travlerajm
Talk Tennis Guru
I recently bought a 3-ball Tennis Ball Saver.
These ball savers work well to quickly restore a used ball to about 90% of its original bounce height (this is my guesstimate, not measured yet). The once-used recharged balls bounce higher than once-used balls stored without the device, but supposedly takes a month or more to recharge used balls all the way back to 100% original bounce.
The Tennis Ball Saver stores the balls under approximately 14psi, which is the same pressure inside a can of new tennis balls. It works by compressing the air inside the can to about 1/2 of its volume, which doubles the pressure. The problem is that 14psi is not quite enough to ‘fully’ revive used balls - a bit more pressure is needed for that.
My idea is to see what happens if I fill up some of the air space between the balls with incompressible material. This way, when I close the device, it will compress the air volume to 30-40% of its uncompressed volume, rather than 50%. I have not done the math yet, but I figure this might give me something closer to 20psi rather than 14psi.
I expect the 20psi pressure will double or triple the recharge rate, and hopefully give me a fully revived 100% bounce height within 24h. I don’t want to use too much pressure, because that might give me an overcharged super ball that bounces 110% as high as freshly opened ball.
Today I bought 2 bungee cords for $1 each at Home Depot. One is 3/4” x 1/4” rectangular cross section, and the other is about 3/8” round. I cut these into 7” lengths so that I can bend them into rings to fill up some of the annular shaped space between the balls. I used a 3/8” ring at the bottom, the larger rectangular cord in the two annuli between balls, and another 3/8” ring at the top.
For now, I left it to charge my thrice-used Penns, which are beat up enough to have patches bare of felt, but still have 90% pressure due to being stored in the saver between uses. I can tell that the pressure is substantially higher than before because the end of the device is bulged convex a little.
Next time out, I will crack a fresh can and start them off afterward in my augmented saver, and bring a yardstick to compare bounce height ratio of new vs recharged.
The experiment begins.
These ball savers work well to quickly restore a used ball to about 90% of its original bounce height (this is my guesstimate, not measured yet). The once-used recharged balls bounce higher than once-used balls stored without the device, but supposedly takes a month or more to recharge used balls all the way back to 100% original bounce.
The Tennis Ball Saver stores the balls under approximately 14psi, which is the same pressure inside a can of new tennis balls. It works by compressing the air inside the can to about 1/2 of its volume, which doubles the pressure. The problem is that 14psi is not quite enough to ‘fully’ revive used balls - a bit more pressure is needed for that.
My idea is to see what happens if I fill up some of the air space between the balls with incompressible material. This way, when I close the device, it will compress the air volume to 30-40% of its uncompressed volume, rather than 50%. I have not done the math yet, but I figure this might give me something closer to 20psi rather than 14psi.
I expect the 20psi pressure will double or triple the recharge rate, and hopefully give me a fully revived 100% bounce height within 24h. I don’t want to use too much pressure, because that might give me an overcharged super ball that bounces 110% as high as freshly opened ball.
Today I bought 2 bungee cords for $1 each at Home Depot. One is 3/4” x 1/4” rectangular cross section, and the other is about 3/8” round. I cut these into 7” lengths so that I can bend them into rings to fill up some of the annular shaped space between the balls. I used a 3/8” ring at the bottom, the larger rectangular cord in the two annuli between balls, and another 3/8” ring at the top.
For now, I left it to charge my thrice-used Penns, which are beat up enough to have patches bare of felt, but still have 90% pressure due to being stored in the saver between uses. I can tell that the pressure is substantially higher than before because the end of the device is bulged convex a little.
Next time out, I will crack a fresh can and start them off afterward in my augmented saver, and bring a yardstick to compare bounce height ratio of new vs recharged.
The experiment begins.
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