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thebluecanary
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Joined: 02 Feb 2006
Posts: 123
Location: St. Louis, MO

PostPosted: Tue Feb 14, 2006 8:35 am    Post subject: Reply with quote

crashmann wrote:
I prefer to run my oven outside so the obnoxious fumes don't build up in my house. But when the temperature drops, or it's very windy, I run the oven just inside the basement door with fans running. The fumes may not be toxic, but some of the folks I've seen at GE Polymershapes are a few beers short of a 6 pack! Good ventilation is very important!

When you flip the switch, you've got to holler out the mandatory "Fire in the hole!"

Charlie
TI-386


How bad are the fumes? I can't run mine outside, I really don't have a backyard, but a large workroom. Other then being toxic, are they flamable? (fumes that is) I dought they are, but I thought I should ask. I have a charcoal filter breathmask. What about running an Air Purifier. At the least it should help keep the smell out of the rest of the house.
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crashmann
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Joined: 27 Sep 2005
Posts: 501

PostPosted: Tue Feb 14, 2006 8:49 pm    Post subject: Reply with quote

When I'm running the oven inside I hardly notice the fumes. It's just the smell of plastic being warmed up. However, if you step outside the room, then come back in, you realize that it is pretty strong. The fumes are not flammable.

According to the Thurston James book, the fumes are not toxic, and are heavier than air, so they will settle down low on the floor. However, if the plastic sags too much and contacts the heating elements, then you release toxic fumes! The small amount we are working with shouldn't kill you (I had a meltdown once, and I'm still here) Just turn off and unplug the oven, remove the plastic sheet quickly, then take it outside to cool off. Afterwards, hang it on your wall to scare your friends!



Use a timer to get an average of how long it takes to heat up a sheet of plastic. As it gets close, lift the lid of the oven and check for sag, and you should do fine.

Hopefully you've got windows you can open, and I definitely recommend running a fan, two if you can (one blowing out, the other blowing fresh air in).

The charcoal breath mask would also help - I'm using an AO Safety respirator with R53HE-P100 cartridge for organic vapors...

I don't know about an air purifier, but I'm sure it wouldn't hurt Smile

And of course leather gloves! The metal frame gets plenty hot over the oven, and you need to push the plastic down on the sides and into the grooves of your buck. Just regular leather gardening / work gloves are fine.

Just like a regular shop, you are in charge of your safety!

Charlie
TI-386


Last edited by crashmann on Tue Mar 28, 2006 9:45 pm; edited 1 time in total
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jegner
Site Admin


Joined: 30 May 2003
Posts: 2144
Location: Texas, USA

PostPosted: Wed Feb 15, 2006 10:05 am    Post subject: Reply with quote

Crashman is right to be concerned with fumes.

But... It sounds worse than it is. Yes, warm plastic has an odor. Not offensive, but you know it is working. Everything I have read on Styrene is, the stuff is pretty safe. You only get into releasing harmful vapoers if you actually burn it and it starts to smoke!

We are dealing with a plastic, high heat, and close proximity. I run my machine in a tool shed. It sometimes is open, sometimes closed. But is rather drafty even closed. I do not wear any sort of respirator, as I do not find the odor offensive. The small runs we as hobbyists do, pose little if any health risk other than burns from the hot plastic.

Common sense is a good tool here. IF you are concerned about the smell of melting plastic, wear a respirator, or operate the machine outdoors. IMHO smoking causes more heath issues than vac-forming.

Good points. Safety is #1.

Jim
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GoldCylon
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Joined: 04 Jan 2006
Posts: 18
Location: Sacramento

PostPosted: Thu Feb 16, 2006 12:54 am    Post subject: Reply with quote

I have speed reading over the last three pages, and Crashman had some great pointers. I am building a table, and I am using the online guide Jim posted as my only source of help. When I reached the point to test the oven, the wire in a section lit up red and melted in less than 5 seconds. My replacemt wire showed up a few days ago, but I haven't had the time to replace it yet. One thing I need to do is read over the posting here one more time.
Thanks for the help.
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crashmann
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Joined: 27 Sep 2005
Posts: 501

PostPosted: Thu Feb 16, 2006 12:45 pm    Post subject: Reply with quote

Hi GoldCylon!

Yeah, I tend to be a little long winded when I post Razz

Wow, hot glowing red wires are definitley not desireable! Use an ohmmeter to check the resistance for each segment. The goofy thing is, you must disconnect the nichrome from the terminal posts. Otherwise, with the wiring under the table, your measuring the resistance for the entire heating element, not just from one post to another.

Make sure the terminal posts have a solid connection to the 10 gauge wire underneath, and you are alternating hot, neutral, hot, neutral, hot.

After you've verified each segment, and the connections underneath, take a reading for the entire coil. It should be 1/4 the resistance of one segment (if you have 4 segments. If you've got 5, then it will be 1/5th)

At this point, get your chicken stick and holler "fire in the hole!"

Good luck!

Charlie
TI-386
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jegner
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Joined: 30 May 2003
Posts: 2144
Location: Texas, USA

PostPosted: Thu Feb 16, 2006 1:10 pm    Post subject: Reply with quote

Sounds like all the current flowed through the one segment. Hmmm.
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