In article , Prometheus wrote:

It's strong enough- unless you're doing something really crazy, like
turning wood with live ammunition in it. Think about it for a minute-
the rotational force of the piece isn't the only thing that affects
how it's going to fly off if something breaks or is not held
correctly. Gravity has it's say as well- and from previous exerience
when I got my first chuck, anything that could possibly be heavy
enough to break the sheild drops just as fast or faster than it is
moving towards you.

The laws of physics dictate quite the opposite, in fact. To begin with, the
mass of an object has absolutely nothing to do with how fast it falls (as was
famously demonstrated by Galileo some five centuries ago).

Most heavy things will fall fast, then roll along
the floor- not shoot at you like a cannonball.

Again -- the velocity of a falling object is completely independent of its
mass.

Which direction it goes depends mostly on which direction it's moving when it
comes loose (e.g. on the back side of the work, moving upward -- it's gonna
launch!); at even modest rotational speeds, the velocity of the circumference
of a large workpiece exceeds anything that would be imparted by gravity in the
very short distance between spindle or faceplate and the shop floor.

Example: 10-in diameter workpiece rotating at 500 rpm; lathe center at 42"
above the floor.

The edge of the workpiece is moving at (10 pi * 500) inches per minute =
almost 22 feet per second -- but an object falling only 42" doesn't attain a
velocity of quite 15 fps before it hits the floor.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.