RacquetTune app

[AJB]

After stringing my first two racquets using my new Klippermate, I checked the tension using RacquetTune. Within the hour - no play. To my surprise, the readout showed a tension between 2-4 lbs. higher than where I'd set the dropweight. (Yes, I had the Klip properly set up and had all the right specs put into RacquetTune for head size, string pattern and so on.) Can anyone shed some light on why this might be? I was meticulous about setting the dropweight correctly and letting it stabilize at exactly horizontal before clamping. I might have expected a lower readout if my knots had slipped (they don't appear to have) or even from an hour passing, but I don't get higher. Is RacquetTune not that accurate?

Also: much appreciation to the TW stringing community, particularly Irvin and YULitle, for all the resources you guys put out. There's no way I would have started stringing my own racquets if I hadn't been able to learn so much first, but now I see that it can indeed be done. Thanks.

 

[dancraig]

If these were your first two racquets, and both measured 2-4 over....you did a really good job.

 

[Irvin]

AJB you may have done a great job but all this tells me is RacketTune doesn't work. All any of these devies is going to be able to tell you is relative tension and not actual tension. Different strings at the same tension could give you different results and differnt strings at different tension could give you the same result.

What these devices do well is give you relative tension loss. If you device reads x amount and you know the relative tension drops to let's say 80% of x you don't like it any more when you get to 85% it is time to restring. I would take the reading after you string the racket and then daily until you get to the point where the string breaks or it's too loose. Then you know the point when it is time to string your racket.

Irvin

 

[SW Stringer]

After stringing my first two racquets using my new Klippermate, I checked the tension using RacquetTune. Within the hour - no play. To my surprise, the readout showed a tension between 2-4 lbs. higher than where I'd set the dropweight. (Yes, I had the Klip properly set up and had all the right specs put into RacquetTune for head size, string pattern and so on.) Can anyone shed some light on why this might be? I was meticulous about setting the dropweight correctly and letting it stabilize at exactly horizontal before clamping. I might have expected a lower readout if my knots had slipped (they don't appear to have) or even from an hour passing, but I don't get higher. Is RacquetTune not that accurate?

Also: much appreciation to the TW stringing community, particularly Irvin and YULitle, for all the resources you guys put out. There's no way I would have started stringing my own racquets if I hadn't been able to learn so much first, but now I see that it can indeed be done. Thanks.

RacquetTune uses the frequency of the stringbed to calculate the SBS. Thinner string resonates at a higher frequency than thicker string at the same tension.

Here's exactly what you did: " . . . I was meticulous about setting the dropweight correctly and letting it stabilize at exactly horizontal before clamping. . . " The net effect was a huge prestretch on the string since you obviously took a lot of time to tension each string - maybe 30 seconds or so I'm guessing. This long stetch time thins out the string especially on very ductile strings (Gamma TNT for example). So you may have started with 16 gauge string and ended up with a 16L or 17 gauge finished product.

To test this theory, successively plug in a smaller number for the string diameter in the app until you get a result that more closely matches the actual tension used. If you have some calipers measure the installed diameter of the string. Both these tests should give you some insight into your process. Hope that helps.

 

[AJB]

SW, thanks - the possible effect of the long dropweight time crossed my mind as I was working, but I didn't know what to make of it. I've read elsewhere that it's important to let the weight settle until it's truly level, and, being new, it often took me 3 or 4 times per string to feed exactly the right length into the string clamp jaw so that the weight would drop to level. I was using the free "synthetic gut" that came with the Klip just for practice - maybe it's especially ductile. What do you recommend as a good way to resolve this (besides just getting better)? If I try to avoid a long pre-stretch, I may not be able to feed in the right length to get a level drop, but if I'm a bit off with the feed-in length, I'll have to re-do and feed in less or more string until the weight drops level.

 

[leafscat]

I have also tried the Racquettune App and so far find it very consistent in its readings. I have also found though that it reads higher than the tension I used to string the racquet. I am also using a dropweight. I have measured using the provided string density factor based on string type and gauge, and I also have tried by determining the string factor using the free string test method. Results did not change much at all.

I wonder if the author of the app used a lockout machine to test the frequencies and if that would make a difference for those of using constant pull? If you look at the user guide on testing strings the photo shows a dropweight machine...so I would assume that is what was used throughout. Shooting down my own hypothesis ;-)

In the end I plan to use it as outlined by Irvin and utilize the initial reading as a baseline and not worry too much about it otherwise.

 

[jhp49]

Could it be that the markings on the drop weight bar are off? What is the best way to check the accuracy of a drop weight? The usual digital fish scales won't work. If you attach th escales like you do on an electric or lock out machine, the drop weight just drops to the table.

 

[Kevo]

Could it be that the markings on the drop weight bar are off? What is the best way to check the accuracy of a drop weight? The usual digital fish scales won't work. If you attach th escales like you do on an electric or lock out machine, the drop weight just drops to the table.

Why wouldn't a fish scale work? Just attach one end to a frame support post and put a string on the other. Make sure the string doesn't slip and it should be fine.

 

[SW Stringer]

SW, thanks - the possible effect of the long dropweight time crossed my mind as I was working, but I didn't know what to make of it. I've read elsewhere that it's important to let the weight settle until it's truly level, and, being new, it often took me 3 or 4 times per string to feed exactly the right length into the string clamp jaw so that the weight would drop to level. I was using the free "synthetic gut" that came with the Klip just for practice - maybe it's especially ductile. What do you recommend as a good way to resolve this (besides just getting better)? If I try to avoid a long pre-stretch, I may not be able to feed in the right length to get a level drop, but if I'm a bit off with the feed-in length, I'll have to re-do and feed in less or more string until the weight drops level.

AJB if feel your pain. Having strung nearly a thousand racquets over a ten year period with a Klipper I did develop a knack for how much slack to put into the gripper. However the biggest trick to reducing tensioning time is learning to partially lift the rod and either push or pull a small amount of slack through the gripper without having to completely unload the gripper and redo. This allows you to quickly settle into ''nearly level" quickly after a minor adjustment. By "nearly level" I mean within plus or minus 10 degrees of level which is within 1.52% of reference tension. Using the push/pull technique you should be able to tension a string in 5 to 10 seconds. My best time ever using a Klipper was just under 20 minutes - including removing string, mounting, installing string, and dismount. Good luck.

 

[jhp49]

Why wouldn't a fish scale work? Just attach one end to a frame support post and put a string on the other. Make sure the string doesn't slip and it should be fine.

I've tried this with a gamma calibrator. Even though the drop weight is set for 50 lbs, the weight drops all the way to the table. AN electric or lock out stops at the pounds you set on the lockout or electric tensioner. A drop weight depends on the string and fish scale/calibrator stopping at the desired tension and the bar leveling out. You can't set a desired weight on the fish scale or calibrator to see if the bar stops at level.

 

[SW Stringer]

I've tried this with a gamma calibrator. Even though the drop weight is set for 50 lbs, the weight drops all the way to the table. AN electric or lock out stops at the pounds you set on the lockout or electric tensioner. A drop weight depends on the string and fish scale/calibrator stopping at the desired tension and the bar leveling out. You can't set a desired weight on the fish scale or calibrator to see if the bar stops at level.

Simply adjust the slack in the tensioner until the drop weight bar is level. Read the scale. If the bar hits the table then you have too much slack. Remove enough slack until the bar IS level.

 

[TBrady]

AJB you may have done a great job but all this tells me is RacketTune doesn't work. All any of these devies is going to be able to tell you is relative tension and not actual tension. Different strings at the same tension could give you different results and differnt strings at different tension could give you the same result.

What these devices do well is give you relative tension loss. If you device reads x amount and you know the relative tension drops to let's say 80% of x you don't like it any more when you get to 85% it is time to restring. I would take the reading after you string the racket and then daily until you get to the point where the string breaks or it's too loose. Then you know the point when it is time to string your racket.

Irvin

You know his machine could be overshooting the tension to right? I find that app to be very accurate. And for a dollar it can't be beat.

 

[AJB]

Thanks again SW. I started to get the hang of feeding more or less string into the jaws towards the end of my second racquet - still quite a way to go but I think I know what you are suggesting. And as Irvin says, dropweight or pull tension is ultimately a reference, so I can still use Racquettune to benchmark whatever tension I set and monitor tension loss after that.

 

[Irvin]

You know his machine could be overshooting the tension to right? I find that app to be very accurate. And for a dollar it can't be beat.

Totally agree with you but the point I was trying to make is it is all relative. The tighter the string the higher the frequency. Different strings have difference resonant frequencies.

And for $1 you're right you can't beat it. I guess your phone was free.

Irvin