Corny Keg or Tretorn/Triniti Balls

brady1212

New User
I am debating between 3 options for ball machine balls this year.

1) Traditional balls which will pressurized via Corny Kegs when not in use
2) Tretorn Micro x
3) Wilson Triniti

I am curious from people that have tried any of the above methods and your thoughts on how they worked out. Thanks for your time.
 

zinzan8

Rookie
I'm experimenting with #1 right now. Old balls are still one week under pressure, so too early to say much. But I can say that gathering the parts, putting it all together and holding pressure (understanding where leaks can occur and how to handle them) can be a bit fiddly. But I expect that it will work out well and be pretty easy to maintain a rotation of balls after two or three cycles.

I don't have good experiences with pressureless balls. Very hard on my elbow. Still have a sack of 45 of them in my garage. Put them in my ball machine and removed them after a couple dozen hits. But those were Penn. Have not tried Tretorn Micro X.

I did pick up a couple "cans" of Wilson Triniti. They play fine for me, and don't feel weird coming out of a ball machine. Much better than pressureless IME. But not sure about longevity yet... supposedly 3 times longer than pressurized balls? Honestly, if you like how they play and can get 3 times the life, picking up a case of these might be a reasonable solution.
 
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D

Deleted member 768841

Guest
The triniti definitely keeps its pop, I have had a “can” for around 4-5 months and it still has a good amount of pressure left.
 

JEDI MASTER

Semi-Pro
trinity balls start out hard and heavy hitting it... but after 3 days of 2-3 sets.. they start to feel better on the arm.
good bounce and felt is holding up much better. for my Ball machine.. i'd just buy a case or 2 of Penn balls from Costco.
 

mad dog1

G.O.A.T.
Tretorn micro x

corny keg is too much trouble. You’ll spend too much time trying to fill and dump the balls out of the keg. It’ll get old really fast.

i had the SET tennis ball pressurizer and pumped it up with a compressor. the opening was larger than the opening on the corny keg so balls were easier to get in and out. Still got sick of it pretty quickly.
 
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Ronaldo

Bionic Poster
Tretorn micro x

corny keg is too much trouble. You’ll spend too much time trying to fill and dump the balls out of the keg. It’ll get old really fast.
Had three of them. Balls are hard to empty but keep their bounce. Had access to hundreds of fresh balls at club, stopped using the kegs.
 

r2473

Talk Tennis Guru
Tretorn

All the retailers are on back order for these. Which means a new run from the factory. If you can, wait until people buy them and post reviews. They’ve done bad runs in the past.
 

brady1212

New User
I guess I underestimated the inconvience factor of the using the keg. Thanks for the feedback everyone. I guess I will grab some Tretorn balls
 

zinzan8

Rookie
Inconvenience seems worth it to me, at least for now, and after $50-55 invested in corny keg and attachments.

Maybe I'll be tired of it after a year, but I'm going to save $55 on tennis balls first, dammit! :)

But sure, if I had access to hundreds of fresh balls (assuming no coronavirus fears), or could easily afford buying fresh balls by the case often, I wouldn't bother with the corny keg.

Or if pressureless balls didn't kill my elbow. I should try the tretorns sometime, I guess.
 

Ronaldo

Bionic Poster
Inconvenience seems worth it to me, at least for now, and after $50-55 invested in corny keg and attachments.

Maybe I'll be tired of it after a year, but I'm going to save $55 on tennis balls first, dammit! :)

But sure, if I had access to hundreds of fresh balls (assuming no coronavirus fears), or could easily afford buying fresh balls by the case often, I wouldn't bother with the corny keg.

Or if pressureless balls didn't kill my elbow. I should try the tretorns sometime, I guess.
Discovered when I had it all, could not handle it. Found corny kegs on the bay all set up for $29 each.
 

Nogo

New User
Corny keg I'd say takes about 1-2 minutes max to empty and 2-3 minutes max to fill up and pressurize manually with a bike pump, no rushing. This is assuming the keg is full of balls, which you need to help get out with your hand. I don't mind it.
 
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Ronaldo

Bionic Poster
Corny keg I'd say takes about 1-2 minutes max to empty and 2-3 minutes max to fill up and pressurize manually with a bike pump, no rushing. This is assuming the keg is full of balls, which you need to help get out with your hand. I don't mind it.
Only got wonky when whipping out your practice balls. Gotta love the look on the next court when de-pressurizing the chamber.
 

brady1212

New User
For the people with the kegs what does your ball rotation look like? By that I mean how many kegs/balls are you using and how often are you rotating them in and out?
 

zinzan8

Rookie
For the people with the kegs what does your ball rotation look like? By that I mean how many kegs/balls are you using and how often are you rotating them in and out?
k

Good question.

Currently, I have about 60 old balls (mostly Penn, some random pickups) and about 60 almost new Dunlop ATPs.

I just repressurized the old balls (2 weeks+) and will use them with my ball machine for a week while I keg the Dunlops. Then I'll swap every weekend so no balls are more than a week out of the keg. We'll see how that works.

I may end up combining them when I want to really fill the machine, and could keep one set or the other in the keg when I'm not playing, alternating (I've marked the old set with one black dot from a Sharpie on the seam below the logo and the new Dunlops with two red dots) every week or so. That might be too much of a hassle, but it's an option.

Or I might end up buying another keg. Maybe should have bought two up front, and saved $9 on shipping, but wanted to prove to myself that repressurizing is really worthwhile.

There is a YT video out there where a guy has two kegs (or was it 3?) and rotates balls in play with balls getting kegged.
 

Ronaldo

Bionic Poster
k

Good question.

Currently, I have about 60 old balls (mostly Penn, some random pickups) and about 60 almost new Dunlop ATPs.

I just repressurized the old balls (2 weeks+) and will use them with my ball machine for a week while I keg the Dunlops. Then I'll swap every weekend so no balls are more than a week out of the keg. We'll see how that works.

I may end up combining them when I want to really fill the machine, and could keep one set or the other in the keg when I'm not playing, alternating (I've marked the old set with one black dot from a Sharpie on the seam below the logo and the new Dunlops with two red dots) every week or so. That might be too much of a hassle, but it's an option.

Or I might end up buying another keg. Maybe should have bought two up front, and saved $9 on shipping, but wanted to prove to myself that repressurizing is really worthwhile.

There is a YT video out there where a guy has two kegs (or was it 3?) and rotates balls in play with balls getting kegged.
Had three kegs (~90 balls) for a ball machine but rarely used the machine during the summer. Thirty balls for practice was not neccessary, had access to old balls discarded after USTA League matches, at least a dozen everyday. A plethora of lively balls. So many that I would leave them on the HS courts.
 

stapletonj

Hall of Fame
Hey all, I am a Guinea pig for a guy in Cincy. put about 40/50 balls in a corney keg he made and is selling. used a bicycle pump up to 32 psi, with just air.
a variety of balls, mostly Wilson US Opens, but some dunlops and/or extra duty felt penns. waited 2 weeks. Some were pretty dead, some decently bouncy, but not new (figure about 2/3 hours of hitting). kept it in my decently warm (60-70 degrees) exercise room.

pressure (according to the gauge, which I presume is accurate) held just fine (went up slowly as I pumped it up with the bicycle pump).

pulled them out after 2 weeks, no noticeable diff. in ANY of them. I'm gonna go up to 50 lbs and see what that does.

Anybody have any speculation as to what went wrong?
 

Injured Again

Hall of Fame
Hey all, I am a Guinea pig for a guy in Cincy. put about 40/50 balls in a corney keg he made and is selling. used a bicycle pump up to 32 psi, with just air.
a variety of balls, mostly Wilson US Opens, but some dunlops and/or extra duty felt penns. waited 2 weeks. Some were pretty dead, some decently bouncy, but not new (figure about 2/3 hours of hitting). kept it in my decently warm (60-70 degrees) exercise room.

pressure (according to the gauge, which I presume is accurate) held just fine (went up slowly as I pumped it up with the bicycle pump).

pulled them out after 2 weeks, no noticeable diff. in ANY of them. I'm gonna go up to 50 lbs and see what that does.

Anybody have any speculation as to what went wrong?
Long winded and rambling post coming...

I've had my corny keg for about a month and have been playing around with it. Because indoor tennis is not available and our weather is pretty terrible, I haven't been playing a whole lot so the balls sit in the corny keg for days at a time.

My primary use for the corny keg is to occasionally repressurize some used balls for practice. I find that even if I can restore the bounce height, used balls don't bounce forward as far, and require high racquet head speeds to generate the same ball speed off the strings. It's a great way to simulate playing on slower courts since those in our facility are medium speed or faster.

Anyhow, since I only have at most a dozen balls to repressurize at any one time, I've been trying to find a way to reduce the internal volume so I don't have to do 120+ pump strokes to get to 30-35 PSI and I've done that by by using old tennis balls. I've found that a week in the corny keg at 30 PSI restores once-used balls to as-new or higher bounce. Some pretty dead balls that I've had in there for most of the month just to take up space, now are more bouncy than new balls. I haven't hit with them yet since there's little fuzz left but I'll bring a couple out to try next time. Some balls respond better - US Open balls seems to restore to new bounce condition within a few days. Dunlop Championship balls take a week or a bit more to reach the same point. That's surprising because the US Open balls also retain pressure better so I would have expected it to take longer to repressurize them.

As to what you've experienced, I can only think that maybe your balls were so depressurized that they collapsed when you pressurized the container. But it seems strange that none of the balls got better. For me, none of the balls **didn't** get better. My corny keg is sitting in the garage that is about 50 degrees F. so permeability should be less than your warm exercise room. I think 50 PSI will definitely collapse the balls and prevent them from repressurizing.

My only other guess would be if the balls were all pretty damp or got covered with some sort of oily substance that could have reduced permeability? But that seems pretty unlikely.
 

Ronaldo

Bionic Poster
Long winded and rambling post coming...

I've had my corny keg for about a month and have been playing around with it. Because indoor tennis is not available and our weather is pretty terrible, I haven't been playing a whole lot so the balls sit in the corny keg for days at a time.

My primary use for the corny keg is to occasionally repressurize some used balls for practice. I find that even if I can restore the bounce height, used balls don't bounce forward as far, and require high racquet head speeds to generate the same ball speed off the strings. It's a great way to simulate playing on slower courts since those in our facility are medium speed or faster.

Anyhow, since I only have at most a dozen balls to repressurize at any one time, I've been trying to find a way to reduce the internal volume so I don't have to do 120+ pump strokes to get to 30-35 PSI and I've done that by by using old tennis balls. I've found that a week in the corny keg at 30 PSI restores once-used balls to as-new or higher bounce. Some pretty dead balls that I've had in there for most of the month just to take up space, now are more bouncy than new balls. I haven't hit with them yet since there's little fuzz left but I'll bring a couple out to try next time. Some balls respond better - US Open balls seems to restore to new bounce condition within a few days. Dunlop Championship balls take a week or a bit more to reach the same point. That's surprising because the US Open balls also retain pressure better so I would have expected it to take longer to repressurize them.

As to what you've experienced, I can only think that maybe your balls were so depressurized that they collapsed when you pressurized the container. But it seems strange that none of the balls got better. For me, none of the balls **didn't** get better. My corny keg is sitting in the garage that is about 50 degrees F. so permeability should be less than your warm exercise room. I think 50 PSI will definitely collapse the balls and prevent them from repressurizing.

My only other guess would be if the balls were all pretty damp or got covered with some sort of oily substance that could have reduced permeability? But that seems pretty unlikely.
Had three korny kegs and had the same results. Nearly new bounce
 

stapletonj

Hall of Fame
I'm going to try again, this time with 40-45 lbs pressure, if some of them collapse, so be it.
none of them collapsed at 32 psi......
 

Demented

Semi-Pro
I'd say that trying to pressurize them too high is a mistake. The idea is that you don't want the ball to decrease in volume not just collapse. If you overpressure the outside too much and the ball shrinks but doesn't collapse then you'll fail to force air into the interior because the volume has decreased inside which raises the air pressure. As soon as the external air pressure is reduced, the ball expands again and the pressure lowers. I think you need to sit them at like 19 psi and let them sit for a long time(2 weeks) and slowly absorb external air.

I'm using the Korny keg system but I have a distinct advantage. The twice weekly morning women's league leaves me 20-40 new balls, barely scuffed with no obvious signs of wear to gather and stuff into my kegs. Then I retrieve them from storage whenever I go play.
 

Nollid

Semi-Pro
Slightly off topic. Not the same capacity as a keg but each of these tubes hold eight balls. I have three of them. Easy to use and they work. Maybe not so much for ball machine balls, but they save me from having to open a new can every session.
 

Injured Again

Hall of Fame
Slightly off topic. Not the same capacity as a keg but each of these tubes hold eight balls. I have three of them. Easy to use and they work. Maybe not so much for ball machine balls, but they save me from having to open a new can every session.
I had a PressureTube that I used for just over one year before it sprung a couple of leaks. Very easy and nice for maintaining bounce but it couldn't be pressurized enough to restore bounce. I think the upper limit was around 20-25 PSI so any repressurization of used balls would take a few weeks or longer. It's a better solution for the majority of players who want to just be able to use the balls a couple of sessions before discarding them. By the way, I was able to easily get nine balls in the one I had. That didn't cause the leaks, which were in the bottom seal and in the material surrounding the valve.
 
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