From what I rememer reading about polycarbonate is it's generally much more scratch resistant then acrylic and you don't need to anneal it after cutting it. I don't know if you would need to anneal it after therma forming it or not, or even if it can be therma vacume formed? The Hyzod polycarbonate I've seen used in are hyperbaric chamber project had good optical properties from what I rememeber.
If I water jet cut and then lathe turn a bevel into a thick piece of acrylic, do I need to anneal it? The water jet cutter does not heat up the material it cuts, and can cut over 7 inch thick material. When cutting really thick materials it will cut more material as it goes deeper on either side of the cut making a little bit of a bevel. That bevel can be calculated and if need be a larger radius cut then needed can be cut and then the view port can be lathe turned to clean it up. The water jet cut does leave a very clean cut, so for people that are not needing a bevel in there view port, you are done and ready for install. I plan to have allot of my metal plate parts cut with the water jet cutter as well since it's such a clean exact CNC cut, and I can do the 2D CAD drawings needed to run the CNC machine.
Thanks for your help. The Society for the Creation of Unique
Machines (SCUM) thanks you! ;-)
Regards,
Brent
From: "George Slaterpryce" <gslaterp@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Great Update on the old K-250 sub in Sandpoint
Date: Wed, 7 Feb 2007 16:18:38 -0500
>Polycarb generally failed by layered fractures... I.E. dispite the
>ugly visual, it looked like one of those fungus toenails. flake and
>crack and also tended to fail at the edges and work it's way in...
>although I think that was more of a problem of how I mounted the
>lenses. They didn't shatter like glass. Also repeated stress caused
>little fractures and chips on the edge.
>
>Method of testing was by submergence on a test can (a pipe with a
>fitting for the viewport) lowered by measured rope with a 30lb
>weight at the end. which gives my depth reading a margin of error
>because of current, but negligable. I attempted to righ a waterproof
>camera within the can in such a way that when the port failed the
>preasure would snap off a picture of the failure. Unfortunatley it
>was quickly discovered that the depth of failure exceeded that of
>the camera housing and ruined the camera. The next attempt was
>rigging my infamous ping pong ball switch that failed even more
>miserably. Finally I was able to detect failure (breach) of the can
>by purchasing a CCD camera and mounting that in the can with cable
>to the surface behind an acrylic lense... not the best picture in
>the whole world because I over did the inner lense by quite a bit,
>but I was able to tell on the screen when water was getting into the
>unit... and found out that failures weren't "Immediate" and where
>generally preceeded by a couple seconds of seepage on the seal. then
>it would "Pop" more offten than not into the can. However when the
>seal clamp held it would spider, and then quickly fill. General
>depth for a lense that was 3mm thick was about 100ft, which I think
>again had more to do with my clamping method than anything because
>those genreally "popped". Spider failures where much deeper and
>eratic in depth.
>
>
>----- Original Message ----- From: "Ian Roxborough"
><irox@ix.netcom.com>
>To: <personal_submersibles@psubs.org>
>Sent: Wednesday, February 07, 2007 4:25 PM
>Subject: Re: [PSUBS-MAILIST] Great Update on the old K-250 sub in
>Sandpoint
>
>
>>
>>Oh, that was one other thing I meant to mention. If I remember
>>correctly, Acryilic has the better optical properties, although
>>it would be nice if somebody could confirm that for sure (I
>>know Acryilic is way better than glass).
>>
>>Did you take any notes when destructively testing the
>>polycarbonate lens? Any worth sharing? Particularly about
>>how it failed.
>>
>>Ian.
>>
>>On Wed, 7 Feb 2007 13:22:21 -0500
>>"George Slaterpryce" <gslaterp@hotmail.com> wrote:
>>
>>>Poly turns all "Rainbowy" for lack of a better term before
>>>failing. I did
>>>some test with polycarb lenses cut by my friend who owns an
>>>optical shop.
>>>(was trying to fix the warping associated with filming underwater
>>>and was
>>>trying different lense types)... then again these where for camea
>>>ports. not
>>>domes. But I would think the rainbowy effect would still exhibit.
>>>
>>>
>>>----- Original Message ----- From: "Ian Roxborough"
>>><irox@ix.netcom.com>
>>>To: <personal_submersibles@psubs.org>
>>>Sent: Wednesday, February 07, 2007 12:48 PM
>>>Subject: Re: [PSUBS-MAILIST] Great Update on the old K-250 sub in
>>>Sandpoint
>>>
>>>
>>> >
>>> > Using polycarbonate would be either too risky (very little
>>>data)
>>> > or too expensive (cost for the safety research) when compared
>>> > to Acrylic. Much research has been done on Acrylic and it's
>>> > relatively cheap be buy the findings. Even if polycarbonate
>>> > had the same amount of data avaliable, I would still choose
>>> > Acrylic because it will turn milky long before failing, where
>>> > as polycarbonate would fail without warning.
>>> >
>>> > Cheers,
>>> > Ian.
>>> >
>>> > On Wed, 07 Feb 2007 06:30:34 -0800
>>> > "Brent Hartwig" <brenthartwig@hotmail.com> wrote:
>>> >
>>> >> Fantastic, It's nice to know we have good options. Are
>>>these view
>>> >> ports just the glass or the glass and the metal framework? I'm
>>> >> thinking I
>>> >> might like to use polycarbonate for a number of reasons. But I
>>>need to >> do
>>> >> a list of pros and cons compared to acrylic. There is a number
>>>of
>>> >> different brands and types in those brands that most have
>>>different
>>> >> advantages to compare as well. It's like going to school. So
>>>you could
>>> >> say I need to be schooled. : )'
>>> >>
>>> >> Brent
>>> >>
>>> >> ------------------------------------------------
>>> >> From: "Jon Wallace" <jon@psubs.org>
>>> >> Reply-To: personal_submersibles@psubs.org
>>> >> To: <personal_submersibles@psubs.org>
>>> >> Subject: RE: [PSUBS-MAILIST] Great Update on the old K-250 sub
>>>in
>>> >> Sandpoint
>>> >> Date: Wed, 7 Feb 2007 08:00:29 -0500
>>> >>
>>> >> Hi Brent,
>>> >>
>>> >> I'm currently in talks with a manufacturer of certified ASME
>>>PVHO view
>>> >> ports to offer these through PSUBS. I have no idea what they
>>>would >> cost,
>>> >> but it's an option you might consider if you choose to replace
>>>the >> view
>>> >> ports.
>