The USBC stated that a ball has the best chances to cause a strike if the angle that it hits the pocket is 6 degrees.

This statement leaves a lot of questions in the air. How should the ball enter the pocket?
Should it hit the headpin at 6 degrees, then hit the 3? Should it hit both the head and the 3 simultaneously?

The ball would strike the head pin first. The pins are set in an equilateral triangle configuration with each pin 12 inches from the adjoining pin. For instance, the front pins, the 1, 2 and 3 pins, are set 12 inches apart forming an equilateral triangle. The distance from the middle of the right side of the head pin to the front of the 3 pin is approximately 8 inches. Since the radius of a bowling ball is 4.5 inches the ball must strike the headpin before hitting the 3 pin.

If the diameter of the ball is greater than the distance between two pins, the ball can strike two pins simultaneously.

Assuming that the ball should strike the head pin first, should it strike at 6 degrees about the center of the pin, relative to the length of the lane?

http://www.bowlingcommunity.com/b/ubbthreads.php/topics/57565/Re_Entry_Angle.html#Post57565

From that thread, is this chart:


As you can see, anywhere from 2.5 to 3.5 inches from the center of the headpin. That means around the 16/17 board.

In addition, most of today's balls are capable of achieving an even higher entry of angle - BTM reviews regularly get entry angles above 7. The higher the entry angle, it seems from the chart, the farther right you want the ball to be. Conversely, the lower the entry angle, the higher in the pocket you want to be. This is why deep inside lines with tight breakpoints often carry high hits better, and leave pins on what would be a good pocket hit from an outside line.

Why does the chart stop at 6*? I have seen people strike when coming in almost sideways to the head pin. I know I have seen people strike at about a 45* entry angle.

I'm curious to see what the best entry angle for the 1,3,5,9 (1,2,5,8 for leftys) spare would be. Seeing how those are the only pins the ball actually hits and are (as I have been told) the perfect strike pins.

That's the 6 degree angle of entry sir.

Thanks for the clarification.

Suppose I throw the ball down lane and it breaks as it enters the back end. If we use a piecewise linear analysis to determine where the ball should be aimed into order to produce the angle, we get 19 boards from the point of impact. That’s in the gutter. It’s breaking behavior can’t be described linearly, so the ball must take some non-linear path to the point of impact.

How do I determine the angle at which I am striking the head pin?

Ball tracking software is available and used by ball companies and to do ball reviews in the monthly magazines, but unless you want to invest a bunch of money and lug alot of equipment with you, you won't know what you're exact entry angle was on a given shot. What you can determine is whether your ball is coming in at less or more than the ideal angle. A ball coming in too sharply will leave solid back row pins(right handed jargon to follow). Example: your ball hits flush, but there stands the 9 pin. This is caused by the ball getting to the 5 pin flush and not deflecting over to the 9. Shallow entry will cause weak back row pins like the 7, flat 10, 8, or 5 pin. If your ball looks like it hit flush but deflects excessively off the head pin it will not carry and you'll know it's coming in shallow.