www.TK560.com

[dbc1218]

Some of you might have seen my former a while back on this site http://www.instructables.com/id/S99X59OF3JEUCR7/
I want to rebuild it to an over/under design so I need to clean the melted plastic off the nichrome wire. Should I just hook it back up and let the plastic melt off or is there a better way?

[TK 109]

hmm...

i say, melt the plastic off the coils, just set it outside on a warm day, and pick off the melted bits off the oven floor. or you could replace the nichrome...
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-Alex

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[cod]

it wouldn't hurt to try and melt it off I say. what kind of plastic are we talking about here ? PETG will produce little or no toxic fumes. not so sure about others.
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<.o'>

[AlterEgos]

I have to agree with TK and Cod. The best way to get the plastic off without damaging the wire is letting it melt. It may take a while or even a few melting sessions to get it all, but I don't think disturbing the wire is a good idea unless you're willing to replace it.

Just be sure to do it outdoors, since styrene and ABS emit some serious fumes as it burns/melts.
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-John

[dbc1218]

I ended up taking the coils off and burning the styrene off with a lighter. It worked pretty well but it needs to be done outside, this makes a lot smoke and soot. I've almost finished the new over/under former and will be posting it on the instructables website.

[TK 109]

that'll do it!

yeah, stuff smells when it's burning...
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-Alex

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[jegner]

I think that everyone who home vacuum forms, will at some point, melt some plastic. Part of the process. I just let my coils burn off the plastic, then scraped with a putty knife the residue from the oven floor. My ceramic posts got the worst of it, and I had to take the oven apart to get them clean. Mostly scraping with the putty knife. The coils were fine, still going strong! I've had a couple of close calls since. but a 1 minute timer really helps me keep an eye on things. I found an old dark room timer, and it works great.

As for the flip flop design. very similar to my mark I version. It did something similar. Problem with that design, the plastic droops right onto the coils. A deeper oven box really helps. You may not need to re build the whole thing. Just ad 6 inches to the top of the oven, and remake the hinge.

Just some thoughts.

Jim

[mnttech]

[TK 109]

hey jim,

i haven't toasted any plastic on my coils yet! i think i'll go out and do that now... (JK)


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-Alex

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[Fredo]

mnttech, Maybe you could lower your oven the same amount you raise the sides of the oven then nothing would change in relationship to the frame and platen.?........................Fredo

[mnttech]

Fredo,
Nice thought, but the oven sits on a metal frame, and I still have not figured out how to weld yet. Thanks for the input.
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Never force anything, always get the bigger hammer.

[jegner]

Take a look at this design. It was found some years ago on the net, but the link no longer works. This was the design I first used for my mark I model.

http://members.aol.com/KMyersEFO/vacuum.htm%20 [link no longer works]

But here is a copy of the image from that site.

Take note of how the oven and the platen are on different levels. Maybe this will fix your problem, and was what I was thinking. A better idea is to lower the oven as oppose to raising the frame.

[AlterEgos]

Like TK 109, I have yet to make styrene flambe' either.

The trick is to watch your plastic like a hawk while it's heating up. My frame doesn't sit exactly flush with the oven top, so I have about a 1/4" gap near the rear that allows me to view the plastic as it sags.

I also have a temperature controller, so when the plastic sags really fast (due to the oven being on for a long period of time) I can lower the heat setting to compensate.
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-John