Rev Rate Calculation Question

[bobforsaken]

I've seen the way of timing how long it takes for your ball to go down the lane and then calculating the rev rate based on how many revolutions occurred during that time.

http://powerhousebowling.com/images/...rate_chart.pdf

My confusion comes from the actual counting of the Revolutions. There is the initial side roll you impart on the ball rotating around your PAP. When the ball finally enters the roll phase, the ball is now rotating around its Pin, Right?

It seems the Roll phase completes a revolution along the axis of the Pin faster than the revolutions originally imparted along the PAP. So if you are to count all the revolutions of the ball during its trip down the lane to get an "average RPM" then you could increase average RPM simply by throwing it in the dry and letting the ball roll out sooner.

This line of reasoning really makes me think of that method of calculating revs very suspect. Am I missing something?

I took a video from this afternoon filmed at 1/8th regular speed. Timed how long one revolution took place from my hand= t. 60sec/(t/8)=RPM's Seems like a truer way to calculate the RPM's you are actually imparting on the ball.

[Shaneshu87]

i just put a piece of tape on my pap set my camera to high speed and launched, i was taught to count how many rotations you see in the first 2 seconds, then average the two and times by 60 to get your RPM. i did this with my cell phone my rev rate is 325ish lol i forget the decimals now

[bowl1820]

I've seen the way of timing how long it takes for your ball to go down the lane and then calculating the rev rate based on how many revolutions occurred during that time.

http://powerhousebowling.com/images/...rate_chart.pdf

My confusion comes from the actual counting of the Revolutions. There is the initial side roll you impart on the ball rotating around your PAP. When the ball finally enters the roll phase, the ball is now rotating around its Pin, Right?

It seems the Roll phase completes a revolution along the axis of the Pin faster than the revolutions originally imparted along the PAP. So if you are to count all the revolutions of the ball during its trip down the lane to get an "average RPM" then you could increase average RPM simply by throwing it in the dry and letting the ball roll out sooner.

This line of reasoning really makes me think of that method of calculating revs very suspect. Am I missing something?

I took a video from this afternoon filmed at 1/8th regular speed. Timed how long one revolution took place from my hand= t. 60sec/(t/8)=RPM's Seems like a truer way to calculate the RPM's you are actually imparting on the ball.

The Powerhouse chart is just the overall average rate as you've seen. And yes when the ball enters the roll phase, that's when it makes Max. rpm.



And yes the overall is not as accurate that's why The Rev rate that you need to concerned about is the off hand rev rate, that's measured in the first 15' of the lane. When they ask for bowlers release spec's that's the one you try to give. (The overall will do if that's all you have).

Calculating Rev Rate requires a video.

Place Tape from PAP to above fingers.

Make sure the tape is contrasting in color to the ball. This will allow you to easily see the rotations.

Film a few throws

TAKE NOTE of the Frames Per Second you're recording in. Most video cameras are either NTSC-30FPS or PAL-25FPS, but other rates do exist.

On a frame-by-frame player (Quicktime) count the number of times the tape revolves over 10 frames. Be as exact as possible with this calculation.


1/4 rotation over 10 frames is equivalent to 45 RPM, so a minor mistake in reading the video can be large
To minimize error, throw more than one shot, and average your results.
The higher the video quality, and the higher the frame rate, the more exact results you can obtain.


A short duration such as 10 frames is best, as this allows you to remove many effects of the lane such as friction.


You will end up with X Revolutions / 10 Frames

At this point, it's simply conversion factors from high school science class:

I am using 30FPS, as most video cameras in the US will use this *


(x Revs / 10 frames} x (30 Frames / Second) = (revs / Second) (Revs / Second) (60 Seconds / 1 Minute)


Multiply X Revs by 3, (or multiply by 30 and divide by 10) The Multiply your result by 60. It's pretty simple!


For example: If the ball Completes 2 FULL rotations only over 10 frames

2/10 * 30/1 * 60/1 = 360RPM

Example video:

[bobforsaken]

Excellent.. thanks! I suppose since its still skidding in the first 15 feet I could count the revolutions reached as it hits the arrows and multiply by 4 to get the total revs I would get if it were to travel like that (no hook/roll) for a full 60 feet and use the powerhouse chart. I have a slow mo speed on my camera but I don't think I'd be able to advance by frames.


Any.. thanks for helping me understand.