So get this, My father in law was working in the shop the other day and just finished rounding a nice 12X12X4 hunk of spalted maple on the band saw. Got it close to round, drilled a pilot hole of the screw chuck and went to mount it up. put the screw center into the vicmarc chuck and twisted on the blank, turned around to grab his bowl gouge and the blank fell off the lathe. Turns out the screw had snapped off 3/4 of the way in the blank. it seems rather unusual for the screw to break. Well I guess it is good that it feel off before he turned the lathe on! He called me to help and I ended up having to drill out the screw and luckily the other chuck we have has a larger diameter screw.