Influence of Knife Edge on the Dispersion of Equilibrium Position of the Balance

Abstract

As the precision of balance depends largely upon the knife edge, the characteristics of the knife edge must be researched to improve the balance. Among researches on the knife edge only a few treat its precision. As the cause of the dispersions of equilibrium position was assumed either the rolling friction or the change of the location of the fulcrum caused by the roughness of the flat bearing. We assume that the dispersions are caused by the change of the stress distributions due to the roughness of the contact surface. An investigation was done. Standard deviation was calculated, and it was found that σ_△W was proportional to the breadth of surface in contact b, calculated by Hertz's formula, and found that the following relation existed, σ_△W=W/L·α·b