Combination break runs out to crack

[screenman]

That glass was way to hot before you even touched it. The weight of your shadow would have been heavy enough to crack it out.
if in doubt dry it out.

[harrellbenjamin]

Had a similar problem today.75 degrees and sunny.05 Z71 chevrolet 1500 series.I was at one of my Monday AM stops and found a pretty good shot to repair(I thought).It was a hit center in the lower center part of the W/Shield and had a a 2 inch crack/batwing type damage with a centralized inpact site with a strike blemish about the size of a drilled pit hole.Glass was in very comfortable temp range.Cleaned area so I could set up injector (Delta new style) and 3/4 to 1 turn after contact and started to fill using towell and U/V shield to hold it in place (windy).Checked it after several minutes and very little fill.Eased of injector 1/3 turn and reset.Still not filling.Removed injector and drilled / cleaned up shine on hole and just drilled very little to open up as nothing was flowing.replaced injector and set up as stated above.Started to flow and reset UV shield.After several minutes of watching /shielding fill was poor and I started vac cycle.As soon as I pulled up and set injector on vac cycle it ran 6 to 8 inchs across w/shield in both directions.What happened??? It was a pretty nasty crack but very small at the time I started.Should I have treated this thing like a longer crack and drilled both ends and pop and fill both ends before filling center?? Really set the day off in a foul way.I had mentioned before I started work to the dealer that this thing looks like its ready to run.Thank goodness he was understanding.

[harrellbenjamin]

Originally Posted by harrellbenjamin

Had a similar problem today.75 degrees and sunny.05 Z71 chevrolet 1500 series.I was at one of my Monday AM stops and found a pretty good shot to repair(I thought).It was a hit center in the lower center part of the W/Shield and had a a 2 inch crack/batwing type damage with a centralized inpact site with a strike blemish about the size of a drilled pit hole.Glass was in very comfortable temp range.Cleaned area so I could set up injector (Delta new style) and 3/4 to 1 turn after contact and started to fill using towell and U/V shield to hold it in place (windy).Checked it after several minutes and very little fill.Eased of injector 1/3 turn and reset.Still not filling.Removed injector and drilled / cleaned up shine on hole and just drilled very little to open up as nothing was flowing.replaced injector and set up as stated above.Started to flow and reset UV shield.After several minutes of watching /shielding fill was poor and I started vac cycle.As soon as I pulled up and set injector on vac cycle it ran 6 to 8 inchs across w/shield in both directions.What happened??? It was a pretty nasty crack but very small at the time I started.Should I have treated this thing like a longer crack and drilled both ends and pop and fill both ends before filling center?? Really set the day off in a foul way.I had mentioned before I started work to the dealer that this thing looks like its ready to run.Thank goodness he was understanding.

Hey guys any ideas on this one.????

[Brent Deines]

I've been thinking about this one since you posted it last night, and I have to admit I am stumped. I would not drill a 2" bat wing crack, and it sounds like you were doing everything else right.

It sounds like a very straight forward repair. In fact, from the description it sounds like a break that should have filled quite easily so I can't understand why you experienced the filling problem, especially after you re-set the bridge. Occasionally I have a repair that does not fill properly because I failed to center the bridge properly, or applied too much pressure to the break, but re-setting the bridge should have eliminated that possibility.

I also have never had a break run in the vacuum cycle.

You mentioned that you tightened the injector 3/4 to 1 turn, but you did not mention how many turns you used on the leveling screws. Depending on how you mounted your bridge, using the basic 3/4 turn on the injector and then leveling the bridge with the rear adjustment screws could put too much pressure on the glass, which might account for the filling problem and could be a factor in the crack out. It's a long shot, but it is the only thing I can think of right off hand. I was hoping others who have experienced something similar would chime in.

It's kind of hard to explain what I am talking about without a visual, but when you are working on a windshield with an extreme curve, usually older cars, sports cars, or motor homes, or if your center knob is not fully tightened prior to leveling, you may find that all of your adjustment may need to be made with the leveling screws, or almost all of the adjustment will need to be made with the injector. The 3/4 to 1 turn method works most of the time, but not "every" time. In rare cases even 3/4 turn could apply way too much pressure to the glass by the time the bridge is leveled.

I've only had a couple of repairs crack out on me. One was when I had applied too much pressure, and the other was when I put cold resin on hot glass. That time I didn't even have the piston in the injector yet when it took off. Kinda gut wrenching for sure. I'm now very careful to keep the pressure to a minimum and the temperature of the glass and the resin properly regulated. I have also had a few start to run when I was drilling the end of a crack, or start to run when I mounted my old style (regular suction cup) bridge as they require considerably more pressure to attach to the glass.

If you have pressure against the glass and you see a crack start to run, remove the entire bridge immediately. That will usually stop the run and give you time to re-group and figure out what to do next, which may very likely include drilling the end of the crack.

Sorry I don't have more to offer on this one.

[harrellbenjamin]

Originally Posted by Brent Deines

I've been thinking about this one since you posted it last night, and I have to admit I am stumped. I would not drill a 2" bat wing crack, and it sounds like you were doing everything else right.

It sounds like a very straight forward repair. In fact, from the description it sounds like a break that should have filled quite easily so I can't understand why you experienced the filling problem, especially after you re-set the bridge. Occasionally I have a repair that does not fill properly because I failed to center the bridge properly, or applied too much pressure to the break, but re-setting the bridge should have eliminated that possibility.

I also have never had a break run in the vacuum cycle.

You mentioned that you tightened the injector 3/4 to 1 turn, but you did not mention how many turns you used on the leveling screws. Depending on how you mounted your bridge, using the basic 3/4 turn on the injector and then leveling the bridge with the rear adjustment screws could put too much pressure on the glass, which might account for the filling problem and could be a factor in the crack out. It's a long shot, but it is the only thing I can think of right off hand. I was hoping others who have experienced something similar would chime in.

It's kind of hard to explain what I am talking about without a visual, but when you are working on a windshield with an extreme curve, usually older cars, sports cars, or motor homes, or if your center knob is not fully tightened prior to leveling, you may find that all of your adjustment may need to be made with the leveling screws, or almost all of the adjustment will need to be made with the injector. The 3/4 to 1 turn method works most of the time, but not "every" time. In rare cases even 3/4 turn could apply way too much pressure to the glass by the time the bridge is leveled.

I've only had a couple of repairs crack out on me. One was when I had applied too much pressure, and the other was when I put cold resin on hot glass. That time I didn't even have the piston in the injector yet when it took off. Kinda gut wrenching for sure. I'm now very careful to keep the pressure to a minimum and the temperature of the glass and the resin properly regulated. I have also had a few start to run when I was drilling the end of a crack, or start to run when I mounted my old style (regular suction cup) bridge as they require considerably more pressure to attach to the glass.

If you have pressure against the glass and you see a crack start to run, remove the entire bridge immediately. That will usually stop the run and give you time to re-group and figure out what to do next, which may very likely include drilling the end of the crack.

Sorry I don't have more to offer on this one.

Thanks for the feedback.It was an 05 Z71 1500 .The damage was about center in the lower 1/3 and look like a gravy repair.I set a bridge by 1st backing leveling screws and injector with piston removed to a no touch position.I then approximate the position of injector (not touching anything.) by pumping fixture base to glass.I then level with legs with injector about 1/8 inch from touching glass.Sometime sit takes a couple of adjustments to get injector face flat to glass surface.I then loosen injector adjustment knob on holding fixture and by sight over open injector or using a mirror or both line up injector opening center over damage entrance for resin.Screw injector untill it touchs glass and the turn approx 1 turn or a little less.Preload vacume cycle on injector and then apply 8-9 drops with eyedropper.Screw injector in until it just bottoms and holding injector with one hand set pressure cycle with other..I wait and monitor fill using UV shield w/dark towell.This is when I had problems.Cycled injector and and poor fill.back off injector untill some resin started to leak and snugged back enough to just stop resin from leaking.Poor fill after waiting.Used drill just to clean out pit and very minor entrance hole.Reset injector ,waited 5 minutes Pulled vacume and "crack..". I was gun shy all week.Good thing I do other services.Finally got it out of my system today at one of my Chevrolet /GMC Dealers today.Fixed 3 shields for him today at my last stop.As I was in the middle of fixing 2 shots on a 04 Equinox I saw a glint and and to my surprise under the road flim waas the same kind of shot /break as the one I had a crackout on Mon.GULP!!!!!! I set up bridge very gently and worked as if it was explosive(well it is lol) Set up pressure with just the weight of plunger and covered up and finished up removing tabs and pit polishing other two shots.Looked at it and the leg still looked ok .Gently pull vacume and time.reset pressure cycle and fill looked good.Let set up for a few extra .Pulled 1 more cycle ,tab,Polish.Nice looking repair. I felt good. The only thing I can think is that I may have applied pressue to the injector in a downward motion as I at the same time pulled injector into vacume cycle.I am very carefull now doing this move.

[glassdoctor]

I have seen a Dry Star crack out a break.... in less than 20 seconds. I never have understood how it rarely requires more than a single 20 second heat cycle either. Stars esp... require at least a couple heat cycles. A simple bullseye can be a quickie though.

I do pretty much the same as screenman describes.

[Brent Deines]

Originally Posted by harrellbenjamin

Thanks for the feedback.It was an 05 Z71 1500 .The damage was about center in the lower 1/3 and look like a gravy repair.I set a bridge by 1st backing leveling screws and injector with piston removed to a no touch position.I then approximate the position of injector (not touching anything.) by pumping fixture base to glass.I then level with legs with injector about 1/8 inch from touching glass.Sometime sit takes a couple of adjustments to get injector face flat to glass surface.I then loosen injector adjustment knob on holding fixture and by sight over open injector or using a mirror or both line up injector opening center over damage entrance for resin.Screw injector untill it touchs glass and the turn approx 1 turn or a little less.Preload vacume cycle on injector and then apply 8-9 drops with eyedropper.Screw injector in until it just bottoms and holding injector with one hand set pressure cycle with other..I wait and monitor fill using UV shield w/dark towell.This is when I had problems.Cycled injector and and poor fill.back off injector untill some resin started to leak and snugged back enough to just stop resin from leaking.Poor fill after waiting.Used drill just to clean out pit and very minor entrance hole.Reset injector ,waited 5 minutes Pulled vacume and "crack..". I was gun shy all week.Good thing I do other services.Finally got it out of my system today at one of my Chevrolet /GMC Dealers today.Fixed 3 shields for him today at my last stop.As I was in the middle of fixing 2 shots on a 04 Equinox I saw a glint and and to my surprise under the road flim waas the same kind of shot /break as the one I had a crackout on Mon.GULP!!!!!! I set up bridge very gently and worked as if it was explosive(well it is lol) Set up pressure with just the weight of plunger and covered up and finished up removing tabs and pit polishing other two shots.Looked at it and the leg still looked ok .Gently pull vacume and time.reset pressure cycle and fill looked good.Let set up for a few extra .Pulled 1 more cycle ,tab,Polish.Nice looking repair. I felt good. The only thing I can think is that I may have applied pressue to the injector in a downward motion as I at the same time pulled injector into vacume cycle.I am very carefull now doing this move.

Except when working on an extreme curve we recommend setting your injector first, then leveling with the rear legs to prolong seal life. Turning your injector while under pressure can damage the seal and cause it to leak.

Something else to consider is not counting your resin drops. When using a top load injector I recommend figuring out how many drops are in the dropper or syringe by first dropping the resin back into the bottle one drop at a time. Once you have established the correct level of resin in the syringe or dropper you never need to count drops again, and you can insert the tip of the dropper or syringe all the way to the seal before releasing the resin. Regardless of what type of bottle or applicator you use counting the drops usually results in most of the resin ending up in the cylinder threads, so sometimes you won't have enough resin in the end seal to fill the break properly. Although Delta Kits recommends 7 drops of resin per repair to ensure there is enough resin for any size break even on vertical applications, most repairs only require 2-3 drops of resin to fill (just enough to completely fill the end seal).

I once made a fool of myself when doing a demonstration for a dozen or so glass shops. I was used to using a dropper to load the injector, but this time used a plastic squeeze bottle and counted my drops. The break would not fill properly for anything. Luckily one of my customers was there to point out the problem. I went back to using droppers and never had the problem since. Your new Delta Kits injector has fewer inside threads and a larger diameter cylinder than the old style, so losing resin in the threads is less of a problem than it used to be, but making sure you insert the needle or dropper fully in top load injectors always saves you resin and helps fill your breaks completely. It also helps keep resin mess and waste to a bare minimum.

You may already be loading the injector correctly, but we see technicians making this simple mistake all the time so I thought I would throw it out there.

I'm glad you got your confidence back. A crack out definitely makes one a bit gun shy, especially when you can't figure out why it happened. Sometimes a crack is just extremely volatile and wants to run, but luckily it is a rare occurrence. It may very well be that you did everything correctly and this one just had a mind of its own.

[harrellbenjamin]

Thanks for the advice.I will set my injector first and the legs from now on.I use a dropper that I know approx the number of drops at a specified level.If any thing this made me more carefull.