Expert: Russ King - 11/30/2007

Question
Dear sir I have observed on several bowlers of various levels (from starters to experts) a bruies near the end of the thumb, not the tip and not always in the middle of the thumb but more often on the inside of it (mid and to the side closer to the other fingers)  One thing I have found with my little statistical observation is that this bruise is present to those with an oval ball thumbhole and not to those with round thumbholes.
Can you please expalin HOW this bruise is acquired (by what force, action, fit or other)and what can a player do to correct that.
Thank you in advance
Dora

Answer
This problem has several reasons. The first,the thumb hole is not beveled straight down but a cone shape where the top is bigger than 2" in.2.The thumb pitch does not match the release.When the person rotates too much over the ball, this changes the angles & forces bad pitches.This adds high friction to those points on the thumb.Also, the top edge of the thumb can cause this by the thumb not cleanly releasing. A too sharp an edge(needs beveling). Also a span change may be needed.

                  >>> EXCEPTION <<
      DOUBLE JOINTED PEOPLE NEED SPECIAL PITCHES

 MOST OF THE TIME, IT IS A CONE SHAPED THUMB HOLE WHERE THE TOP IS LARGER THAN THE MIDDLE.

WHEN BEVELING, TAKE THE SAME TIME BEVELING AT THE TOP, MIDDLE & THE BOTTOM OF THE HOLE TO STOP THE CONE SHAPE.THIS CONE IS EASILY DONE WITH THE BEVEL POWER SANDER.

ALSO BE CAREFUL WITH AN HOURGLASS SHAPE WHERE THE MIDDLE IS SLIGHTLY LARGER THAN THE TOP .


THE SHAPE (OVAL) NEEDS TO BE ANGLED RIGHT. ANY TWISTING OF THE THUMB AT RELEASE WILL CAUSE FRICTION.TADAYS BOWLERS SEEING OVERTURNING AT RELEASE IS NOT UNCOMMON.MOST BOWLERS EVEN PROS NEED SPOTTERS TO SEE THE RELEASE POINT.

THE BEST THING TO DO IS SEE THEM BOWL & COMPARE THE COMMON ACTIONS.
 YOU CAN CUT A FLEX PIECE OF PLASTIC ( LEAVING 1/2" SIZE AT THE TOP WITH A BEVELING ) SO THE TOP ONLY MEASURES THE HOLE . FIT THE TOP OF THE HOLE & GENTLY PUSH THE PLASTIC DOWN. IF IT GETS LOOSE, THE HOLE IS A HOURGLASS SHAPE. IF IT GETS TIGHTER, IT IS A CONE.THE BLACK PITCH GAGES ARE BEST FOR THIS TEST.

LET ME KNOW IF THIS WORKS. THERE ARE SEVERAL SPECIAL REASONS OTHER THAN THESE. BUT THESE ARE MOST COMMON.