I am a visual learner so I thought this would help other visual learners. How I cut a curved windshield with a sandblaster. Starting Note: Safety First, I used new respirator, goggles, facemask, didn;t have a suit, but used a thick long sleeved shirt, with gloves taped up my arms and collar to avoid getting the media on/in me. I used this website as a guide: I pretty much followed this site and other posts here on the HAMB on how to do this, especially Brewsirs, instructions to a tee. To keep it short, I won't list every step, this site pretty much covers it all http://www.cadvision.com/blanchas/54pontiac/windshield.html I built this thing to sandblast: http://www.jalopyjournal.com/forum/showthread.php?t=270519 I bought this TAPE to cover the glass to blast the cut line: http://www.tptools.com/Product.aspx?display_id=362 Picture 1: this is a pictures of a test piece I did on a door glass, as you can see the tape really resists the blast media Picture 2: I started sandblasting and as you can see the straight line leading into the laminate, this cut took about 5 minutes Pictures 3,4,5 I started blasting the windshield, you can hardly see it but the media is etching the glass, and slowly cutting into it The windshield is an original 53, (actually 53 Buick, but its the same one) it had a small crack at one of the bottom corners, I filled it with "Zap-a-Gap" glue to keep the crack from spreading. I cut about 4 inches off the top. Media used: black diamond from Tractor Supply Company I covered both sides of the glass with cardboard. Picture 6: Frankenblaster, I can load up 200 pounds easily in here and not worry about running out. I can't give you any specific setting for the sandblaster cause your sandblaster would have different settings, the only thing I can tell you is i was running 50 psi to the gun and about 12 psi in the tank. (I know it sounds weird, but this thing is a siphon/pressure pot deal, so your running 2 pressures at once) Here is a video of the final cut and cutting the laminate <object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/kiEOR7pk4LU&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><embed src="http://www.youtube.com/v/kiEOR7pk4LU&hl=en&fs=1" type="application/x-shockwave-flash" allowfullscreen="true" width="425" height="344"></embed></object> Using the resist tape makes a great cut. This tape is made specifically for this reason. Once it goes on it does not come off, it is super sticky, but not super strong, so it goes on and comes off (when pulled really easy) I sanded the edges with 40 grit sanpaper, the good thing is that since the line was so straight, all i did was smooth down the edges as oppose to having to shape the glass The blasting took about 6 hours. Once I adjusted the pressures on Frankenblaster, I was able to go through it quicker, at the beginning I was paranoid because on another post, I read if not done correctly by using the right pressure and media it would be like throwing rocks at the glass, that stuck with me throughout the cut. After the 5th hour i said fuk it, upped the pressures (70psi at the gun and 15 PSI in the tank) and it went through it like butter, probably not a good idea, but i finished faster. I also had to give in and use masonry sand cause I didn't get enough black diamond. I ended up using 100 pounds of black diamond and 100 +/- pounds of sand (and yes I know the hazards of sand but I had no choice, TSC is not open at 7:45 pm at night ) Test Fit: I had already cut the rubber: http://www.jalopyjournal.com/forum/showthread.php?t=277772 but since i chopped the car 7 years ago without any reference points or instruction, the surrounding metal needed massaging Picture 7. This was pretty much just making sure the glass sat in right, I had to move the lip back on each side about 1/8 of an inch, it was alot of work, but without it, the glass would have rested on the sides more that the entire lip. I am still working on smoothing the metal out, I ran out of time, wire and freaking gas. Well there you have it. I am sure I missed a whole bunch of stuff, but feel free to ask questions. Rey
did you blast right through the plastic inbetween the 2 glasses, or did you flip it , and blast both sides?
i blasted one side to the laminate then flipped it to blast the other side, once I reached the laminate on the other side I cut the film with a blade
thanks, I have a 61 chev truck w/s to do soon , and I am nervous about breaking it... I hope for a first shot, but we will see what happens, thanks for all the tech, it will help.
Sorry to hear that, I know how much work this is and for it to crack, it sucks, how bad is the crack? From what I read elsewhere, if the edges were too jagged when you were sanding and the sandpaper "rolled" and broke off a piece of the glass then there could be a possibility of cracking because the jagged edges are not contained, if that make any sense. By contained I mean if the jagged edge starts to crack there is no stopping it. FWIW, when I was blasting, as soon as I got close to the laminate there were points where I would actually follow a crack, i would go over it a bit quicker and stay on it a bit longer to make sure there were no edges left over, to make sure that crack didn't spread into the glass. I know that doesn't help any, but just an fyi.
Great Tech, You got my vote! I Have heard horror stories about people buying 3 windshields and taking them to the glass cutter in hopes of returning with one windshield intact. This tech post proves that it can be done by the average builder and with basic tools. Two thumbs up for this great post!! .
That was exactly why I did this, there is no point in blaming a glass cutter for breaking a WS if the odds are against you. If, after doing all the research, and taking all the precautions, I still break it, I have no one to be mad at but me.
That tape is good stuff. Any local sign fabrication shop (not a vinyl shop) should be able to sell you some. When I was a sign fabricator we used that stuff on foam board for all of the raised lettering and borders...after it's blasted, the foam takes on a two dimensional shape and the borders and letters were nice sharp edges. Comes off easy when you peel it, but stays where you put it during blasting. I bought a roll and have only used it a few times, but it's good to know that I can use it for cutting glass now. Good tech tip & video!
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