RE: [PSUBS-MAILIST] Viewport Question.

["Jon Wallace" <jon@psubs.org>]

Hi James,

Do you have the Handbook of Acrylics by Stachiw?  Chapter 7.5.5 discusses
this issue.  He says 1.5mm for axially compressed gaskets or wedged in
o-rings as the primary seal.  Greater than 1.5mm may lower the critical
pressure of the window.  If you use a window with a radially installed
o-ring, he says the diameter of the fitting should provide a "snug" fit.

Jon


-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of James
Frankland
Sent: Tuesday, December 11, 2007 6:02 AM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Viewport Question.


Hello All.

Quick question regarding viewports tolerance.

Ive started machining and have done 2 at the moment.  Ive machined the depth
of the bore to be exactly 1.25 inches as per the plans, and the inside
diameter i have machined to 8 inches plus a clearance of 0.5 mm to allow the
lense to drop in.  (sorry, the plans are imperial but we're metric here, so
its a bit of both).

Im not making the acrylic lenses myself, i will buy them (probably from
psubs store).  Assuming they come in exactly at 8 inches OD, as things are
they should slot in nice and tight.

But Dan H mentioned to me that he got some slight distortion on the ports
after welding.

So the question is, do you think 0.5 mm clearance is enough?  Obviously i
cannot alter the ports once they are welded in, and don't want to have to
start machining the lenses, they must fit.

You can have a look here as usual.  Some of the text titles are wrong.  I'll
change them later.

http://www.guernseysubmarine.com/index_files/Page7497.htm

Any thoughts?

Thanks
James




----- Original Message -----
From: Jay K. Jeffries [mailto:bottomgun@mindspring.com]
To: personal_submersibles@psubs.org
Sent: Mon, 10 Dec 2007 20:16:42 -0500
Subject: [PSUBS-MAILIST] Digital Multi-Frequency Scanning Sonar

Here is what looks like a great scanning sonar for a PSUB.  If it is priced
like some of their other products, it should be a great deal.



http://www.imagenex.com/html/881l_imaging.html



R/Jay





Respectfully,

Jay K. Jeffries

Andros Is., Bahamas



A skimmer afloat is but a submarine, so poorly built it will not plunge.







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