DAW Posted March 22, 2002 Share Posted March 22, 2002 I'd like to make a rear hatch window out of plexiglass and I'd like to know if anyone has experience with this? I'm thinking I might try taking a glass hatch window (already out of the hatch), place the sheet of plexiglass on it, place a second glass on top (sandwiching the plexiglass), and hook both rear window defrosters to 12 volts for a day or so, with insulating material on the outsides of both glasses to retain heat. Futile? Or would the weight of the top glass (and maybe some added weight) together with the combined heat do something to mold the plexiglass to form? DAW Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 22, 2002 Share Posted March 22, 2002 The defroster bars will never get the plastic hot enough to allow a permanent change. When I've molded Plexiglass and Lexan, I've realized the temperature needed to be pretty high (I used an IR temp gauge to check this when I did it, but I can't remember what the threshold temperature was when the plastic would finally bend permanently). It should be an electric heat source too. Gas sources exhaust biproduces can and will ruin the plastic (it caused a bunch of small bubbles on a piece it worked one time). My experience with Lexan is much better than Plexiglass. I used a different method of installation than you will use, but the point I'm wanting to make is that it conforms to the compound curves of the hatch very well, and with no heat used at all. This was only 1/8" Lexan, but with a convex compound curve, even this thin of material will hold up well for the broad area of the hatch window. Lastly, get ahold of ScottieGNZ. He is in the process of making a Plexiglass or Lexan window himself using a steel OEM hatch. I'm sure two heads are better than one in this project. Quote Link to comment Share on other sites More sharing options...
Georgia Flash Posted March 22, 2002 Share Posted March 22, 2002 Blueovals this is off the thread topic, just wanted to say that your car kicks A$$!!!!! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 22, 2002 Share Posted March 22, 2002 I think you should use M-1 Lexan (I think the m-1 denotes mar-guard) It will not scratch as easily. That is what they use on funny cars, pro-stocks, pro-mods,and Nascars. I researched forming Lexan and to heat form it I was told that it must spend 24 hrs @ 400 degrees in a furnace to remove moisture as it is hydro-formed. If you leave out that first step the Lexan will form tiny cracks and appear hazy after a very short time in the elements. Then you bring the temperature up from 400 degrees to what they refered to as the "slump point" and that "slump point" temperature is different depending on what thickness the Lexan is. I believe the temperatures for the "slump points" are available from the MFG. of the Lexan. (I think G.E. makes it) I cold formed my windshield and side windows on my pro-street Malibu with no problem. I believe there is a formula for the distance from the edge and spacing of the rivet or bolt holes also available from G.E. (or was it Dupont) Also I remember that the bolt or rivet holes must be larger by a few thousands to allow for expansion and contraction of the Lexan. I also belive the rivets are special in that they dont pull the Lexan down tight like a regular rivet does. You can check with POP-Rivet brand rivets for that special non-cinching rivet. Lastly if you are installing the Lexan with the origional rubber I think you should experiment by making the Lexan just slightly larger than the glass and it may cold form to the covex form you are looking for. Good luck. Quote Link to comment Share on other sites More sharing options...
Owen Posted March 22, 2002 Share Posted March 22, 2002 By cold forming you mean just lining it up and bolting it on? Owen Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 23, 2002 Share Posted March 23, 2002 Basically, yes. On my rear window, I pulled it back off a year after pop-riveting it in place, and it's retained the convex shape. A real eye opener I saw was a guy I knew replaced his entire hatch with Lexan. Put the bottom 3/4" of the Lexan in a sheet metal brake, and bent it over by about 80 degrees to copy the normal lip at the bottom of the hatch. I hazed a bit where the bend was, and it was a straight bend, but all the same, a bit astounding for this young tenderfoot. Anyway, to finish the job he masked off a square window, and then painted every other part of the Lexan the same color as his car! Up close it looked like a hermaphrodite hatch, but from afar it looked like the real thing. Too wierd. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 23, 2002 Share Posted March 23, 2002 That's an affirmative Owen on your cold form question. The reason the Lexan held it's shape on your project bluovalz was the sun and interrior heat gain had slowly cooked the moisture out of the Lexan. Quote Link to comment Share on other sites More sharing options...
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