Mercruisin

i've done a little searching around the net, but i cant find anything that talks about forming lexan. i have tried searching for ther****rming, but just come up with companies that do it. i need to make some rear wheel covers for my 49 mercury body. i have a sheet of lexan, but it will have to be contoured. i sort of got the gist that you have to make a mould, and have to head the lexan up to past 200 celcius, but has anybody had any experience with this? at all? i was thinking of making a form out of some 3/4 mdf and sanding it really smooth (i hear thats what you can use for vacuum moulds). but since i cant really put mdf in the oven for a while, as it might catch fire, i was thinking about just placing the lexan over it, and using a blow torch to heat the sheet and form it around. will a blow torch cause any disscolouration in the lexan? i've tried a bbq lighter on some thicker lexan, and it didnt discolour at all. anyone who has any infomation, it would be greatly appreciated.

Dare82

My Feedback: (2)

I tried making a Lexan wing for my screwed up Subaru body and it came out a disaster. I used a heat gun and a oiled clay mold of a wing.

Mercruisin

how did it turn out as a disaster? is it just that it didnt form right? where do you think you went wrong? i just ask so that i dont have to make the same mistakes. i was thinking of using a heat gun as well, but if its a problem with that, i'll have to find something else.

BodyTuner

I would like to make custom front bumper.Any ideas on what material to use if this lexan ter****rming is not good?

Dare82

My Feedback: (2)

well...the lexan crinkled as it touched the mold. The shape was fine, but the fact that the lexan wrinkled up was pretty bad.

Mercruisin

Ok, today I tried a small peice of lexan in the toaster ovenat about 400 F. I found that if I laid it down flat, it would crinkle up easlily like Dare82 said. But I think that its because of uneven heating from one surface to the other. I took the peice out and curved it so it could stand on edge and tried it again. It heated up, and didnt crinkle. At least not until it got too liquid that it couldnt stand up anymore. I'm still gonna try with a blow torch. Though I have my doubts it will work well with that, but it's worth a try. I'll keep you all updated as I progress, and hopefully perfect a technique.

Dare82

My Feedback: (2)

If you use a blowtorch...nevermind...lets just say that it will probably change color or burn. I have not tried it on Lexan, but I have tried it on other plastics. Because I was by myself, I only had one hand to hold the sheet of Lexan. Maybe you can find a friend to wear heat resistant gloves and pull on both edges of the Lexan while you heat it so the Lexan won't crinkle as easily.

TGXnut

Try to heat up the clay mould so it has the same temp as the oven. Leave the clay in the oven while putting the lexan on top leave in oven until formed.

Don't know, but that might work

Have fun

Mercruisin

thats what i was thinking of doing. i'll still try the blowtorch on some scrap peices, but i doubt it will work right. and i definitely will need someone to help me out. "oh, little brother!"

Dare82

My Feedback: (2)

I'm still not sure about the blowtorch! It really is a powerful tool there!

FlyingV77

i saw a show, airframe art, somethiong like that... they used a blowtorch to heat plexyglass. for lexan a heat gun should work. but you need a mold, positive and nevitive, or both sides to get it to work right.

Dare82

My Feedback: (2)

Oh..I'm not sure what you said up there, but it gave me an idea. Make a mold out of clay, oil it well and place a piece of clay over the oiled surface, let it dry, then you have two piece. Put the Lexan on one and heat it, then while it is still hot, put the other piece on top to form the Lexan successfully.

Mercruisin

my sister is at an art university, so she's gonna pick me up some clay this weekend. so i'll try the oven thing. maybe even with a negative mould too. but that means i have to make two, no, four moulds. two for each side. but i need a kind of clay that can take heat and not crack. she said she would find something, so hopefully it'll all get done this weekend.

dare, what kind of oil did you use? just something like vegetable oil? motor oil wouldnt be that good i'm thinking. kinda messy, and not so good in the oven. probably not too good for trying to get off the lexan after either.

Dare82

My Feedback: (2)

I use regular vegetable oil, or any cooking oil. Just don't use too much of that olive oil, or your mom will get mad!

ThunderbirdJunkie

My Feedback: (3)

the problem with forming any sheet plastic (I used to work with a meat packing company, engineered a few of their molds) is that you have to heat it VERY quickly, and it's not really vacuum forming...there's the vacuum, but you also need air pressure on the other end-and a lot of it.
what happens, basically, is that the heating element superheats the plastic film (be it lexan, polypropylene, etc etc) to a near-liquid state, then the vacuum sucks it in, and the opposing side (very high pressure) SLAMS the plastic in the mold, then it cools super quick so it doesnt' lose its shape.
if you're doing it the old fashioned way, you're in for a LOT of work.
good luck man.

ThaMatrixHazU

I think the best technique is to vacum mold the lexan. I've been looking to do something similar to an old body. If I find some links I'll let you know. But there is a guy on ebay right now, selling an old Kyosho Optima that had a new body for it vacum molded from an original body.

ThaMatrixHazU

OH ... be wary using cooking oils. Cooking oils burn very easy. Olive is the worst, it has the lowest burning temperature of all the cooking oils. Vegetable oil is going to be your best, it has the highest tolerance.

Also, instead of clay you can use something called Sculpty, you can find it at any arts/craft store. It's easier to work with than clay and you can actually bake it in the oven, where as clay you need a kiln. After baking it is VERY hard. It's rather inexpensive as well. I use it to make chess pieces, it's good stuff. Very easy to mold. I will say though, if you use it, open the windows in your kitchen cause it stinks as it bakes!

ThunderbirdJunkie

My Feedback: (3)

why would you use ANY cooking oil?
some 5w30 would be perfectly good.

ThaMatrixHazU

I would think motor oil would discolor the clear lexan though. Whatcha think?

ThunderbirdJunkie

My Feedback: (3)

not any more than the veggie oil would.
IIRC mold release agents for the lexan are petroleum based

ThaMatrixHazU

ahhh ... this is true! plus you could heat the motor oil up substantially higher than the cooking oils!

ThaMatrixHazU

ok guys ... here's a 'how to' ... scroll about half down the page .... very interesting read

http://www.taxidermy.net/forums/Mold...43B16BF1D.html

ThaMatrixHazU

and another ...

http://www.radtrax.com/lsmold.html

Dare82

My Feedback: (2)

Well, the vegetable oil was fine when I used a heat gun. Only problem is that the heat made the oil absorb into the clay. But the Lexan still came off the mold with crinkles and wrinkles all over the place. I probably won't try this approach any more.

ThaMatrixHazU

oh yeah ... meant to mention this yesterday. Don't try to 'fire' normal clay in a regular kitchen over. Three reasons, a regular oven doesn't get hot enough to truely bake it, you really need a kiln for that. Plus, clay can release some fumes that aren't good to breath. Also, if you don't get all the air bubbles out of the clay, and try to bake it, it will explode in the oven, or kiln.

Sculpty is a good substitute if you want to make your own mold at home!