Another crack question

[mobilerockchiprepair]

According to Glass Technologies training video, in order to stop a crack from running you drill a hole through the first layer of glass and stop at the second at a point just past the end of the crack - then run the crack to the hole. You know your through the first piece of glass and to the laminate when you feel a pop and there is no resistance anymore. This seems to work fine for stopping cracks, however I am having a problem with a grey circle appearing below the drill hole. I cannot make it disappear either. Is this a bad technique? Is there another that someone would recommend? And what is causing this ring? I heard moisture, but I don't think I am getting any in there. If I am accidently creating a bullseye when I drill through, shouldnt it go away with resin?! Thanks again, you guys have been great. Jon.

[Chips_Away_Windshield_Repair]

I can not believe G.T. has you drilling all the way to laminate.
Drill only half way down (you can check depth with blades on side of burr).
Pop bulls eye and fill.
Double check the training video!

[mrchip]

also drill about a quarter inch away from end when you drill
use a sewing needle and a tapper to make the bullseye and walk
crack to bullseye:eusa_clap

[repare-brise]

At no point should the PVB interlayer be disturbed. As described above you drill into the glass until the hole is deep enough to pop a mini bulls-eye(do a little archive search to find more elaborate descriptions on the technique, then practice it). The grey "ring you are getting is the usually caused by the PVB wraping itself around the bit. Drilling down to the laminate is not only a possible danger to the occupants of the car(creates a weak spot) but causes the unsighly blemish you describe. As with the GT technique advancing the crack into the mini bulls-eye is a prudent move(it assures you the the crack stops there, and when filling the bulls-eye part of the crack should start to fill. One aditional little tip, if when you pop the mini bulls-eye it only creates a half bulls eye, you didn't drill at the end of the crack. Some cracks are very tight at the ends(they don't apear to the eye) so make sure the point you are drilling is indeed the end of the crack(this can be accomplished by lightly appling pressure to the inside of the glass, or a quick heating of the outside of the glass(very quick, and if you see no imediate movement your fine if the heat causes a reaction continue to the end. Some techs have described a crack growing as they are repairing it, while this does happen, quite often it is caused by an "invisible" crack.

Enjoy

[mobilerockchiprepair]

I have been VERY disappointed with the information I have received from GT. However, their equipment is very good. They definitely believe in drilling and drilling to the laminate as I described. I guess they feel that is the best way to make sure it doesnt crack any further than the drill hole. I have some windshields to practice on, so I will try this new technique. It is a shame that I caused that blemish, because I DID get the crack to totally disappear... Thanks again, Jon.


P.S. HOW THICK IS EACH PIECE OF GLASS? DOES IT DEPEND ON THE VEHICLE?

[JT2]

Repare-brise is correct you should not drill right to the laminate, there is no need for that but I guess each manufacturer has there own way of doing things.

[Chips_Away_Windshield_Repair]

Jon, I think most windshields are about 1/8 to 3/16 each layer.
As mentioned above I find half the depth is appox. one half the depth of bur blades.
Practice and see what works best for you.
I'm going to try a needle although what works really well for me is after a .024 bur gets dull I knock the blades off and use the remaining shaft as it is a smaller diameter and won't chip glass surface.
By the way, different strokes for different folks I guess on techniques I suppose. Delta suggests using their blue plastic suction cup remover for "tapping." It is just too light for me. I like something heaver, a little oomph(?)(spell check please Jeff) to it and use a small LED flashlight.......perfect bullseyes 99.999% of time.

[GlasWeldTech]

I would caution everyone here to NOT use the word DISAPPEAR!!! The only way to make a repair or a crack DISAPPEAR is to change out the windshield. I mean think about it-you are working on an already damaged piece of glass and no matter how good you are and how good the repair turns out, the customer may think it disappeared but to the eyes of a good tech there will ALWAYS be some SCARRING. I am not trying to rain on anyone's parade here but to protect them from an unhappy customer that says it didn't disappear totally. Hope this helps someone here and I do love this business. I always tell my customers that there will be about an 80% improvement knowing that it will really be about a 90-95% improvement and they are happy. I tell my crack customers that if it goes well and they have been honest about it being a new crack and not rained in it,etc. that the repaired crack should look like a piece of hair inside the glass.

[maxryde]

Excellent description on popping a mini guys and the description of where the crack ends is an important piece of info tooYvan, I drill to different depths according to the situation. If the bull needs to be larger then I will drill shallow a larger bull will catch a run that wants to go around a smaller bull what I mean is if it is in a curved place on the shield and stable enough then a larger bull is called for where a smaller one is necessary in a situation where the crack has the potential to run when you tap a bull then a light tap is required, smaller is easier to hide also. IS THIS MAKING ANY SENCE? Oh well happy new year all and happy repairing too:)