The following information details the current specification requirements for all bowling balls balls used in sanctioned competition. Bowling balls failing to meet these requirements must be remwed from competition.
If it is shown that the bowler had prior knowledge that his/her actions were in violation of this rule, the games in which the violation occurred is/are subject to forfeiture. In addition, the bowler is subject to dismissal from the the league/competition and suspension of membership.
A bowling ball shall be constructed without voids in its interior, be of a non-metallic composition material and conform to the specifications for weight, size and bal- ance. The use of minute reflective particles or flakes for decorative purposes shall be permitted in bowling ball material prwided such flakes or particles are made part of the ball at the time of manufacture, are evenly distributed in a uniform pattern under a transparent shell at least 1/4" beneath the surface of the ball so as to have no effect on the balance, and the total amount of such material does not exceed 1/2 ounce per ball.
The circumference of a ball shall not be more than 27.002 inches nor less than 26.704
inches, nor shall it weigh more than 16 Ibs (no minimum weight).
The diameter of the ball must be constant.
The surface of the ball must be free of all depressions or grooves of specific pattern,
except for holes or indentations used for gripping the ball, identification letters and
numbers, and incidental chipping or marring caused by wear.
Holes or indentations, not to exceed five tor gripping purposes.
One hole tor balance purposes, not to exceed 1 1/4" in diameter.
One vent hole to each tinger and/or thumb hole, not to exceed 1/4" in diameter.
One mill hole for inspection purposes, not to exceed 5/8" in diameter and 1/8"
in depth.
The table below shows permissible tolerances in the balance ot a ball used in sanctioned competition.
A) Maximum differences between top of ball (finger hole side) and bottom (solid side
opposite finger holes).
B) Maximum difference between sides to the right and left of finger holes, or between the
sides in front and back of finger holes.
C) Maximum difference between any two halves of ball with no thumb hole.
D) Maximum difference between any two halves of ball with no finger holes or indentations.
E) Maximum difference between any two halves of ball with no holes.
Maximum Tolerance (ounces)
+-------+-------+-------+-------+-------+
Ball Weight | A | B | C | D | E |
+-------------+-------+-------+-----------------------+
| Over 10 lbs | 3 | 1 | 1 | 1 | 1 |
+-------------+-------+-------+-------+-------+-------+
| 8 - 10 lbs | 2 | 3/4 | 3/4 | 3/4 | 3/4 |
+-------------+-------+-------+-------+-------+-------+
| Under 8 lbs | 3/4 | 3/4 | 3/4 | 3/4 | 3/4 |
+-------------+-------+-------+-------+-------+-------+
Movable devices are not permitted in a ball except that a device for changing the
finger span or size of the finger and thumb holes may be inserted provided it is locked
into position during delivery and cannot be removed from the ball without being destroyed.
The introduction of metal or any
other substance no comparable to the original material used in the manu tacture of the
ball is prohibited.
Plugs may be inserted for the purpose
of redrilling; ball. Designs may be embedded in a ball as guides or for observation or
identification purposes provided the designs are flush with the outer surface of the ball.
There shall be no interior voids and
the plugs or designs must be of similar material to although not exactly the same as the
original material out of which the ball was made; and shall otherwise comply with all
bowling ball specitications.
No foreign material may be placed on
the outer surface ot the ball.
The surface hardness of a bowling
ball shall not be less than 72 Durometer 'D'.
Extract taken from World Of Tenpin February 1995