How To Pressurize / Revive Old Tennis Balls...

Discussion in 'Other Equipment' started by SeasonedNovice, Sep 19, 2011.

  1. Bagel

    Bagel New User

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    I got the Tennis Ball Charger 150 from Set US Tennis. I have been very happy with the result. The unit is equipped with a air valve on top so you can charge it with a compressor instead of the hand pump. It also comes with a special tool that allows you to tighten the cap so that it doesn't lose pressure over time. When I bought the device I had 144 Penn heavy duty balls about 2 weeks old which I use with a ball machine. I put the balls into the device and left them for 5 days and when I removed them they bounced just like new ones. There are only a couple of small negatives. The unit only holds about 140 balls, and you have to remove them manually rather than just dumping them out. It still only takes a couple of minutes. A little pricey at $300 but worth it in not having to fabricate something myself that may or may not work right. The benefit is saving money on balls and always having the correct bounce when I practice.
     
  2. Chotobaka

    Chotobaka Hall of Fame

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  3. ignacvucko

    ignacvucko New User

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    Schrader valve?

    Hey retrograde,

    Can you give me the size and/or partnumber for the schrader valve you are used? Also, what size tubing are you using for the valve? (I have tubing that's 5/16" x 9/16" OD)

    Thanks!
    Ignac
     
  4. retrograde

    retrograde Rookie

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    You'll want 1/4" ID tubing. Mine is 1/4" ID x 3/8" OD. The thicker the wall on the tubing, the trickier it will be to fit the tubing over the air valve and the tank's disconnects. Heating the tubing with something like a hair dryer will make the tubing pliable enough where you can slip it over the barbed end of the disconnect and the tank side of the air valve.

    Just go to your local auto parts store and ask for an air tank valve that has a 1/4" threaded end (got mine at O'Reilly). They cost around $2. Google "air tank valve" if you want to see pictures.
     
  5. CHOcobo

    CHOcobo Professional

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    I've been wanting to do this for a long time. Do you guys think one of those big glass pickle jar can handle 28psi of pressure daily?
     
  6. Ronaldo

    Ronaldo G.O.A.T.

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    Only when you leave the pickles in the jar
     
  7. MaconTennisClub

    MaconTennisClub New User

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    Just found this thread and thought I'd share what I've been working on... comments/suggestions welcome.

    I just started playing again recreationally after a 20 year hiatus and find that the felt on the balls far outlasts the balls going "dead". My local county tennis center has ball machines for rent, and includes practice balls to be used in the machines. However, all of the balls are totally dead which makes practicing with them tedious and impractical.

    My thoughts are to use a "paint pot" as mentioned here earlier in the thread. I bought one at HF for $80 ($100 less the 20% off coupon). I removed all the fittings (including the safety pressure release valve) and added a male inlet and a pressure gauge. The pot is steel, 2.5 gallons, and hold about 30 tennis balls.

    So far, I've observed that the balls start to crush (you can hear them deforming inside the pot) at about 40psi. The pot from HF is relatively cheap and so the seal doesn't work very well. An easy solution for this is to just set your regulator for the desired pressure from your air compressor, and let it run and maintain the pressure in the pot as it leaks.

    My plan is to chart out different pressures/durations to determine the most efficient pressure/duration for reviving a "dead" ball. For instance, I plan to take known dead balls (exposed to the atmosphere for at least 6 months), measure their rebound (using a rig I set up), then "pressurize" them at 15psi, 20psi, 30psi, etc. for 24 hours, 48 hours, 72 hours, etc. After each round in the pot, I'll retest their rebound to determine how much "bounce" is gained. It will probably take a few weeks to come up with the right blend of pressure/duration, but it seems like it'd be the most empirical way of doing this.

    The commercial product that goes for several thousand dollars (and perhaps can only be leased) doesn't give much information other than 50psi and 4-5 days. Since there's no easy way to test the internal pressure of the balls, my thought is that the simplest solution is to measure the rebound when dropped from a specific height. My rig drops balls straight down from 100" as specified by the USTA. I plan to use my hi-speed camera to capture rebound height.

    I'd love to know everyone's thoughts -- especially if you've attempted something like this already.

    thanks!
     
  8. IdrinkYourMilkshake

    IdrinkYourMilkshake Rookie

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    Sounds great. Just make sure to keep track of ball brands along the way. Two balls equally dead do bounce different heights if they are from different companies.
    My experience is anything 25,30,40 etc doesn't work as well as 18-20 over a couple weeks. It will be interesting to see what results you get. Keep us posted, thanks!
     
  9. MaconTennisClub

    MaconTennisClub New User

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    Here's a picture of the "setup".

    I've been thinking about testing the "rebound" of the balls, and have decided that rather than spend the time and energy reviewing film, I'll likely just use the "thud" sound on the first and second bounces and compute the height by taking the time interval between bounces. I think this approach will be more practical, consistent, and faster.

    Here's a picture of the "setup".
    [​IMG]
     
  10. v-verb

    v-verb Hall of Fame

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    I'm going to do this - I got a ball machine and it's hell hitting dead balls
     
  11. MaconTennisClub

    MaconTennisClub New User

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    Thanks for the info v-verb!

    It looks like the canner version is aimed at maintaining the pressure of new balls -- but could certainly work with re-pressurizing also.

    I'm most curious about the finding the "optimal" pressure/duration to recharge balls the fastest. I'm also curious about how much speed could come from "overcharging" balls beyond regulation pressures. Obviously, you couldn't use these balls in tournaments, but they could certainly be fun to play with if there's a significant difference.

    From my observations so far, I calculated a fresh set of Penn Championship balls as rebounding between 60-61 inches. This measurement does not factor in drag (as my rig isn't in a vacuum). My height might also not be EXACTLY 100" (although it's very very close if it isn't). Ultimately, it doesn't really matter though. My standard for comparison is my calculated rebound height of brand new balls. "Dead" balls rebound 50-53 inches per my calculations.

    Thanks again for the post -- let us know your progress!
     
  12. Nostradamus

    Nostradamus G.O.A.T.

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    this is nice, but if the ball loses all its fur, then it just flies thru the air too fast and is very hard to control still
     
  13. MaconTennisClub

    MaconTennisClub New User

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    True -- the re-pressurization process only makes sense under the assumption that the "fuzz" is still intact and that the ball is otherwise still playable. This comes into play more often with balls used for a ball machine rather than match play.

    Balls used in match play are struck by rackets and against the ground hundreds of times in the course of a few sets. Generally, people only use a few (3-6 balls) during a match. However, with a ball machine, you may have 100 balls and only strike each a few times depending on how many times you reload the machine.

    If you don't have the chance to make it to the court to practice with the ball machine very often, then you could go months without wearing down the fuzz on perhaps hundreds of otherwise "good" balls that go "dead" in a few days/weeks...

    Tennis facilities and country clubs also have hoppers and hoppers full of gently used balls (often played once during tournaments) that coaches/pros use for teaching/practice. These balls often end up "dead" way before the fuzz is gone... It's literally thousands and thousands of dollars that go to waste...
     
  14. atai

    atai New User

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    Looking forward to your results! By the way, one good way to precisely find the bounce height is to take a high-frame-rate video of the ball against a white background and measuring tape. Then, you can play back the video and freeze it as the height of the bounce. The MythBusters used this technique many times for measurements of fast moving objects.
     
  15. MaconTennisClub

    MaconTennisClub New User

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    Thanks! I actually tried that approach at first, but it involves a considerable amount of setup time and review. Camera angles, frame rate, shadows, zoom, lighting, human error, and a million other factors make that approach much less reliable than simply computing the theoretical height using the time differential between bounce 1 and bounce 2.

    In reality, for what I'm trying to accomplish, the actual numerical rebound height is irrelevant. What matters is having a fast, easy, consistent method of comparing the relative bounce differences between "new" and "flat" balls.
     
  16. Dags

    Dags Professional

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    If you have an iOS device, there's a free app called ballTester. The developer posts on this board as stoneage, and is best known for another app called racquetTune.
     
  17. SFrazeur

    SFrazeur Legend

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    Any updates from people?
     
  18. Ronaldo

    Ronaldo G.O.A.T.

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    NE has adopted a new policy using the above Ballicek app.
     
  19. SFrazeur

    SFrazeur Legend

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    I do not understand what you have said.
     
  20. Ronaldo

    Ronaldo G.O.A.T.

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    The Belichick app to check ball pressure. Btw, new problem with used balls. Carts are filled with used balls then pushed behind curtains where it is cold. Rarely find a ball that bounces.
     
    Last edited: Feb 4, 2015
  21. SFrazeur

    SFrazeur Legend

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    Cold is a ball killer.
     
  22. gambitt

    gambitt Professional

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    I bought a Corny keg a few months ago and filled it with 50 balls. Not getting the results that everyone else is getting.

    First tried at 25 psi for 2 weeks - 3 balls had recharged out of 50
    Put 47 back in at 30 psi for 4 weeks - 2 balls had recharged, the rest were still flat

    I've noticed Head Radical balls and Wilson Extra Duty are the only ones that have recharged so far. I have a lot of Dunlop Fort All Court in there and they don't seem to want to recharge at all.

    What's the deal? Does it only work on balls that are slightly flat? I admit that some of the balls I am using have been in the back of my closet for a year (extra squishy).
     
  23. wolfinsignia

    wolfinsignia New User

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    dunlop balls usually last me a long time. its probably the rubber prevents air flow at a better rate.

    also i don't know about the steel vessel, but with almost all other not mechanize ball pressurizer you will need to adjust the psi every couple of days.

    anyways i plan on getting a 2 gallon pump spray sometime this month. attach a psi gauge and see how that does. should hold about 10-20 balls .
     
  24. gambitt

    gambitt Professional

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    I check the pressure every few days and it's only ever dropped by a fraction (like 29.5 psi instead of 30). I might just crank it up to 50 and see what happens after 2 weeks.
     
  25. Nostradamus

    Nostradamus G.O.A.T.

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    Can they EVER invent a tennis ball that Never loses its pressure ever ? is this even possible ? I am not talking about the pressureless balls, those are too heavy and too harsh on the arms.
     
  26. Nostradamus

    Nostradamus G.O.A.T.

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    and Dead balls are really bad for your shoulder and back as well. it Causes injuries.......
     
  27. SFrazeur

    SFrazeur Legend

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    My understanding is for the best results you really need to use CO2 and not just air.
     
  28. gambitt

    gambitt Professional

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    jumping out of a moving car is also bad for your shoulder and back, but no one in this thread is suggesting doing that either.
     
    Last edited: Feb 13, 2015
  29. gambitt

    gambitt Professional

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    I'm finally seeing some results with my corny keg. I'm unsure if this is scientifically accurate but I microwaved some of the balls first and then quickly threw them in the keg and ramped the pressure to 40 psi. This seemed to help with the repressurizing when I took them out a couple of weeks later, but it could have been a fluke. I'll try it with some of the "stubborn" balls next week.
     
  30. sundaypunch

    sundaypunch Hall of Fame

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    If you are looking to revive old balls that is probably the best. If you have a ball machine, keeping them pressurized at 15psi will make them last almost indefinitely. The balls eventually start losing their fuzz and bounce too much.
     
  31. parasailing

    parasailing Hall of Fame

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    Only problem I see with pressurizing balls is that you would have to do it with balls that still have a good amount of felt on them. Having ones that don't have much felt would be like playing with pressure less ones which offer bounce but don't play like regular tennis balls because they don't have a good amount of felt on them.
     
  32. volusiano

    volusiano Hall of Fame

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    I think you hit the nail on the head there about it only working with balls being slightly flat.

    The problem is that very flat balls under higher pressure on the outside tend to get squished in and lose their round shape easily if the outside pressure is too much for the inside pressure plus the rubber to hold up its round shape. Once the very flat ball caves in with a dent, it cannot get repressurized properly due to its odd shape now.

    I have the clear Pressureball tube with 8 balls inside stored at 20 psi and I've seen first hand how easy it is for several very flat balls to cave in under 20 psi, thanks to the transparency of the clear tube. When you release the pressure those flat caved in balls pop back out to the round shape. So you wouldn't know if you can't see the balls inside your container when stored.
     
    Last edited: Mar 24, 2015
  33. barderer

    barderer New User

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    Guys and Gals,

    We need to revive this thread. The problem with all the suggested solutions are they are extremely expensive, hard to load balls in and out etc. I am thinking about buying a 5 gal metal bucket with a level and rubber seal and just pumping until it explodes to see what the max pressure it can take. If the thing can hold 20 PSI its "good enough". I have a feeling it will fail with a leak before it actually explodes. You could add a clamping system to the top and bottom to make the lid better handle the pressure. Has anyone tried pumping one of these up until it fails?

    http://www.yankeecontainers.com/c/do-your-buckets-pails-come-with-lids/img_4693/

    Of course safety etc. will be considered blah blah blah.

    Nick
     
  34. volusiano

    volusiano Hall of Fame

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    Why do you need to pump a metal bucket up until it explodes or until it fails? What's the point of doing that? It's already been said that even at only 20 psi, flat balls can easily implode and can't hold their round shape anymore. And once this happens, there's no way to recharge them. So you can only charge slightly flat balls without imploding them at a lower pressure like 20 lbs. At a higher pressure, at some point even only slightly flat balls will also implode. And if you don't have a transparent container, you won't see whether the balls will implode or not. Even if a transparent container, if it's a big container, you can only observe the outer balls and you won't see the inside balls and be able to tell whether they implode or not.

    So in my opinion, the best option is to only go up to 20psi and recharge only slightly flat balls and not completely flat balls.

    Rebounces dot com accept completely flat balls, however. So maybe they have a way to workaround the problem of ball implosion. The only obvious way I see is to sort them (by hand?) to different degrees of flat balls, and use the appropriate pressure to recharge each group separately until eventually at some point they will get fully recharged. This manual sorting can be pretty labor intensive, though.
     
    Last edited: Jul 23, 2015
  35. barderer

    barderer New User

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    The purpose is to find out how much the bucket can take so when you do 20 psi over and over again you know it won't fail / blow up on you. If it can be taken to 50 PSI and above and still hold you can fell REALLY good about keeping it at 20 psi month after month. Safety.
     
  36. volusiano

    volusiano Hall of Fame

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    You may not know this, but the clear Pressureball tube I was referring to earlier is merely a flexible soft PLASTIC tube held together by either glue or heat seams around the edges. and as you pressurize the tube, it actually starts expanding when filled with air. At around 15 to 20 psi it stops expanding and becomes firm. But if you continue to pressurize it further, it can expand even more. But it's not recommended to be pressurized at over 20 lbs.

    So if a soft plastic tube like the Pressureball can hold pressure just fine at 20 psi, I'm sure a hard metal or plastic bucket won't blow up on your face at 20 psi.

    Now whether it'll leak eventually or not is a different story. But then leaking is not a safety issue. It's a reliability issue.

    I had the Pressureball tubes (3 of them) for 6 months before all 3 started leaking. I contact Barry Mulder (of Pressureball) and he asked me to pour some boiling water over the seal at the opening to tighten up the seal. It didn't really help so he sent me 3 replacement tubes (and an extra to cover my return shipping cost of the 3 defective tubes back to him to investigate). Time will tell if the new replacement tubes will hold up any longer or not. These tubes have a 1 year warranty but he said they should last easily for a couple of years. Apparently my first 3 lasted only 6 months. But at least he's honoring his warranty and was very nice and easy to work with.
     
  37. barderer

    barderer New User

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    Cool product! However I am looking to build something that can hold 50-100 balls, is cheap, and is really for ball machine use. That is the problem with the ball machine, flat balls. Hence the metal bucket. Guess I will just order one and test it.
     
  38. ibo

    ibo New User

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    So people, what's the conclusion after all this experimentation ? I have been thinking about the paint pot approach and perhaps also trying a cheaper solution like the zombie tube or something similar. Can anyone put forward something that is known to work consistently ?
     
  39. volusiano

    volusiano Hall of Fame

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    The conclusion is that repressurizing flat balls work as long as you're careful to match the ball flatness with the pressure level used. Too high a pressure on too flat a ball will cause the ball to become squished and it can't be recharged under that condition. This means you don't need to concoct a setup that can hold very high pressure. Around 20 psi is good enough for slightly flat balls. And that means even less (15 psi or less) for flatter balls.

    The conclusion on what setup works is pretty much any setup you can buy or build that will hold up to about 20 psi and not leak.
     
  40. ibo

    ibo New User

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    Thanks. Got it. Has anyone here tried the Zombie tube ? I feel like that's the one I want to try first.
     

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