OK, the chuck jaws have a given mass (measured in either kg or lbm) and a specific *center of mass* (also called *center of gravity*). If you have these to values, the acceleration they undergo is given as *a = v²/r* where *r* is the distance in m or inches from the center of the spindle to the *center of mass*. *v* is the rpm of the spindle * *r* * 2 * pi / 60 and will end up in either m/sec or in/sec. Thus, your acceleration ends up as: *a* = 4 * pi² * rpm² * *r* / 3600.

1 lbm X 1 g = 1 lbf. Thus, if you are using lbm and inches, your force per chuck jaw will be: *F* = *ma* = (M lbm * 4 * pi² * rpm² * *r* / 3600) / 386.09 -- where 386.09 is 1 g in inches/sec².

The caveat here is that though a kg is *supposed to be* a measure of **mass**, the unit kgf, which is 1 kg X 1 g has become quite common in recent years and, if your measure was in *kgf*, then the acceleration needs to be divided by 9.807 m/sec² to turn it into a measure of *gravities*. I work with a number of European-based companies that regularly supply "mass" values in kgf -- and often do not distinguish between **mass** and **force** which leads to major confusion (especially as the "proper" measure of **force** in the metric system is that worthless measure the *Newton* -- which is why the *kgf* has come into usage)!