A steel ball, the target mass = 2.6 lbs, the diameter is set between 1.0" to 3.0", to search its feasible diameter. Whatever you change the running preferances and convergent error, it stops at diameter 1.706", mass is .736 lbs, which is totally not feasible answer. The right answer is: diameter 2.60", the mass 2.6 lbs. I don't know what is wrong on my calculating. but, the result is totally not reliable. Does anybody have the same prolem as mine? Thanks, TZ