]

As far as the heat treating cycles, that is up to the owner/builder. If they get
either one of the reports mentioned, they will learn what is required. I was only
offering to turn a piece of plastic to your specs up to 10" dia. I have a vacuum
face plate needed to hold the lens wile turning the edge. The holding force on a
8" lens, at 1 atm. of pressure is about 735 lbs.
It holds very well! When roughing out my first one I wanted to see how well it
would hold. I took a heavy cut until I stalled the 1/2 hp motor and the lens
didn't slide or move. Depending on the size and design, I think I could cut up
the sheet and turn it round for about $50 to $90 each lens. I don't remember what
the name of the Co. I got the plastic from but a 24"X24"X1.25" sheet cost me
about $75 mail order back about 15 years ago. From this I made 9 lenses, 7.75" od
by 5 " across the inside. A friend of mine got some odd size small pieces at a
discount, so ask if they have any thing like that to get a better deal. Even if
you have some waste, you can come out ahead.   I then turned aluminum rings and
using silicone to set them into the ring. Then I bolted this assembly to the
steel ring that was welded into the hull.
WARNING, This design won't pass all the codes in the ASME report because I don't
have a retainer ring on the outside. I'm not saying you don't need the ring, I
just didn't do it. The danger is that if you ever encountered a positive pressure
event the lens could blow out. My hatch leaks first.
Jon Shawl

protek@shreve.net wrote:

> This thing on windows;  You need to cut a piece of acrylic larger than what
> you need by maybe 15% in diameter.  Then shrink cycle it first before you
> machine it.  Then machine it and then anneal it.  Two heat treating cycles
> are required. "Acrylic Plastic Viewports" J. Stachiw...
>
> GB
>
> At 08:33 PM 2/23/99 -0500, you wrote:
> >> I'd like hear about where viewports can be purchased for a 200-foot
> >> depth.
> >>
> >> Michael B. Holt
> >> Oregon Hill, Richmond, Virginia, U.S.A.
> >>
> >
> >  Hi Mike
> >As far as buying view ports I don't know where you can get them. I sent for
> >the report PVHO from ASME to learn how to properly make the lenses. Then I
> >made my own from 1.25 in thick cast acrylic sheet and cut it up on a saw
> >into octagon shapes. Then I turned them down round on my lathe. I have the
> >tapered seat design. I could make some more ASME approved design lenses, but
> >because I am not a ASME certified builder , the lenses would not be
> >technically ASME approved. Do you see what I'm saying?
> >
> >If some one used this report, did there own design work, and sent me the
> >material and a drawing, I could do the machining.
> >That way you are responsible for whatever happens not me, you would also
> >have to make a test rig and test your own lenses before installing them.
> >That way I am just cutting a piece of plastic for you and I would not be the
> >one saying it would be ok to use them as view ports. The maximum Dia. that I
> >can turn in my lathe is about 10".
> >
> >
> >Let me know, Jon Shawl
> >Have you seen my sub? http://www.nwcis.com/submarine/
> >
> >
> >
> >