Constant pull with Wise - overpulling?

#1
I am using Wise with Gamma Progression X-ST. I get overpulling with some pulls using constant pull. When using constant pull at 26 kg with Alu Power, tension (as indicated by Wise display) when pulling goes to 26 kg, then beeps, then sometimes goes up to 27 kg, then goes down to 25.8 kg for example and then comes back to 26 kg. Are such fluctuations normal?
 

Dags

Professional
#2
Yes, this is normal behaviour. The best way to maintain consistency as a stringer is to follow the beep rather than the display: once it beeps that's your cue to clamp.
 
#3
Yes, this is normal behaviour. The best way to maintain consistency as a stringer is to follow the beep rather than the display: once it beeps that's your cue to clamp.
The whole point of constant pull is that it keeps pulling adjusting the tension continiously. If clamping right after beep - that is basically replicating lock out mode. Still puzzled...
 
#4
@Jurijs - here's a neat experiment for you. Next time you string a racket, switch your Wise to lockout mode. You'll be shocked at just how quickly tension drops. You can't clamp that quickly on a lockout to replicate a constant pull. Also, your Wise may overshoot but it does constantly pull adjusting its pull to keep tension within a tenth of a pound or so. Well enough that you can't tell. With higher end electronics, you don't have the stutter pull, the adjustments are solid.

But....there is absolutely nothing wrong with a lockout. IMO based on my experience, it's all what you get used to.
 
#5
LO mode on a Wise is not like pulling with a LO machine. A Wise in LO mode pulls and stops. A LO continues to pull even after locking out because the tensioning spring is still holding tension on the gripper unles your tension brake is slipping and the tensioning spring fully returns to the rest position.

An electronic machine (constant pull) will pull somewhere past reference tension and stop. Then a the string relaxes the tension as sensed by a load cell will start the pull again and stop. This process repeats constantly but the tension will take longer with each cycle to kick in because as the string relaxes over and over again it will take longer to relax to the point where the tension starts pulling again.
 
#6
I am using Wise with Gamma Progression X-ST. I get overpulling with some pulls using constant pull. When using constant pull at 26 kg with Alu Power, tension (as indicated by Wise display) when pulling goes to 26 kg, then beeps, then sometimes goes up to 27 kg, then goes down to 25.8 kg for example and then comes back to 26 kg. Are such fluctuations normal?
Yes it is normal but going up a Kg (2.2 lbs) sounds like a lot to me.
 
#7
LO mode on a Wise is not like pulling with a LO machine. A Wise in LO mode pulls and stops. A LO continues to pull even after locking out because the tensioning spring is still holding tension on the gripper unles your tension brake is slipping and the tensioning spring fully returns to the rest position.
This is not true, the part about a lockout continuing to pull. It is conjecture on @Irvin’s part.
 

MathieuR

Professional
#8
A LO continues to pull even after locking out because the tensioning spring is still holding tension on the gripper unles your tension brake is slipping and the tensioning spring fully returns to the rest position.
This is bull! Has been extensively discussed and busted.

Edit: the cheapest "real cp" (without overshoot) is the automatic dropweight
 
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#9
Thanks for comments! My biggest concern is exactly if such oveprulling by 1 kg just too much and if there is a problem with my Wise tensioner.

I have filmed several test pulls today at 26 kg - some are ok (firts one in the video), but other seem odd, as tension rises to 26,9 kg eeven before coming down to reference tension (secnd and third pulls in the video).

What can affect such behaviour of tensioner? Should I do some maintenance? Any similar experience?

 
#10
One thing worth mentioning - I started noticing overpulling problem after I first strung a racket with pre-stretching function on. Wondering if that might somehow affected machine...

UPD: Made more tests and looks like I have this problem with tensions in the range of 25,5-26,5 kg. Other tensions work fine. But within that specific range Wise seems to make too harsh adjustments while pulling. I did most of my frames at 25-26 kg. Wise official response - from several videos sent to them - it is within tolerances and hence ok, but can send for recalibration, which practically is a pain for me...
 
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#11
One thing worth mentioning - I started noticing overpulling problem after I first strung a racket with pre-stretching function on. Wondering if that might somehow affected machine...

UPD: Made more tests and looks like I have this problem with tensions in the range of 25,5-26,5 kg. Other tensions work fine. But within that specific range Wise seems to make too harsh adjustments while pulling. I did most of my frames at 25-26 kg. Wise official response - from several videos sent to them - it is within tolerances and hence ok, but can send for recalibration, which practically is a pain for me...
try switching from Kg to lbs and see if you notice the same thing. Electronic tenders are not constant pull machines no matter what anyone tells you. An electronic machine has a high tension and low tension and is measured by a load cell. When the high limit is reached the tension stops pulling. As the string relaxes the tension drops and (with nothing in series with the string to maintain a pull like a spring tension will drop fast) when the low tension is reached the tensioner pulls again.

Switch to lbs it only takes a second and may resolve what you think is a problem. You don’t have to convert from 26 Kg to lbs the machine does that for you. I doubt there is anything wrong at all.
 
#12
When Brett was at Gamma he used to say to always use a spring loaded tension gauge to measure tension and not a digital luggage scale. The reason for for is the spring in the calibrator acts like a shock absorber and maintains a constant tension on the string by pulling back as the string relaxes. A load cell does not work that way and as the string relaxes tension falls immediately. You Wise readout is looking at the output of a load cell, therefore tension falls and rises very fast.
 
#13
@Jurijs, I really don't think you have a problem. I think you'll have a problem when you get an error code on the display of your Wise. :) I'd continue on and not worry about it. If it is overpulling a kg, it won't hurt anything. I'd use it until it had a hard fail or you notice something in the results; i.e. the string bed.

I sent my first Wise in after about 5 or 6 years to get it checked out. I figured it was due a PM visit. Dan at Wise installed a new load cell, re-calibrated and freshened it up. As I remember, it was only like $75 + shipping. I thought that was a good deal considering.
 
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