[PSUBS-MAILIST] annealing acrylic

Tue Apr 1 21:03:02 EDT 2014

Hi Brian,
don't know about that idea, sounds like a lot of work.
I managed to form some 1&1/2" thick acrylic in a kitchen oven by
cutting a hole between the upper oven & lower oven & heating the
upper oven with the lower (warmer draw) element. I can't remember
whether I had the fan on or not, but I could manually raise the temperature
by 1degree Celcius every 10 minutes & drop it by 1 degree every 15 minutes.
The oven thermostats are useless & the actual temperature fluctuates wildly from what 
you set it at on the dial. The lower element was so slow at heating the upper oven through the
small hole, that it made it easy to control. I had a probe type thermometer like you had.
If you had a low powered element in a big oven with a fan circulating the air, you should get
there, as long as the element was powerful enough to get you up to your top temperature.
As mentioned before the kiln controller is designed for exactly what you are doing & it has 
a fine adjustment range.
On the safe side, if you aren't confident about the process I'd follow what others had suggested 
& get them done professionally. 
I remember someone saying that Captain Kitrege tested 2 identical domes, one annealed &
the other not. The annealed dome went to 800 ft & the other broke at 50 ft. ( I think that's right)
Alan

________________________________
 From: Brian Cox <brian at ojaivalleybeefarm.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Wednesday, April 2, 2014 12:50 PM
Subject: Re: [PSUBS-MAILIST] annealing acrylic

Alan,
           I was thinking get a small electric water heater ( 5 gal) fill it with glycol and circulate it though a large open reservoir that has an opening at the top.  Make a special sealed container that the viewport could be housed in and dump it into the pot.  Then regulate the temperature of the water/glycol fluid using a cooling radiator and flow valves to channel more or less water through the cooling fan.  Have everything on variable solenoid valves.  Hook it up to your computer and control everything from there.

Brian   

--- alanlindsayjames at yahoo.com wrote:

From: Alan <alanlindsayjames at yahoo.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] annealing acrylic
Date: Wed, 2 Apr 2014 07:02:51 +1300

Brian,
I was going to suggest earlier that you build a larger oven next to your small
oven & use the small oven to heat it. That way the temperature fluctuations
would be less dramatic.  Possibly make it out of insulation batts & aluminium foil.
you could still use the control unit I suggested. 
Alan

Sent from my iPad

On 2/04/2014, at 3:49 am, "Brian Cox" <brian at ojaivalleybeefarm.com> wrote:

Epic Fail !    my attempt to anneal a viewport did not go well.   The temps swings were so great that it was impossible to regulate.  The mass in the oven that I had hoped would moderate the swings made it so the lag time between the heating cycle and when the thermometer sensor saw the temperature change uncontrollable.   And the heat was not even though out the oven as well.
> 
>Brian
>
>--- hanker_20032000 at yahoo.ca wrote:
>
>From: hank pronk <hanker_20032000 at yahoo.ca>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>Subject: Re: [PSUBS-MAILIST] annealing acrylic
>Date: Tue, 25 Mar 2014 05:35:51 -0700 (PDT)
>
>
>Brian,
>I say when in doubt, test.  If your not building a test chamber , you can make your sample window to fit my chamber and I will test it for you.
>Hank
>
>
>
>On Monday, March 24, 2014 7:23:18 PM, Brian Cox <brian at ojaivalleybeefarm.com> wrote:
> 
>Hank,
>          I have the book, that's where the annealing schedules are, they vary quite a bit, there is an absolute minimum time and then there is the original recommended time. The recommended time comes out to be around 51 hours where as the shortened time is maybe half that.  I'm just doing one test piece to start off with.  I was also using the same oven ( a toaster oven I got from Sears for $75 bucks) to heat the welding rod to 250 degrees F before we used the rod ( it had been sitting out for a few days).  I was able to keep the temperature fairly even for the welding rod at 250.  
> 
>Brian  
>
>--- hanker_20032000 at yahoo.ca wrote:
>
>From: hank pronk <hanker_20032000 at yahoo.ca>
>To: Personal Submersibles General Discussion
 <personal_submersibles at psubs.org>
>Subject: Re: [PSUBS-MAILIST] annealing acrylic
>Date: Mon, 24 Mar 2014 17:39:27 -0700 (PDT)
>
>
>Brian,
>Do you have the Stachiw book of Acrylics, I can send you mine if you don't have a copy.  There is some pretty important stuff in there.
>Hank
>
>
>
>On , hank pronk <hanker_20032000 at yahoo.ca> wrote:
> 
>Brian,
>How thick is your acrylic?  should take more than a night?
>Hank
>
>
>
>On Monday, March 24, 2014 6:33:09 PM, Brian Cox <brian at ojaivalleybeefarm.com> wrote:
> 
>Yes, I have the annealing schedules.  I have an electric oven and two digital thermometers, one I'm going to put in a piece of acrylic and the other one I'm going to use to monitor the oven temperature itself .  I'm worried that the thermometer in the acrylic won't register until it gets heated throughout, and so then the oven temp might go higher than it should.  So between the two readouts I can heat it gradually up.  It'll be a long night.
> 
>Brian
>
>--- hanker_20032000 at yahoo.ca wrote:
>
>From: hank pronk <hanker_20032000 at yahoo.ca>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>Subject: Re: [PSUBS-MAILIST] annealing acrylic
>Date: Mon, 24 Mar 2014 17:22:32 -0700 (PDT)
>
>
>Brian,
>Are you going to anneal your windows yourself?  
>Hank 
>
>
>
>On Monday, March 24, 2014 6:03:10 PM, Brian Cox <brian at ojaivalleybeefarm.com> wrote:
> 
>Used my polarized lenses on the newly cut piece and it appears clouded throughout the whole piece.  Where as another piece I have, you can clearly see a stress area around where it has been drilled. 
> 
>Brian
> 
>
>--- emile at airesearch.nl wrote:
>
>From: "Emile van Essen" <emile at airesearch.nl>
>To: "'Personal Submersibles General Discussion'" <personal_submersibles at psubs.org>
>Subject: Re: [PSUBS-MAILIST] annealing acrylic
>Date: Mon, 24 Mar 2014 22:40:46 +0100
>
>
>As far as I know it is
only cast.
> 
>Regards, Emile 
>  
>Van:Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] Namens Brian Cox
>Verzonden: maandag 24 maart 2014
20:37
>Aan: PSubs 
>Onderwerp: [PSUBS-MAILIST]
annealing acrylic
>  
>I'm planning on annealing my viewports,  does anyone
know if the acrylic from the factory is pre-shrunk ? 
>  
>Brian _______________________________________________
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