A8 Geometrical tolerance of U. S. and Japanese baseball balls

Abstract

Japanese and U.S. baseball ball shape and seam height are measured by circularity measurement equipment. It was measured on the circumference side of the ball. Geometrical tolerance of the ball was measured with 4 seam and 2 seam side. U.S. seam height average lower than the Japanese ball about 0.23mm around 2-seam circumference. The distortion of the surface of the ball was calculated as standard deviation. Japanese ball are five balls though U.S. ball is two balls in the case height of 0.15mm or less distortion. In conclusion, the ball of Japanese can be said that 2-seams are higher than Rawlings's balls. The distortion of Japanese ball is less than that of U.S. ball.