How I Cut the Curved Glass Down on a Chopped '55 Chevy Pickup

First of all, I'm a Glassman! Here's a link to my thread in the Hamb O'Dex...

http://www.jalopyjournal.com/forum/showthread.php?t=614524

Thanks for takin' a minute to check that out. Now I'll get to my tech article.... I'll try to explain how I went about cutting and installing the curved windshield and big backglass on a fellow Hamber's ride! He was kind enough to bring the job to me clear from Vancouver BC and he said he's had people tell him this couldn't be done, and I know there's a lot of mystery around the subject of cutting curved glass, so I'd just like to explain how I do it and hopefully debunk some myths and open some imaginations while you fellas are fabricating your customs and chop tops.

As you probably already know, cutting curved glass as opposed to flat glass is a lot different. For starters, when glass goes through the process of getting curved or bent, there is a lot of heat involved and it gets into a molten state and then curved into the mold. I'm not a physicist, but for whatever reason, the glass cools in such a way that it is under some tension at the curved areas. I believe its loaded up with kinetic energy. When the glass gets scored by the glass cutter, it begins to release some of that tension and it winds up breaking away from the score, that is why a lot of people have a hard time cutting curved glass. Over the years I've somewhat figured it out though, and I've come to the conclusion that its really not too hard if its done correctly. The way ya line the cuts out in the beginning makes a big difference in the success ratio. And even with quite a bit of practice, i'd estimate I'm only in the 80%-85% success range. With that being said, I am always clear with my customers that I might be able to do it the first try, or it could take me 2 or maaaaybe even 3 tries before I get one that breaks right for me. I can't afford to eat all them busted windshields, so its the customers risk.

The first thing I did on this '55 was get the new glass up there and start with some rough marks, for my first cut. I needed to take some off the top of this windshield to even get it to sit down close to the pinchweld because of the overhang on the front edge of the roof. I made my marks with a Sharpie marker and left it big on purpose because its pretty easy to grind excess glass off, but even after all these years I haven't been able to come up with a way to stretch it yet. I knew I had to cut the rubber gasket and take some excess out, but I wasn't sure exactly how much. On this particular truck, the windshield gasket has a big ol' flap on the inside that goes up the sides and across the top, but not along the bottom. In order to keep the bottom without having the flap, I had to make my cut and take the excess out at the very top of the gasket, right in the middle. Otherwise I always try to make the splice at the bottom right in the middle. I use a cheap PVC pipe cutter to make the cuts, so I can make nice clean straight cuts. So I looked at the profile of the gasket and its apparent that the glass sets on the outside of the pinchweld and rides about 1/8" bigger than the pinchweld itself. That gives me a reference to where the edge of the glass needs to be in relation to the edge of the pinchweld.

After makeing my preliminary marks, I looked at it and decided I only needed to make a cut across the top of the windshield. Everything else was not taking enough off to make a cut, so I used my seamer and ground off everything other than that top cut, after I made the cut.

To make the cut I use my trusty oiled cutter and my drop-jaw glass pliers, pull up my pants and getto cuttin'. The oil in the cutter is wicked onto the cutter wheel to lubricate and cool the score. Its hard to explain how a good cut is supposed to be, but ya can't make it too light or too hard, or you're screwed. Also notice I didn't make my cut follow the curve on the top corners, I ran it straight out. That's because of the tension thing I was saying earlier. Also keep in mind that since the windshield is made with laminated glass so ya hafta score and break the inside pane as well as the outside pane. I always start with the outside pane first. Once I've made the score, I immediately grab my pliers and start to make the break by prying down, and always staying behind the leading edge of the break with my pliers. You want to "run" the break, and I start in the middle where the windshield is almost flat and work my way out to each end. I start in the middle because I have more control of running the score where the glass is flat and not under as much tension as it is out on the ends where its really curved.

Once the outside pane is broke cleanly, I flip the glass over and do the inside pane the same way. Going very slowly and with great precision I score right over the top of my first score, and the score will break clean without any stray cracks. Once it is broke clean on both panes you're home free. I then pour some Glassman's Special Sauce (denatured alcohol) over the score and light it on fire. It'll burn a nice little orang and blue flame all along that break and the point of it is to warm that plastic up that's between the two pieces of glass to a point where you can bend the cut piece down enough to get a razor blade in there to cut the lamination. It may take 2 shots of fire to get it warm enough and you don't wanna get it too hot either. If ya can't touch it after the flame burns off its too hot.

Once I have the big stuff cut away, the rest is done on my seaming machine using brand new 60 grit belts, wet of course, and I just keep whittling it down till it fits like I need it to. I didn't count how many trips back and forth to the seamer I made on this particular windshield, but i'd say at least 20, maybe 25, and I felt like I had wrestled a grizzly bear all afternoon by the time I got home last night. Its a lot of work throwing that big old heavy ass windshield around all day! I used several new belts to get it into shape too, but its too risky to cut anything under about 1/2", so that's why I like to use the seamer.

Now once I have a size and shape I'm happy with, I put a little bevel on the edges for an easier install and use the Ancient Indian Rope Trick and go about installing it. It should be noted that even this truck took me 2 tries. I actually cut 'em both first try but the first one was still just a tad too big and I got a little western with it when I was installing it and the SOB cracked while pulling the last 6" of rope! The shaded one is the 2nd one, which turned out great!

I'll be doing the backglass in the next couple days and will follow this thread up with some in.fo on that. Feel free to comment and ask questions! I'll follow along and if I can help anymore of ya out, let me know!!

 

Hi Chris, this reminds me of the good old days in the Auto glass business. Only once did I take on chopping down a windshield for a '55 chevy, it took 3 windshields before I was successful. Curved glass is so unpredictable. I grounded down the cut edge on a water injected belt sander like the one your using. I used to do production laminated cutting for Case tractors and some for Crane companies. I could, back then, cut lami. in my sleep.

 

I am amazed at the voo doo you do. I know of several chopped cars that were abandoned because nobody knew how to cut the glass. I'll be seeing you again one of these days for glass in my 57 Ford panel truck.

 

So how much is that roof chopped? Any decent side shots of the cab?

Thanks for the effort!

 

This is the best one I have but I can get a better one tomorrow. I also made a paper template and will lay it on a new stock windshield to show what and where I removed glass. This chop was about 2" by the time it was all said and done, and was not quite symmetrical, but is one of the best chops I've ever seen done! The metalwork is top notch, as you can't even really tell where it was cut at all.

 

That is amazing! Not just the cutting but making it fit,,cutting a curved windshield with anything is a chore,,did one for my boat however I was using Lexan so plenty of room for error and no chance of breaking it but getting it to fit, what a challenge,,

 

I've heard of cutting curved glass with a sandblaster; apply several layers of tape below the cut line & blast away. Any experience with that method?

 

Chris, well written report, been cutting windshields for 47 years. I still use the "I can hold my breath longer than anyone in the room method" I would not steal your thread but would like to expand a bit on a few of your points.

if I lose a windshield I find a different brand or manufacturer. AGP is my absolute least favorite. I've only lost one out of the last ten Chinese windshields (I hate saying that.) Viricon, PPG (now made in china) LOF are ones I search for.

when running with pliers I wrap the flat jaws with a couple rounds of electrical tape. give me a little slack with curved glass. and I always go back over my run 2 -3 times sometimes you watch the light in the run. sometimes it's hard to get enough pressure on the break, it only goes part way thru the break. I've lost more than a few with a sneaker thru the run that was not complete. another thing I do is a series of relief cuts every 6-8 inches allows me to take off smaller sections with the alcohol without stressing the whole cut.

20-30 years ago the manufacturing and quality were better than today. the glass was thicker. many of todays windshields are very wavey near the edges almost looks like they use paddles to help the glass sag in the ovens. it's easier to take 3 or 4 inches than 1 or 2. when taking off off thin strips I like to take a loop (like cutting a mails slot in a store front) then work short sections across the top the grind the tits off

one quick note 55-59 trucks depending on the chop you would be shocked on how well the D-394,D-396,D-512, D-513 fit in place of the D407

 

Chris is giving you good information. I've written several threads and it always ends with sand and tile saws. if you do a search on other methods it has been covered many times.

 

Those are all really great tips and points! There is definately an art to doing this kinda glasswork! I honestly think that's why I enjoy it so much! To me, its like a "lost art". I can't think of much i'd rather do than fiddle around on hot rods all day!

The vintage curved glass I've been using is offshore stuff that my buddy started bringing in for me on his containerloads, and I couldn't be happier with it! (I hate saying that too) they're FYG brand the quality is better than any I've seen since you were still able to get OE ones. They're thick and heavy and just have great shape, shine & clarity.

I've gone so far to save chop jobs as to use a new windshield out of an early 90's Toyota Corolla and cut it down to fit into the backglass on a chopped '52 chevy styleline that the chop was great except the originaly backglass wound up being too 'bubbly' and made a funny roofline. Took me hours and hours of looking through 20' tall pegracks full of loose windshields, and envisiong the size & shape of the roof on that car till I finally found one I thought would work

 

I do one or two a month, I take the stock backglass and lay it on w/s till I find the curve that fits, also have used some tall windshields to match the curve of side windows for late model chops.
Just cut down a laminated back glass for a chopped 51 merc. able to get the window standing close to stock with a 5 inch rear chop. I don't advertise but stay busy 12 months a year. doing nothing newer than 1970.......Jim

 

I never forget my first cut back glass 1966 had a 1952 Cad right side of the 3 piece back glass. wasn't available. took the left side out and found a 60's chrysler windshield that had a heavy wrap and cut and installed it for $35 (the 5 was what we sold used windshields for)
I haven't a clue haw many hundreds I've done but remember I did 19 before I lost one

 

Awesome thread! Thanks guys!

Chris, stop by on your next time through!

 

Thanks. These trucks are almost always chopped too much when chopped. I've always wanted to see one with a one to two inch chop.

 

A man that can cut glass like that has my deepest respect, a man that does it whilst smoking is a god.

 

Thanks for posting this!

 

My 7 year old daughter Bella was tryin' to get a pinup spot in the "installed" pic, zebra coat & all, but I couldn't talk her into standing beside the truck, she was ok with bein' behind it lol she'll be the next generation of hot rod glass cutters here in a couple more years! She already likes to make herself useful when she's at the shop with me! She also was the photographer for my sanding action photo!

 

Chris, I would call you a "Craftsman"

maybe i missed it but how long did it take to cut the glass and about how long to fit n finish the edge ?

 

I'll be posting a couple videos later today of me cutting the backglass!

 

I'll be posting a couple videos later today of me cutting the backglass!

 

Im a retired glass cutter, that still has all my tools, and I do a few jobs, now and then.I cut the windshield in my 60 starliner, after the top was chopped.This is the first post about cutting curved glass, that is explained very well, and in terms, the average guy can relate to, great job!If I've learned anything about glass, its this, you will never have a 100% success rate, too many varibles, relax! glass can sense the nervous tention! Make staight cuts, and take off small amounts, it takes time and patience.

 

Chris, Good job on explaining.

 

Here's a quick video of me hackin' the top off that backglass. There's another video on my Youtube channel there that shows me scoring and breaking the glass first, if you want to check that out too, but this one gives you an idea of how it's done!

http://www.youtube.com/watch?v=dBMeCxLfzE4&list=UUIw1sPEDxT3s_irRd_e-c3A&index=1&feature=plcp

Have a great weekend ladies & gentlemen!!

 

Backglass installed and she's ready to head back to BC! Can't wait to see the pics when this truck gets finished up!

 

Awesome work Chris

thanks for the look into your world

 

That chop looks real subtle. I sure would like to see what it looks like with the whole body together. And thanks for the pics!

 

Looks good Chris

 

very impressive chris! you guys that have the patience to cut that curved glass wow!

 

Thanks
Good tutorial i think ill go out and start cutting some glass again