Optimal Axis Rotation

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ubercorb77
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Optimal Axis Rotation

Post by ubercorb77 » March 20th, 2020, 10:33 pm

I read the book "Bowling Beyond the Basics" over the summer. In the book, there was a section on axis rotation and it cited a study, "Bowling ball dynamics revealed by miniature wireless MEMS inertial measurement unit." This paper can be found at http://www-personal.umich.edu/~ryanmcg/ ... ng2010.pdf

In this study, there is a section titled "Analysis of hook potential." I read this section, because it said that the optimal axis rotation was the inverse sine of (wr/v) where wr=your rev rate in meters/second and v=ball speed in meters/second.

I did not instinctively think this made sense, so I went through each equation and diagram and tried following the paper's mathematical reasoning. They were mostly correct, but they made some mistakes. The most important mistakes are that they mislabelled Figure 9 (angle gamma is supposed to be inside the triangle) and did Equation 8 wrong (angle alpha should not be equal to angle gamma). Therefore, the correct conclusion is that the optimal axis rotation is the inverse cosine of (wr/v), whereas the paper claims it to be the inverse sine of (wr/v).

I made an online calculator for this, which can be found at http://bit.ly/axisrotcalc1

I'm not the most knowledgable on physics/dynamics but I think it was enough to understand the paper. I don't know if I'm correct, but I'm pretty sure I am, haha.

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EricHartwell
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Re: Optimal Axis Rotation

Post by EricHartwell » March 21st, 2020, 1:04 am

If by optimum you are referring the maximum Hook potential you might be on to something.

But if optimum means Strike potential, I am not so sure you could pick an optimum angle of rotation based on speed and revs alone.
Thinking that the length of the oil pattern would need to be factored in as well as coefficient of friction of the ball and the angle and line of play.
Not to mention the layout on the ball would also factor in.
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bowl1820
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Re: Optimal Axis Rotation

Post by bowl1820 » March 21st, 2020, 2:43 am

EricHartwell wrote:
March 21st, 2020, 1:04 am
If by optimum you are referring the maximum Hook potential you might be on to something.
I believe the "Optimal Axis Rotation" is being taken out of context here. The section "Analysis of hook potential" is about how axis tilt and axis rotation and other things affect the hook potential And using this info to generate a optimum axis location on the ball and then comparing it to the bowlers axis (PAP). So they can determine how to adjust their release to achieve a desired ball reaction.

Here this Optimal Axis Roation calucation for hook potential is based on a ball with no tilt.

Here's another thread from few years back about that Paper (which is from 10 years ago), This paper was some of the org. research for the Ebonite Bowlers ID Sensor and it's software.

viewtopic.php?f=6&t=11013&p=85532
Last edited by bowl1820 on March 21st, 2020, 4:11 am, edited 1 time in total.
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deanchamp
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Re: Optimal Axis Rotation

Post by deanchamp » March 21st, 2020, 3:28 am

I had a play around with your calculator. Thanks for the link. I set the RPM at 400 and changed the ball speed. Not sure if this is speed off the hand, end of the lane or an average, but basically the rotation increases as ball speed increases.

15mph = 47.3 degrees
16mph = 50.5 degrees
17mph = 53.2 degrees
18mph = 55.6 degrees
19mph = 57.6 degrees
20mph = 59.4 degrees

So the more speed dominant you are, the more rotation you should be using, according to the results. The more rotation you use creates more skid which essentially increases the speed dominance. Speed dominant bowlers usually need to use stronger layouts, surface and less rotation so they don't throw the ball through the breakpoint.
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Re: Optimal Axis Rotation

Post by ubercorb77 » March 23rd, 2020, 7:18 pm

deanchamp wrote:
March 21st, 2020, 3:28 am
So the more speed dominant you are, the more rotation you should be using, according to the results. The more rotation you use creates more skid which essentially increases the speed dominance. Speed dominant bowlers usually need to use stronger layouts, surface and less rotation so they don't throw the ball through the breakpoint.
I'm not that knowledgable on bowling since I only have 1.5 years of experience, so what the physics is on paper may be different from what a ball is doing in real life.

But what I see just from using physics calculations is that less axis rotation = less hook and the ball will slow down, and more axis rotation = more hook and the ball keeps more of its speed. I don't know, but in my mind I see that more rotation would create more skid/later breakpoint but would hook more aggressively overall.

Also, I am just calculating the hook force, not the boards crossed. So by my calculations, a 15mph ball may have the same hooking force as a 20mph ball, but the 20mph ball will cross less boards.

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Re: Optimal Axis Rotation

Post by TonyPR » April 5th, 2020, 2:54 am

A ball needs to slow down in order to carry, needs to get to the roll phase. To quote Mo “if the ball is hooking into the pocket you will be leaving a lot of ten pins so bring your spare ball”. In today’s game a lot of axis rotation is not needed nor desired, to much axis to isn’t good either. Speed is very important but again, ball needs to slow down to get to a roll before it hits the pocket.

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Re: Optimal Axis Rotation

Post by kajmk » April 5th, 2020, 4:38 pm

Knowing the science is indeed important. Realize that the pure science of: Tilt, rotation, rpms, speed, all affect skid and the shape of the shot.
Those variables are all affected by lane topography, lane surface lane idiosyncrasies, hills and valleys, how any cumulative games on a lane, the idiosyncrasies of the foundation under the lanes, oil type and distribution, climate control, proximity to doors, vents, types of balls used.

There are books that explain what the variables a bowler can endeavor to control affect, many are detailed in the wiki. There are also succinct annotated graphics on the Wiki, such as three phases of ball motion, speed and rpm chart, showing how matched a bowler is.

Mo Pinel has a gift for succinct explanation, look up his writings and videos.

Know what the variables you can control, affect.

It is easy to get analysis paralysis or presupposing what SHOULD BE.

The Marx Brothers summed it up well.
I paraphrase: "The Book asks you the bowler, Who are you going to believe, ME or your own eyes?".

Keep notes and a journal, connect the dots, but in the present, read and react.
Having a ball for every possible need is of course almost impossible, that is why knowing how to use different hand positions, grip pressure, speed etc is a great asset.

Stay safe ...
It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so

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Empathize

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