Re: [PSUBS-MAILIST] Rudders

[Jon Wallace <jonw@psubs.org>]

Annealing is interesting stuff.  Stachiw shows a hold time of 14 hours 
at 170F and cautions on page 838 that spherical and cylindrical shapes 
which are thermoformed (as opposed to machined to the desired shape) can 
lose their shape somewhat if annealed at temps above 180F.  I was 
wondering the other day if annealing via water immersion would be a 
reasonable alternative to air convention, for the home owner.  Annealing 
ovens tend to be expensive and home ovens just won't work.  It seems 
like good temperature control could be achieved with water immersion and 
such a unit shouldn't be very difficult or expensive to build using 
propane as a heat source.

Jon



Greg Cottrell wrote:
Make sure that the fabricator is going to anneal the dome- this is where 
the strength comes from. Ask them to give you the annealing schedule. 
For a 1" thick dome it should be 179 F held for 24 hours in a convection 
oven, Then cool at no more than 10 F per hour for 6 hours, fan off. If 
you're not convinced that they know how to do this then give me a call 
and I'll do it here.



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