[PSUBS-MAILIST] question

[Cliff Redus via Personal_Submersibles]

 Alan Rick's situation is a bit different from mine.  In my case I have a rectangular slab of cast acrylic that is 3 inches thick.  I need major machining to bring the slab into a rough-cut shape, not just small surface machining.  My reading of Stachiw is that if this casting has never been annealed, then I can expect significant dimensional changes in diameter (shrinking) and thickness (thickening).  His book says that after this initial annealing which he call normalization, no further dimensional changes are expected.  So to me, it makes sense to rough cut the disk from this slab to say 2-3% larger diameter than what my final dimension is, normalize the casting, then do the final machining, and then anneal again using either the PVHO or the Handbook of Acrylic schedule which are different and hope my dimensions don't change.
This is all new to me so, I don't want to screw up this acrylic.
     On Friday, February 7, 2025 at 02:43:09 PM CST, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 I thought that in a previous email Greg was quoted as saying that the machined surface could craze if not annealed & the machining  wouldn't effect the strength of the view port. I had summised from that that If Rick machined the edge any crazing wouldn't show & annealing wouldn't be necessary. Or will the crazing effect any sealing?

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  On Sat, 8 Feb 2025 at 9:03 am, hank pronk via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   _______________________________________________
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