Not sure where else to put this, but since it's fabrication...

I'm trying to find some sort of plastic (clear) to make a headlight assembly out of. Maybe something in a liquid form that I could pour into a mold and bake. I don't know what's out there, much less where to find it. If anyone has any ideas, please feel free to chime in.

 

I got my hands on some plastic pellets used for injection molding, so I'm going to try them. Anyone have any ideas on what to use for a mold? Those pellets have to be heated to around 400 degrees.

 

ive heardof people using aluminum foil, and expanding foam (like great stuff foam). make a block with the foam, and carve uo the desired shape. then line with foil (although that might not work well for your application) and pour in said pellets and voulah!! a headlight lens!! or a melted pile of pellet goo in a box.

 

I might give that a try. I got the pellets for free so I won't really be out any money. Where can I get that foam you are talking about?

 

I don't mean to badger anyones advice or anything but if you use a foam mold lined with foil it will give you a nasty rough part. Your plug (what you are making the mold off of) needs to be as slick as possible. If it is an oem headlight lens just make sure is is clean of all debris and such. I use paste waxes on most of my smooth molds and pva on my rougher molds.Wax is normally a better mold release. You will need to have a nice even coat of wax or pva whichever you choose on the plug so you will have a nice even release and have a nice smooth mold. You can use urethane foam as a mold as well but will need to use a filler after it has been pulled off the plug so you will have a smooth finish. 2lb. denisity foam can be easily sanded and worked. It is normally the density of choice when using to make molds and such. If this is a one shot deal where you will not be making more than one set of headlight I would just use fiberglass (polyester resin) for your mold. If you will be trying to small scale mass produce them for sales fiberglass won't stand up to the heat and abuse of heating the plastic as well as epoxy will. Epoxy resins are far superior to polyesters. Your standard 1.5oz fiberglass mat will do fine for your mold or a woven cloth. Fiberglass cloth will be more durable and you can use it with either resins as well. Another route that you might look into is lexan or just plain plexi glass. I know alot of the windshields and landing light covers on the Cessnas, Pipers, and other small aircraft work on are one of the too,and many times all they do is use a sheet at a time, heat it up,bend and press it into the mold. http://www.uscomposites.com/ Us Composites should have eveything you need to get the ball rolling is you have any questions just let me know. I may not know the correct answer right off hand but I'll be sure to find it.

 

xtreme you rock! That does answer a lot of my questions. I just want these lenses to be crystal clear and smooth. I'll check out that website and see what they have to offer. Can you take plexi or lexan and heat it and bend it? Will it not hurt the look or structural integrity of it? If that works, I may be better off getting some of that and heating and bending it to the size I need...using that as my actual headlight lens.


edit: If I'm going to do the mold thing, I need something to pour into the headlight pocket, and once dry, make a mold of that.

 

Ok, what kind of vehicle are you making a headlight for? There will be draw back to both lexan and plexi. They both will scatch fairly easily and over time plexi will fade and fuzz over. Do you plan on this vehicle sitting in the driveway or in a garage somewhere while not going down the road? If in a garage plexi should last just fine. Sunlight kills it faster than anything. You will also have to be carefull what you use to clean them as well as that could harm them too. Lexan is going to look crazy expensive next to plexi so for starters i would try the plexi glass. As far as heating them and bending them yes i know you can with plexi for sure. I am pretty sure you can with lexan. There are two different kinds of lexan and I don't really know much about their difference other than one doesn't scratch as easily as the other. Here is another website that may be helpful.http://www.modernplastics.com/custom.htm

 

What were you trying to ask when you said that you were pouring something into the headlight pocket?

 

Again xtreme, thanks for your help. For starters I'm doing this on a thirdgen camaro. The car will be parked in a garage always, except for occasional street and race use. About pouring stuff into the headlight pocket: If I poured plaster or foam into the headlight pocket and let it dry, I could remove it, smooth it, and make a mold of that (since it would be the shape I need)...or am I wrong in doing it like that? Basically I want to make something like the breathless kit for the trans ams. I don't like those headlight pockets (not to mention they trap tons of air), and I want to be able to use HIDs in it.

 

You can use either foam or plaster I have used both before. But being that you will be using heat and pressure to form the plastic around your mold I probably would try plaster.I would go ahead and use body filler and primer to slick the mold out then paint it. You might want to make another mold just opposite of that one(like on the front of the headlight lens) so you could use it similar to a press that way you would have a smooth finish on both sides. I feel it would make the working process of the plexi or what not alot easier. As for heating the plastic I would get a good heatgun. Snap on sells a dandy one but they are fairly expensive.

 

I have a pretty good heat gun...it's not snap on, but still good. So do you think I should try laying some plexi on top of the mold and heat the plexi to form around the mold? Also, what kind of plaster should I use?

 

I talked to my boss last night and he said that he has actually bent lexan in a sheet metal brake before and conforms nicely when heat is applied. Lexan is also pretty much resistant to anything other than solvents and fuels. As far as plaster goes it really doesnt matter. You should be able to get some at any larger craft store such as Michaels if you are familiar with them.

 

Yea, we have a Michaels here...I'll check them out for some plaster. That's good to hear that heating lexan works well. I think I will try that first. It looks like the link you posted above has a super nice selection of lexan. Piece I need should only cost around $30, so even if I screw it up, I'm not out much. Thanks again for all your help!!

 

Not a problem at all. Just let me know how it turns out and send pics if you would.

 

It will probably be a little bit before I do it, but I will definately post pics when I'm done.

 

I forgot to mention the other day that another supplier for lexan is VFN they are a sponsor on here.

 

I'll check them out...thanks again. I just started painting a 68 firebird, so it's going to be a little longer till I get a chance to do this.

 

Anyway I see it you are going to have to wet sand, polish, and buff it to clearness anyways. Even if you use wax like in an investment cast.