stopping cracks

[PortMerc]

-practice windshield-

tried to stop a crack today. Drilled down 2/3 of the way through the first layer. Made a bullseye, the crack jumped all the way through my perfect bullseye and extended about 1/8 of an inch out the other side. Suggestions? I was thinking that maybe I didn't drill far enough down, made the bullseye, and the crack ran underneath....

[Roo]

You need to drill about an 1/8" in front of the end of the crack. You need to look at the crack from many angles because sometimes you think you are at the end from one angle and you are not. Take a sharpie and mark what you think is the end then look from other angles to determine if you are indeed at the end. Drill about an 1/8" away from end of crack and when you pop the bullseye the crack should run to the bullseye and stop. Good luck!

[Windshield Doc]

Roo is right. Get your probe and open up the crack a little about an inch back up the crack. Don't press too hard. This will help you see where the crack really ends

[Nomad]

Sometimes a crack is just plain unstable. You might chase the thing with a line of holes clear across the windshield. Here's what I do if the first hole and bulls eye doesn't work.

I inject the hole I made as normal and fill the crack as if it had not jumped past the hole. Try to get the resin all the way to the end or very close to it. Tab and set up, allow extra set up time to make sure it is bonded well and stabilized. Keep an eye on the end of the crack while doing this to make sure it isn't traveling. If it does continue to run, back off with the injector close to the end (remove it) and fill the rest as well as you can without disturbing the end that is running. If you don't panic you should be able to get the thing so it doesn't run when you drill again.

Repeat drilling and tapping bulls eye off the end of the crack, it may now be so stable that it doesn't run into the hole. I use the slide hammer in this case to tap between the hole and the end of the crack and it will run into the hole and stop. Don't hit too hard. Put injector on hole and fill as normal. Even if it maybe doesn't look like it ran into the hole it will have no where to go if it goes straight except into the filled hole and bulls eye. Sometimes if things look kind of iffy, I will drill a hole and tap on either side of the bulls eye (holes should be at the perimeter of the original bulls eye) to enlarge the area so the end of the crack will be captured.

Hope this helps.

[PortMerc]

thanks, will try all of that. Yeah, I didn't really inspect to ensure that I was looking at the end of the crack. It is just a practice windshield so I was wizzing along. Should spend more time inspecting. Thanks for all the advise.

[screenman]

For a small distance like that the resin will hold it, just fill as normal just go easy. I do a lot of cracks on very large windshields and I always drill and stop the end and then drill and pop 1/2 inch in from the end, this is where I fill from, as most cracks are very tight at the end this speeds up the process and also adds strenght to th repair. Also if I cannot get right too the edge of the glass due to trim etc. I will also put in another drill and pop right quite close to that trim. This we call a cleat and when the repair opens up and flexex behind the trim it will stop at that cleat.

I must add the shield I work on start at about $1500 and go upwards so my customers are very keen on me repairing, they are also trained to get them repaired before they crack out where possible.