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OK finnally, The Lexan windshield experiment

Discussion in 'Center Of Gravity' started by Sandman, Feb 8, 2005.

  1. Sandman

    Sandman 3/4 ton status Author

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    There has been tones of talk about it but I didnt see anybody who had tried it in a fullsize chevy. Let me know if I missed one as I would like to check it out.

    I have two sheets of 1/2" Lexan that I was able to get for free. Since I really trashed my windshield in Moab at BB04, I thought it would be a good time to give it a shot. I'll weight both the stock unit and what I end up with on the Lexan side to see what happens.

    Anybody have any suggestions for cutting it? Right now I'm thinking jigsaw but the last time I used one on plastic it actually melted it to the blade and made a mess. Maybe this stuff will not.

    Right now the idea is too lay it on a glass version, clamp it in place and cut around the edges and put it on. I think I will reuse the stock gasket setup if possible so it can take some flexing.

    Thoughts?
     
  2. Resurrection_Joe

    Resurrection_Joe 1 ton status

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    There was a thread here somewhere about working plexi, maybe you should check that out, assuming tha the traits are the same (IE cutting)
     
  3. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    if its melting, slow the speed down of the saw and be patient...
     
  4. Stomper

    Stomper ΜΟΛΩΝ ΛΑΒΕ GMOTM Winner

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    Also if it is melting, flood the cut with water to keep it cool. Plastic is pretty nice to work with (cutting, turning) if you can keep it cool.
     
  5. captaininsano

    captaininsano 1/2 ton status

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    I did the Lexan windshield in one piece not too long ago on my K5. It was a bitch but I like the end result. I welded a frame out of thin steel around the windshield frame edge and one thick piece down the center for support. More pieces of thin steel go on the outside and sandwich the lexan sheet using a bunch of bolts.

    NOTE: If you go this route drill the holes in the lexan oversize to allow for flex, otherwise you will crack the sheet like me. :mad: Live and learn right.

    I made a template out of a big piece of cardboard on the old windshield first, cut it a hair big to be safe. Then bolted on one edge and work my way across. You will need help at the bends, this stuff is tough.

    I cut mine with an orbital action skil saw using a plastic blade, cut no problem.

    One thing about the lexan that sucks is it scratches real easy. It polishes out nice though with plastic polish.
     
  6. ntsqd

    ntsqd 1/2 ton status

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    First off, does it say "Lexan" or "Plexiglas" on the labeling? Those are trade names for Polycarbonate. If it says anything suggesting that it's Acrylic I would NOT use it. Acrylic does not have the shatter strength of polycarb. When acrylic shatters it does so like non tempered glass. It will cu the s$%t out of you. Another clue is if it's easy to melt while cutting it. Polycarb melts at a higher temp.
     
  7. az-k5

    az-k5 1/2 ton status

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    Certain thickness' of palstics also stretch a lot (up to 8%) from cold to hot. Not necesarrily in one day, but you put in on in feb and all of a sudden it cracks in june. I have heard that a router can be used on it with decent results. There is less heat and more material removed with this process.
     
  8. captaininsano

    captaininsano 1/2 ton status

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    I used a sheet of 3/16" polycarbonate, same as Lexan, whatever you want to call it.

    I have some pics up of the frame I made for it. Works great, wacked a tree branch at about 35 mph running a wash in Reno desert and didn't even hurt it, would have trashed glass.

    Windshield frame to sandwich the polycarbonate sheet:
    http://coloradok5.com/photos/showphoto.php/photo/2069/sort/1/cat/500/page/1

    After done:
    http://coloradok5.com/photos/showphoto.php/photo/2071/sort/1/cat/500/page/1

    Like I said before over drill the holes in the windshield a bit if you go this route.
     
  9. captaininsano

    captaininsano 1/2 ton status

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    Also about the shattering, you can't do it. At least that is what the guy at the plastic shop said, thats why nascar uses this ****, and I tried. Reason its illegal for street though is you get some really messed up glare sometimes which makes it almost impossible to see once it gets scratched. Polishing out the windshield after every trip helps a lot though.

    We tried to snap a piece in my garage, bent it over and drove over it. All it did was bend. I can't remember what the guy said it takes to actually break some, I do know it is about 300 times stronger than glass.
     
  10. 87GMC

    87GMC 1/2 ton status

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    FWIW, We use these in our race cars. To help with scraches, we put a "tearoff" on the windshield when it is brand new, then when you clean it you'll be cleaning the tearoff and not the windshield. When it gets too scratched, replace the tearoff. We usually get one full season out of one tearoff. Also, always clean the same direction, we find up and down works best. When we tried cleaning side to side, the track lights caused more glare making it hard to see at night. Also, 1/2 might be overkill. We run 3/16 and it's been hit by flying parts at over 120 mph. As far as mounting, bolted to the fiberglass body about ever 3-4 inches around the edge and has one support in the middle.
     
  11. ntsqd

    ntsqd 1/2 ton status

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    If you are refering to my post, I agree. Shattering Poly Carb takes a LOT of force. Unfort Acrylic does not and unless you know you've got Poly Carb it's not easy to tell the difference. Would hate to hear of a mistake like that when I could've said something, so I did.
     
  12. captaininsano

    captaininsano 1/2 ton status

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    Just reinforcing my love of the lexan, my glass windshield gave me glass slivers when it broke. :mad: Lexan laughed as it broke a branch off a tree going about 50mph in a wash outside of reno by moon rocks. :D
     
  13. 66ELMeano

    66ELMeano Registered Member

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    Any thoughts on "speed glass" it's supposed to have a coating on that resists scratching. The tear off idea is something I didn't think of, some good info here!
     
  14. justhorsinaround

    justhorsinaround 3/4 ton status

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    I don't know if you maybe work in a really warm place but what we did for a race car we restored is we took a stock windshield and put it on some buckets and then the lexan over that. We then took a tarp with some sand bags hangin off it. After a few days in the Arizona summer sun, the lexan formed itself to the stock windshield which made it easier to install.

    Just a thought for ya.
     
  15. 66ELMeano

    66ELMeano Registered Member

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    I wondered if heat would do it, I have used a heat gun to form plastic into a mold before. I don't think the heat gun is the answer to the lexan though, it might deform and ruin visibility. Maybe just placing the glass/lexan above a smaller, more uniform heat source like an electric heater (for those of us that live in the snow belt) would work...
     
  16. rdn2blazer

    rdn2blazer 1 ton status Premium Member

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    i did not read all the posts but in case it has not been mentioned when jig sawing use the corsest saw blade you can get. too fine a tooth will pack the scurf or the voids between each tooth causing the piece stuck there to gall to the piece thats trying to be cut creating heat that melts the plastic. you need as much chip clearence as possible with such a soft material, and yes run your blade speed slower and lots of coolent or atleast water to cool it. put tape on the surface where your jig saw base will ride so as not to scratch it too. just my .02 cents.
     
  17. skidpan

    skidpan 1/2 ton status

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    I am going to do this eventually .. i have some more use out of the cracked windshield i have now.. probally this spring ill start getting into it..
     
  18. 66ELMeano

    66ELMeano Registered Member

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    Does lexan have a chance of cracking when you trim it like plexiglass does? I would hate to mess it up.

    What material did you use for this? I would think 5% window tint myself unless I could get something cheaper :confused:
     
  19. sledheadak

    sledheadak 1/2 ton status GMOTM Winner

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    airplanes use lexan or some other plastic for their windsheilds.they make a cleaner that gets rid of 90% of the fine scratches
     
  20. JK5

    JK5 1/2 ton status GMOTM Winner

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    I work with Lexan when making machine guarding. We use a table saw with a fine wood blade. There is no melting with this method. Cuts like butter too.

    The best lexan for scratch resistance is MR10 from GE.
     

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