Not a runner... but a skipper

[probreak]

If the crack has a chisel type abrupt end to it this means you are not looking at the actual end. Try probing with care and you will see the real end to your crack. You Yanks can learn a bit from we Brits. Can anyone tell me is Tony Blair really having an affair with your George?

[sgailey]

Nice illustrattion, something most trainers could probaly use. A you one anyway?

Nope.

Has anyone here tried spreading cracks on practice glass? Last week I was experimenting using pressure via the probe, creating cracks ones out of breaks and off cracks' elbows.

Just about every time, I could direct which way the crack would continue by applying pressure to the area in front of it on either side. The crack would then run the opposite way of the pressure. This trick might be useful if you're trying to direct a crack into a drill-stop that isn't directly in front of the tip.

Using this same trick, I was even able to direct a crack to turn a near 90 degrees, and then into a drill-stop that was a good six inches away. (wish I had my camera!!)

Please note, these cracks WERE manmade, and they were definitely NOT in the windshield-breaker class.

From my experience, the full-depth cracks move much more readily than say a smaller, sub-surface one--- and require much more care when applying pressure or heat. Think of trying to direct a locomotive as opposed to a Radio-Flyer cart.