I put together some chuck data. I have seen some horrific lathe accidents over the years, including deaths. I have done several safety presentations at work on the subject as well. I don't have the complete presentation in paper format.
1. Failure modes- number one is crashes. Broken master jaws, etc. These usually don't end up injuring the operators, just the equipment.
2. Worn out/old chucks. When was the last time you bought a new chuck? When was the last time you bought a new mill vise? Same concept, but mill vises get changed 3 to one over a lathe chuck. The slides in the chucks wear out, causing unsafe holding conditions. This is usually when people get hurt.
3. Jaw extensions/pie jaws. Larger than the chuck? Think of the mechanical leverage that is putting on the chuck? Broken jaws, parts coming out, it can get ugly.
4. Is your chuck rated? A manual chuck does not belong on a CNC. They have no counter-centrifugal mechanics in them. The acceleration alone can explode them. The jaws will open at high RPM. Is your chuck rated for the RPM of the machine?
5. Having to lower your pressure? Does your chuck crush your parts? Low clamping pressures cause accidents. You need a better chuck, stock chucks dont have counter centrifugal properties.
Just think about it before something bad happens. People take lathes for granted. Imagine a 20LB part at 4000 rpm coming at your head. I've seen the end result, you won't think about it ever again!
Constant surface speed programming is just soooo dangerous on older machines.
The best safety tool is between your ears!
Why would the age of a machine have anything to do with it? Seems to me that any machine with G96 (CSS) also has a code for maximum spindle speed. That's a "G50" with a "Sxxx" command on most any Fanuc control. I wouldn't go into CSS mode without a G50Sxxx command, no matter if the machine was 30 years old or brand new!