Stem Head Pressure on Large Star Breaks
Posted: July 27th, 2005, 9:07 pm
Stem Head pressure (the pressure of the injector seal against the glass) can be quite a critical issue in star breaks.
I just did a HUGE star break this afternoon and all but one leg filled nicely. I flexed the stubborn leg NUMEROUS times but just could not get the resin to flow down that leg. It happened to be a leg that was about 1-1/2 to 2 inches long, so I drilled and popped a mini bullsey at the end of the stubborn leg, then filled from that point, but the leg did not fill all the way. It still had about a half inch to go but would not go any more.
As I backed off stem pressure to the point that the injector was no longer touching the glass, the last bit of the crack started to fill on its own with the the residual resin that was either in the break, or it was resin from what was left on the outside glass. A moment or two later and the stubborn leg was completely filled with no mounting bridge or injector on the glass.
I think that since this was a quite large star break with long legs that it was naturally very sensative to stem pressure and even though the stem was just barely tight enough to keep the resin from seeping out, it was enough stem pressure to choke off the stubborn leg.
The HUGE star break ended up looking GREAT! Customer was very, very pleased and I was happy about the repair too.
Moral of the story on this one is... "Reduce the stem pressure". It could make all the difference in the world!
I just did a HUGE star break this afternoon and all but one leg filled nicely. I flexed the stubborn leg NUMEROUS times but just could not get the resin to flow down that leg. It happened to be a leg that was about 1-1/2 to 2 inches long, so I drilled and popped a mini bullsey at the end of the stubborn leg, then filled from that point, but the leg did not fill all the way. It still had about a half inch to go but would not go any more.
As I backed off stem pressure to the point that the injector was no longer touching the glass, the last bit of the crack started to fill on its own with the the residual resin that was either in the break, or it was resin from what was left on the outside glass. A moment or two later and the stubborn leg was completely filled with no mounting bridge or injector on the glass.
I think that since this was a quite large star break with long legs that it was naturally very sensative to stem pressure and even though the stem was just barely tight enough to keep the resin from seeping out, it was enough stem pressure to choke off the stubborn leg.
The HUGE star break ended up looking GREAT! Customer was very, very pleased and I was happy about the repair too.
Moral of the story on this one is... "Reduce the stem pressure". It could make all the difference in the world!