What's going here?

[nnam]

If this is happening, I would say that your jaws and scroll or screws are too loose and you have a problem with your chuck.

All metal working chucks that I've used move smoothly and solidly, they are just not going to rattle loose.
Even the woodturning chucks I've used (always scroll chucks, usually the jaws are loose enough that they flop around if nothing is in the chuck) just wouldn't be able to rattle a jaw loose. Most have pin that prevents you from winding the jaws all the way out without removing the pin.

I could see a 4 jaw chuck being out of balance at higher speeds when the jaws are set differently, but you never run so out of balance that everything is jumping around.

I should also have said that spinning an empty chuck for any length of time is rather pointless!
Anytime I may have run an empty chuck it would have been briefly to check something else out (i.e. carriage / cross slide power feed or lead screw engagement).

Anyhow, it sounds like I haven't missed out on a major safety warning. Unlike the other day on this forum when I learned about a drill grabbing thin brass or acrylic sheets and ripping them out of a vise leading to a potential finger loosing event!

-Dave

I was guessing only. Who would spin it for so long. But I think it does have a point. What if the jaw was open wide enough. I did accidentally opened it wide enough to clamp a large part to the point the jaw failed loose. So I think it's like people saying put safety glass on. It doesn't happen often, but when it does, it's pretty bad. Well, it's all guessing

 

[higgite]

At the very beginning there is a text warning on the video that says "never run an empty chuck" - while this is something I wouldn't be inclined to do, I have on occasion done it (wood turning and metal turning). What's the thinking on why this is a no-no?

I could see maybe a jaw might not be engaged with the scroll, but that's not really an empty chuck problem, it's a jaws are too far out of the body problem.

Thoughts?

I may be wrong, I was once before , but I don't think it has anything to do with throwing loose jaws about the workshop. One reason I can think of right off hand to not turn on a lathe with an empty chuck is with it turned off there's no chance of grimlins starting it while you're inserting a work piece or torqueing on the chuck key or tightening the collet nut or what have you. Not a bad safety tip really. ymmv

Tom