This is great to know! I may have to do this because I play a lot of tennis and it would really save me some dough in the long run. Been playing 8 years now. Thank you!
Good video detailing process. I don't play tennis.I often find tennis balls when walking. As an experiment, I used a trailer tire to restore the pressure.
Since I have a tank with a clear "window" and can observe what is going on inside the tank. I just wanted to let you know that at around 35-40 psi most of the balls will collapse. One side of the ball will just cave in as if you have sucked the air out of the ball. If you start hearing the "popping" sounds coming from inside the tank - that's exactly what is going on. I don't think that this can pressurize the balls any better or faster. I would even think that if you were to leave them in that state for a long time, the rubber will get permanently deformed and the balls might even crack at the seems. You really shouldn't go over 30 psi - just leaving the balls in the tank for a longer period will do the trick.
I’ve been pressurizing balls for several years with this setup and no problems. Yes, I hear the popcorn sound too, but the CO2 gets in the balls and they come out re pressurized. I use 50 psi for 3 days.
You sir are a genius. I really don't like to hit sphere-shaped stones (a.k.a. pressureless balls) on my ball machine and even if I were filthy rich and could somehow afford to buy 120 pressurized tennis balls every 2 weeks, there is no way I would be okay with polluting the environment to that degree. Thank you so much for this. I am sold! I won't do the 32 psi thing with dead balls, but I will definitely do the 14 psi with barely used balls. Perhaps 15 psi max. I truly appreciate what you've done here!
Interesting experiment. I would be curious to see how they held up on the tennis court, do they last a whole hitting session, or maybe only 2-3 hits? Also, you can re-pressurize them, but you won't be able to put the felt covering back on.
Great video and idea in general. Had me thinking that for people like me who would not have access to such a keg type canister, perhaps a pressure cooker can be used with similar effect. I might give this a shot given my wife spares a cooker for my experiment :) Thanks for the good work.
thanks so much for the videos. how has it gone after a year? (a one year update video?) are you still using this system? any sense of how long you can keep doing this (how many cycles? do the balls last a long time until they start getting bald?) And seems the 14 psi for new balls would be a good way to keep newish ball, mostly new without having to do the overpressurizing period. but great idea for old balls. i saw you recorded on iPhone X. did you edit on the phone or use a computer?
Awesome video man! Quick question though…when pressurizing the chamber, I noticed that I’m hearing and feeling “popping” inside (at around 30 PSI). Are the tennis balls bursting? 😲 The balls are about a year old.
Just so you guys know: A ball is tested for bounce by dropping it from a height of 254 cm (100 inches) onto concrete and should bounce back between 135 and 147 cm (53 and 58 inches)
Quick question for you. After you re-pressurized 32 psi the tennis balls, then how do you store them? Put them back in keg with 14 psi like the new can of tennis balls to keep them fresh? Thanks Jeff
Just a physics question: lets say the air pressure is around 15 psi and the regular pressure inside a tennis ball is 26, you would only need to add 11 more psi to bring it to equilibrium. give or take. I noticed that my pressure gauge starts at 0 PSI, which would be vacuum, not 15, aka air pressure, which means whatever the gauge is showing is additional psi to air pressure. In this case, we only need 11 PSI more? I understand the higher the pressure outside, the faster it will pressurelize the ball. Just wanted to check the physcis here.
Hi Eddie, thanks a lot for doing this video! Do the old repressurised balls maintain their pressure similar to newly opened balls - or do they lose their pressure more quickly?
I have re-pressurized more than 200 balls using this Corny Keg. The re-pressurized balls maintain their pressure just like new balls. I do not observe any difference at all.
Finally something scientific, thanks mate! Could you kindly clarify why after the experiment you suggest keeping the balls inside the canister at 14psi which is lower than the atmospheric pressure of 15psi?
The 14 psi that he refers to is 14psig (gauge pressure), this is in addition to the already 14.7 psi of the atmosphere. Thus the balls are experiencing 28.7 psia (atmospheric pressure), or about 2 atm. My guess is that this increases the lifespan because there's less pressure difference between the inside and outside of the ball. Perhaps Penn tennis ball pressure is around 14psig and the 30 psig is over-pressuring to revive a dead ball.
I use conelius keg like you do but pressurize with CO2 from a tank designed for pressurizing beer. This is what commercially available ReBounce machines do. Apparently CO 2 molecules are slightly smaller than air molecules so they enter balls easier and quicker. I pressurize to 50 psi and leave balls in for 3 days, come out great! Amount of balls vs air is not an issue. I fill my corny kegs with 60 something balls per use.
@@TennisOnAction check if you connected it to the IN section, and then check if all the seals are ok. Sometimes the release pressure valve is worn out, or some orings.
No, the balls do not collapse. I don’t have a window in my keg, but I hear the popcorn effect. It did the same when I demoed the ReBounce unit. The balls come out great. In my experience Wilson US Open balls take re pressurizing best, and you can recharge them twice if they still have enough felt. I’ve even gone three times. The other commenter doesn’t seem like he has much experience, I’ve been doing this for more than 5 years. BTW go with CO2, it’s so much faster and convenient.
@@georgeschuldberg1382 can you share a little more about how you are pumping CO2 into the tank? I’ve got 3 of the corney kegs, but I haven’t had good results trying to repressurize them at 32psi for 2-3 weeks. I don’t know if it’s because I’m using balls that are too-dead, or something else. Would love to hear more of your experience, especially if you tried repressurizing with regular air.
nope , there is no manometer on the tank , who says there is no small leak, or the surrounding temp changed the pressure the bounce surface is uneven should be a flat hard surface like concrete or a steel plate . are the new balls the same temperature than the pressurized balls ? etc i dont say its a bad test , but scientific nope
Hello brother. Would you tell me how many times did they supported re-pressurization process? How did they feel on the court and how many games did they last after that
@@cornutopia1389 though the balls will collapse at high pressures, the 2nd law of thermal dynamics kick in and will push the high surrounding pressure into the balls until they are equal. I experimented with a high pressure canister at 120 PSI over several months. Results were balls that bounced slightly higher than new balls from a can
Why does it lose air in the first place? Can't they add a thin layer of sealant or something on the inside to stop air from escaping..ever? Car tyres don't lose pressure except for puncture so why can't the same be applied to tennis balls? I just play tennis socially but I am burning through balls and it's getting pricey.
What is the recommended pressure for keeping/refreshing the (nearly) new balls, i.e. after couple weeks of play? 30-32 is good for repressurizing old balls, but probably too much for the new balls?
Recently I've come to this idea but still hesitating as I'm low level amateur training once or twice a week. How would you estimate the difference between playing new balls and 70% worn out ones but pressurized to 14psi? Thank you so much for this research.
This is a great question. I am also wondering if the re-pressurized balls will hold the bounce when you start practicing with them. I have played with a ball that looks to be bouncing well but after hitting with them for some time the stop bouncing that well.
@@MrNDQuattro I do not think it is related to the rubber. I am able to squees the ball with bare hand and it felt good and with a good amount of felt. I am able to bound it pretty similar to brand new balls. Then when you start practicing they stop bouncing and the felt is the same.
Hi Eddie, is there a reason you left them to get repressurized for 2 weeks? Would waiting only 1 week make a difference? Potentially at a higher pressure? I'm just trying to find the most efficient time and pressure levels as quick as possible. Great video and explaination! I'm building my own version adapting what you did to a ball and socket version of the keg and swapped out the tire inflation valve to directly put the valve on the air compressor hose. First keg is pressurized and waiting to see the results now.
if those contract is because they are "dead" ball struture might have gaps that don't allow to keep the pessure. I keep mine from new on a acrylic tube at 30-35 PSI and they bounce great, after a year, around 90 to 95% compared to a new tennis padel ball ( I play Padel). Try to keep them since day one, and rotate them. Mine are kept 1 week under pressure before playing with them. I have two tubes, and now i'm considering on a solution like this in order to keep them longer. Before i used to buy a can of balls every two / three weeks, now, i only buy them when a ball shrinks under pressure. Using Wilson balls they last close to a year, general brand balls (low cost) 4 months at its best.
Well done! You've sold me on giving it a shot. I use a Spinshot Player ball machine. Vendor recommends using pressureless balls, but pressureless are heavier (potential arm strain) and then you have to readjust anyway when playing with pressurized balls. Really? * scratches head *
you should have done what mythbusters did and create a device to drop the balls. that way it would be more precise rather than ripping them with your hand.
The pressurization can be improved. Too many balls in the container, too small volume of compressed air. the ideal situation is to have only 1 ball in the container, and a large volume of compressed air. but a compromise can be made....fill the tank with 25% volume as balls. 75% volume with compressed air.
I tried setting 30 psi and the balls completely collapse under the pressure. Do you know if that's OK and the balls will recover their shape after some time?
But it's still bad practice; in order to solve this probleb; one needs to solve both problems. Their is the bounce problem and the fuzzy problem; where these both create an environment towards a thing that I like to call"bad practice". You are better off not playing tennis if you aren't going to use the ball that will be used at the places where you will be playing against people that are your caliber and played with the same balls that you will be using for the match against you. There could be a way to keep yourself at logical of ratio if you were to use the new balls at intervals where you do practice with these in this video as to keep your witts about the habits that a new ball's reaction are upon spinning and the sound that it makes also should give you a heads up on what speed to expect it's coming. I've only had a segment of playing until we were starting to rally pretty good when I was 19 or so and without the fuzz; I don't know; I seem to kinda remember there being a difference but it also meant that the others were dead too. But ideal for the pressure would be an automatic thing and I could create that or tell you how if you'd like. I don't have the time to create anything that I figure out otherwise that would be all that I'd be doing and that isn't what I want to do. Cheers and give it a couple of days and I'll think of a few good ways. This was why I found this; because I checked if someone else thought of this but me I would had put a super tiny valve that would had let the air in quicker.
Ok so what I came up with is a choice between two ideas for now and one is to use that same liquid as the flat tire one use repair can but a more liquid if possible; or maybe FLEX dilluted with rubbing alcohol when I tried it to see if it would work but if you were to find the solvent for flex caulking and have it so it's almost like water; then injecting the correct amount would be Ideal; then you just play with it and it will fill all the pores and cure.I'm not sure but you may need to use a tiniest needle; if there are different siringe sizes. The second ideal wasn't as good or as easy and this next part was me writing it before and decided to give you these ideas prior to the reply because even though I wrote it before; it's something that would go better after; LOLOL whom cares right; of course. Cheers. You know what; one of these companies needs to make one that is airtight and that would solve your dead balls problems and for the fuzz there are things that could mimick; but cosmedically wouldn't be perfect but you could re-felt them I guess.
You could sell them in a container that is a three layer; where the outer layer's inner surface has threads that match with the outer surface of the middle layer and it's inner surface has seals that interact withe third layer's outer surface and then the balls return to the can (container)and now you screw the two parts together and the smaller the inside gets; the higher the air pressure it also becomes. There; that will be the last one. I am done like dinner. Cheers
Hi Eddie, Thanks for the videos! Did you hear balls collapsing while pressurizing? Here's a vid with the sound: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-cxEksyYMvlw.html I was wondering if you heard this sound (balls collapsing) while pressurizing, maybe the collapsed balls are simply equalizing and popping back to shape within the two weeks (?).
This video is really helpful; I understand what is going on. A possible solution is to raise the pressure slowly so when you add pressure to the inside of the can / outside of the ball, the pressure inside the ball has time to equalize without collapsing the ball... Maybe if you did 3-5 PSI per day or something like that?
It doesn’t work, I got the same setup after watching this video. Dead balls don’t re-pressurize. It only works to maintain pressure at whatever level the balls are.
@@CN-yc3eb That doesn't prove it can re-pressurize dead balls. It only maintains the level of remaining air in the ball. That's why balls come in a pressurized can. It only maintain the pressure. The pressure will never go up, but can always come down.
same thought. on wood, no doubt. sorry to knock. i've only come to this video because as a home brewer (former, sadly), i have tons of corny kegs and can do this for my tennis balls. I'm sold - at least you kept your methods the same from test to test even if you didn't bother bouncing them on the garage floor in the first video.
