Know your material!!!

I was trying to make a replacement for the witness window on the manual actuator I'm attaching to a Road Wing for a forum member. I found a piece of pipe the very diameter of the housing, and polished it nice and clean and smooth, thinking what a fine sag mold it would make for polycarbonate. So I got into my cheat sheet and arrived at 385 degrees being my target temp in my calibrated kiln that I heat treat rivets and small parts in.

So I program the oven to ramp up and hold the desired 385 degrees. No problem, Paragon ovens with a Sentry controller are really nice. I let it stabilize at temp for about 1/2 hour, as I have 2 pieces of L angle in there steadying my expertly crafted sag mold. I walk over, flip the door open and place the chicklet of plastic, about the size of a match box, on the mold surface and close the door. I recall that my soak time will likely be less than 5 minutes. So I listen to "Smokin in the Boy's Room" and go open the door, and find this lump of stuff that looks like a plastic pork rind sitting on top of my mold! What could have happened? Mister infrared non-contact thermometer comes out and says 384 is the surface temp of my mold. Did I read it right? Did I mis-program somehow or over shoot the temp? Did not stick around for another try last night, but a guy came to me today looking for some polycarbonate to make a drill template. "It's over there behind the mill, but something is wrong with that Lexan" I said, confident in my methodology. He asked why, and I relayed my experience to him, all the while he was grinning. He then informed me that the plastic pork rind was the result of me using ACRYLIC sheet instead of polycarbonate! Well that explains it, since cell cast sheet Acrylic molds at around 350 degrees max, and boils soon after!
Next round is getting done in the apartment, where I can watch the work sag out through the window with the light on.

I'm not letting you work on my sagging parts.

Not unless you want to run the risk of them looking like pork rinds!

AND, the stuff I have now says LEXAN right on the covering!

I thought the 1st rule of thermo-forming was... you don't talk about thermo-forming

DageonYar wrote:
I thought the 1st rule of thermo-forming was... you don't talk about thermo-forming

It's... you know what?..

Amazing how much better the correct material works at the correct temperature!

They are not perfect (not like I put felt on it or anything) but it's gonna lay right down and look good. 3rd one in the oven now. I'll jack up at least one figuring out how I want to cut and shape it.

DageonYar wrote:
I thought the 1st rule of thermo-forming was... you don't talk about thermo-forming


That's the first thing that came to mind when I saw the title of the thread too

Two chemists walk into a bar, the first one says "I'll have some H2O." to which the other adds "I'll have some H2O, too." The second chemist died.

Ha ha ha. (Love nerd jokes).

I'm not a nerd so I had to look it up But that would do it