Losing tension after clamping down string and releasing the pull


As you can see in the video, the string loses considerable tension (10-15 lbs) after releasing the tension pull. This happens no matter how tightly I grip the clamps on the string nor how much I tighten the clamp base to the board. The base clamps do not move at all, it's the clamp itself that moves. Is this tension loss normal and if not, what is most likely the problem? The clamp? Clamp base?

Stringing machine is an Eagnas Hawk 800
 

am1899

Hall of Fame
Did you lock the base in that video? Or did I miss it? Anyway, some drawback is normal. How much depends on your machine, quality of clamps and bases, etc. (assuming the clamps and bases are clean, adjusted and functioning properly). By the way, with a lockout tensioner, the sooner you clamp the string after the tension head locks out, the better.
 

Karma Tennis

Hall of Fame
@Arran Andrews, I have pretty much the same machine as you do, except that I've replaced the original clamp bases and string clamps with different new ones.

I see much the same thing you do even with the new kit. The amount of drawback depends on the string and the reference tension I set. Obviously, the higher the Ref. tension the more noticeable the drawback.

As @Herb says, quite normal and most of the drawback will be recovered on the next pull.

One way to reduce the drawback is to pull ref. tension on every string two times before clamping the string. There are a few videos on youtube which demonstrate this. The StringMeister @Irvin has put up a great video about it which I recommend you seek out and watch.

And I also agree with @am1899. With your machine, crank at a quick consistent pace and clamp the string as quickly as possible after the tension head locks out.
 

Kaelhdris

New User
And I also agree with @am1899. With your machine, crank at a quick consistent pace and clamp the string as quickly as possible after the tension head locks out.
I'm not sure what you hope to achieve by clamping the string as soon as possible, whether you lose tension before or after the string is clamped, the absence of constant pull means you'll lose tension either way. I'd also advise to pull at a slow consistent pace to minimize this tension loss.
 

Irvin

Talk Tennis Guru
^^I agree with @Kaelhdris when you tension and hold with a LO machine it makes no difference how fast it slow you clamp the string. The tensioner once it locks out is working like a clamp. With a CP machine before you clamp the tensioner continues to pull and the string is stretched more and more.
 

am1899

Hall of Fame
IMHO, if you’re waiting around to clamp the string with a LO, you’re introducing inconsistency into the job. Other than the pull (which I agree slower is better - so long as you’re consistent), I’ve had my best results with a LO stringing at a quick, consistent pace, but not so quick that I would be prone to making errors. My .02.
 

Irvin

Talk Tennis Guru
IMHO, if you’re waiting around to clamp the string with a LO, you’re introducing inconsistency into the job. Other than the pull (which I agree slower is better - so long as you’re consistent), I’ve had my best results with a LO stringing at a quick, consistent pace, but not so quick that I would be prone to making errors. My .02.
What difference does it make if you hold the string with the tensioner or hold the string with a clamp?
 

jwocky

Rookie
If I understand @am1899 correctly, one cranks at whatever pace one can replicate consistently, but then minimizes the variation between string pulls by clamping quickly and releasing the string from the tension head. This will provide consistency in the associated machine "pre-stretch" that occurs in the string between the frame and the tension head for mains L2/R2 to the outermost.

If my understanding is correct, then that is how I was taught a few decades ago.
 

Irvin

Talk Tennis Guru
If I understand @am1899 correctly, one cranks at whatever pace one can replicate consistently, but then minimizes the variation between string pulls by clamping quickly and releasing the string from the tension head. This will provide consistency in the associated machine "pre-stretch" that occurs in the string between the frame and the tension head for mains L2/R2 to the outermost.

If my understanding is correct, then that is how I was taught a few decades ago.
if you were talking about a constant pull I would agree with you but not on a lockout.
 

am1899

Hall of Fame
What difference does it make if you hold the string with the tensioner or hold the string with a clamp?
Doesn’t matter to me one way or the other.

For me, if I clamp the string right after the tension head locks out, it is procedural, rhythmic, and easy to repeat - all of which would seem to me to be helpful in the pursuit of consistency.
 

Karma Tennis

Hall of Fame
I'm not sure what you hope to achieve by clamping the string as soon as possible, whether you lose tension before or after the string is clamped, the absence of constant pull means you'll lose tension either way. I'd also advise to pull at a slow consistent pace to minimize this tension loss.
@Kaelhdris, Thanks for the advice. However, I've now strung around 200 racquets on my LO machine. I have experimented with various process and different strings, different cranking speeds, different clamping times, tensioning strings multiple times, etc. etc.

In my situation, faster cranking and faster clamping off produces much more consistent results that are always closer to my desired string bed stiffness numbers measured straight off the stringing machine.

In my case a slow cranking speed actually increases the tension loss significantly and I end up with a sting bed that is much looser that expected.
 

Karma Tennis

Hall of Fame
@Irvin has already discovered how to create a Cold Fusion reaction with his Mighty Sensor.

Won't be any more power blackouts in Georgia when Irvin is done!

And with all that extra electricity on hand, he will be able to string up even more racquets, and make even more videos than ever before
 

Wes

Semi-Pro
I suspect someday one of you is going to split the atom with your stringing machine....
Already done.
Pretty sure the Hadron Collider was initially a stringing machine. ;)
Early Tecnifibre model, if I remember correctly (wait... or was it Babolat? o_O).
 

Karma Tennis

Hall of Fame
I must respectfully disagree. Irvin doesn't have a Mighty Sensor, he has a star 5. While the Mighty Sensor is like a nuclear reactor, the star 5 is a Honda generator.
But doesn't the Star 5 have a Sensor as well?

Otherwise, how does it know when to beep?
 
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