first failed repair

[toab]

Hello fellow techs..Tonight I ran into a little trouble with a big pit combo repair.The situation was as follows.I had to repair a combo star/bullseye with a pit that was almost as big as the injector head so before I drilled the repair and planted the bridge I put a little pit fill in the pit and cured and finished it to get a nice surface to do the repair on.I then used a small fg329 bit and drilled 3/4 to the pvb at center of star and planted the bridge and attempted repair however what I discovered was that I effectively sealed off the damage and could not get proper vac or penetration.So I pulled the bridge and used a larger burr and drilled to the pvb and tryed again. This time after 30 min of vac ,heat and pressure I got partial penetration but not a sucessful repair.The way that I was doing these before was with the large pit adapter but I was getting leakage at the O-ring on vac and pressure cycles.I think my next try will be to insert a slightly larger O-ring from stock and see if I can get a seal with the adapter strong enough to complete a succesful repair and get paid.I must master these types of repairs because this damage is quite common. 1- yes I had enough vac..28 hg .2-yes I had sufficient pressure.3-yes I was using a thin resin.4- yes I backed off the injector seal pressure against the glass.4- yes I tryed holding my probe on the offending area and tryed pushing on the inside of the glass for 20 sec bursts.Please help Guys.Please chime in Yvan,Jeff, Sneck.

[mafsu]

You had such a large pit that the pit fill resin probably penetrated to the pvb in some areas. With such a large pit I would fill with pit fill as you did. Then I would drill beside the pit and pop a bullseye. Fill from there, the damage around the pit on these is usually such that you will get resin flow around the pit to the other parts of the break. If not, repeat the process in the area that is not getting resin. I don't like multiple pits anymore than the next guy, but damage like this is severe enough that the customer will be overjoyed if you can fill it and not concerned about the two pits. To make your original pit look better, go back and drill the pit filler out after you are done. Fill with your repair resin, let cure for 5 minutes. Then top it off with pit filler as you normally would.

[mrchip]

Toab mafsu was right on target did you drill to finish??? whenever
you come across an extremely bad hit youve got to finish job
if it means a drill hole so be it a successful repair is not always
picture perfect keep trying:)

[GlassStarz]

Ive never had to do this but i watched someone else do it with great success. Probe to open the break apply thin resin in a good quantity allow to gravity fill heat inside with a match let cool heat again all the while adding a drop of resin if needed. Stick a used bit into the break pop a hole in a cure tab and apply pit resin place tab on as usual only with the bit sticking through it. cure as usual remove tab and inspect if needed use injector where the bit was should have left you access but if not the gravity feed should have put enough resin into it. pit fill the drill hole and polish as usual.
As I said I havnt had to go this extreme but watched it done this way by a trainer with good results

[Sneck]

Hello Toab,

Sounds like you pretty much did everything by the book. I also agree with the procedure that Mafsu describes.

I have had a few very large pit jobs such as you have described. One trick that did work for me once on a HUGE pit job was to drill the center of the huge pit (just to make sure you have cleared a good path for air and resin). Then drill and fill from a different area of the break where you can get a good seal. The resin went in easily because the air was chased out by the advancing resin through the 1st drill hole at the center of the pit.

There is no doubt that on a break such as this, you may have to "play" with it a bit. Use your knowledge and experience to repair it with the procedures you have learned, but don't be afraid of inventing new procedures on your own - and if you do, be sure to share it! There is nobody here who "knows it all"

It all boils down to simple physics. Get the resin in the break, and get the air out of the break. You are only limited by your imagination.

Good Luck, I know you can do it!