[PSUBS-MAILIST] annealing windows

[Sean T. Stevenson via Personal_Submersibles]

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 stress 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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