No local tournaments this weekend, so I finally got around to taking some video to calculate my current rev rate, axis rotation and tilt, before making any major changes to my form or release.



The video was just under 6 seconds at 1/8 playback speed, for a total of 0.7 seconds. During that time, I counted 3 full revolutions of the ball. So, if I am calculating correctly, (3 revolutions / 0.7 seconds) * 60 seconds = 257 RPMs.

I also snapped a photo from the video at the point of release. I am just guessing, but it looks like around 80 degrees axis rotation and 10 degrees axis tilt.

Does that appear to be correct?

Another calculation...15 feet in 0.7 seconds = 21.43 feet per second = 14.61 miles per hour. That sound right?

Do you have a higher resolution version of the image of your release to use the overlay for tilt and rotation?

If you know the FPS of your camera you can use this to calculate the speed: http://www.insidebowling.com/coaching/releaseCalcs/quickCalculator

Thanks for the tip. Unfortunately, that was the best shot I could get from my entry-level video camera at 60 fps. Movie Maker was helpful in calculating the fractions of seconds.

Using the overlay I came up with:

82* of rotation

12* of tilt





If you have a higher resolution image that is more directly behind I can try to get a more accurate reading. It was a little hard to see exactly where your pap mark is.

Thank you, B-Hammer! That was exactly what I wanted to do, to combine the photo with an overlay. I just did not know how to do it.

Unfortunately, I think I would need a higher speed video camera to get a better quality photo. When I first started setting up the video, the tape on the ball was white and ran from my PAP to over my fingers. But, I guess after a few test shots, that was enough for it to get mangled a bit.

Still, I am very happy with the results. I wanted to know my starting point in RPMs, MPH, Axis Rotation, and Tilt before attempting any changes in my form and release. Now I do, thanks!

thanks for that! I believe when I used the overlay my axis tilt is 10deg and axis of rotation is 75deg. this could be +- 1deg. based on the overlay and how i sized it, but, it's close.
is the only way to post a photo inline with my reply with a url?

rr

You can use File Manager under Post Options to upload a picture inline, without a URL.

ok thanks. i'll look at that. then below is the overlay on my ball using the pap and tape. see if i read it right.

tilt 75deg axis of rotation 10deg.

rr

Sorry, I can't really see the tape or PAP very well. But, if the PAP is the intersection of the vertical and lower diagonal line it appears to be 75 degrees axis rotation, and 5 degrees axis tilt.

I learned a lesson after my first effort, and the next time I used brightly colored removable dots instead of tape. See below. The orange dot is my PAP. The yellow dots are to help count the revs. The dots seemed to survive the ball return much better than the tape, and made it easier to recalculate my axis rotation (65 degrees) and axis tilt (15 degrees).