[PSUBS-MAILIST] PVHO rules

Sun Apr 21 20:57:15 EDT 2019

Hank,
not quite following you on that. Modern temperature controllers have PID control.
They predict when to turn on or off rather than react to the sensor hitting a 
certain temperature. 
Lots of cheap ones out there. Not saying this is ideal but just an example...
https://www.ebay.com/itm/Dual-Digital-F-C-PID-Temperature-Controller-Furnace-Kiln-Oven-Thermocouple/230780863978?hash=item35bb9c85ea:g:8AAAAOSwPcVVk5Iq
When I was annealing my acrylic I had to drop the temperature by a degree every
hour & was monitoring it through the night. Much better to be able to program
the ramping of the temperature.
Alan

> On 22/04/2019, at 12:09 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan,
> I talked  with Brian Cox because he annealed his own ports.  He is Brilliant in the way he controls the heat.  He uses a variable voltage supply instead of turning the heating elements on and off with a sensor and relay.  He just pre determines the temperature at given voltages and then controls the voltage for constant temperature control.  Just brilliant!
> Hank
> 
> On Sunday, April 21, 2019, 5:23:33 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hank,
> that was great of River to help out!
> If it were me I would definitely machine it seeing you have to machine
> the clamping area off on a pressed dome anyway. Way less work in
> every way. 
> BTW glass artists can ramp the temperature of their kiln down over
> 2 weeks with thick art work. May be ideal to find a local one.
> I am full of suggestions lol.
> Alan
> 
>> On 22/04/2019, at 10:49 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Alan, here is the drawing of the window, big thanks to River for helping with that.  I think it may be easier to just machine it also .  I have sourced the acrylic at 8 inches think already.  I am just waiting to finalize the frame seat design before I pull the trigger.
>> Hank
>> On Sunday, April 21, 2019, 4:33:47 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> 
>> Hank,
>> If it is just 3" deflection then you would need to go to a 8" thick acrylic if
>> you machined.
>> Just thinking there would be less waste around the perimeter on a machined
>> dome as apposed to a pressed dome & you would need to do some machining
>> & polishing on a pressed dome anyway.
>> Might be a lot easier to machine it & build a small oven, or if you know a potter
>> or glass blower with a suitable kiln, get them to anneal it.
>> Alan
>> 
>>> On 22/04/2019, at 9:40 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> Alan,
>>> The lucky thing is it only has approximately 3 inch deflection and I will use hydraulic pressure.
>>> Hank
>>> 
>>> On Sunday, April 21, 2019, 2:31:25 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Hank,
>>> Spelling mistake. Pressure is going to be HUGE.
>>> Alan
>>> 
>>>> On 22/04/2019, at 8:28 AM, Alan <alanlindsayjames at yahoo.com> wrote:
>>>> 
>>> 
>>> Hank,
>>> I had a go at forming an acrylic ring out of a straight piece of 1" thick
>>> cast acrylic, using a modified kitchen oven.
>>> At forming temperature the acrylic was like the hardness of eraser rubber.
>>> Maybe there is technical literature on what shore hardness it actually is at
>>> forming temperature. Anyway if you are forming a 5" block the pressure
>>> Required is going to be used.
>>> When I had a 1" thick dome blown for me they had to stop & get thicker
>>> Clamping rings made.
>>> Emile or Greg may like to comment on this as they have had a lot more experience.
>>> You will need a temperature controller for a kiln, & program it for your requirements.
>>> It will be a few days in the oven I would imagine.
>>> If you machine it, can you get away with not heat treating it afterward?
>>> I would imagine the stress would only be superficial.
>>> Alan
>>> 
>>> 
>>>> On 22/04/2019, at 2:11 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>> 
>>>> Hi All,
>>>> I am looking for the actual PVHO rules for Acrylic forming.  I can find all the references to the rules but not the rules.  I am planning to make a 5 inch thick 60 degree Hemispherical segment either from forming  or from machining out of a thick slab.  I prefer to form it because I will need an oven to heat treat it after anyways, but I don't want to form it without the rules.
>>>> Hank
>>>> _______________________________________________
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>>> 
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