[PSUBS-MAILIST] annealing windows

[Emile van Essen via Personal_Submersibles]

Te centre of the acrylic will reach the same temp as the air. 

Buto it will take some 2 hours for 40 mm plate!

 

Regards, Emile

 

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Van: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org]
Namens Sean T. Stevenson via Personal_Submersibles
Verzonden: zondag 22 november 2015 17:23
Aan: Personal Submersibles General Discussion
Onderwerp: Re: [PSUBS-MAILIST] annealing windows

 

Brian, just wanted to make sure that the thermocouple in the acrylic sample
is only for monitoring the heat soak, and is not the one you are using to
control the oven temperature? Obviously, the centre of the acrylic is going
to be cooler than the oven air.

What is the arrangement of heating elements? Are there fans to circulate the
air in the oven to homogenize it? If so, you might look at diffusing that
airflow. You only need enough to prevent temperature gradients in the oven.
You might have a hot spot across from a fan?

Sean

 

On November 21, 2015 9:27:47 PM MST, Brian Cox via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:

Alec,   yes, correct, the window with the hole for the probe is just to
monitor the temp.  I wonder if any of those psubers across the pond would
have any experience with something like this.

 

Brian C.

--- personal_submersibles at psubs.org wrote:

From: Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion
<personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] annealing windows
Date: Sat, 21 Nov 2015 23:00:28 -0500

Brian, just to make sure I understand... I presume the window with the hole
was a "placebo" you threw in the oven along with the actual windows, to
monitor temperature rise? Else, if you drilled a partial hole into one of
the actual windows unfortunately my reaction would be a very big UH-OH!!!
That would be a stre! ss concentrator in a spot where you really do not want
one.

 

 

Best,


Alec

 

  

 

On Sat, Nov 21, 2015 at 10:32 PM, Brian Cox via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:

Had a weird observation while annealing my windows,  I have one window that
I drilled a 1/8' deep hole for a temperature probe so I can monitor the rise
of the acrylic.  After the annealing, the one window with the probe, it's
surface was badly melted.   The rest of the windows were perfectly fine.
The only difference was that the! window with the probe has gone through
multiple annealing cycles. It was also sitting on another piece of thick
acrylic, but I don't think that would have anything to do with it's surface
being melted.

 

Brian Cox


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