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Old 02-02-2013, 11:07 AM   #40
Technatic
Semi-Pro
 
Join Date: Oct 2009
Posts: 416
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Quote:
But is continuous pull really all that great? Would it be more consistent to pull for an exact length of time at an exact tension? If you answered yest you want a lockout. And there are arguments for electronics too.
If all strings would stretch in the same way the lock out systems would be quite consistent, but that is far from true. There are fast strings and slow strings and stretchy strings and stiff strings.

* The difference and stretch behavior causes huge differences in the DT value on lock out machines.
I would like to use graphs that were discussed earlier to show these differences:


This graph shows the tension in 2 multifilament nylons a fast one and a slow one.
Loss of tension in the upper graph is 17,6 lbs (out of 66 lbs) and most of the tension drop occurs in less than a second. This is a “fast string” which stretches very fast.
Loss of tension in the lower graph is 11 lbs and the tension drops quite slow. This string stretches slower, because there is more friction between the elements.
The rising graph shows that the speed of pulling is about the same.


This upper graph shows a stiff mono (2,7 % tot el) and the loss of tension is 10 lbs and the string stretches slowly.
The graph at the bottom shows a stretch mono ( 6 % tot el) and the tension loss is 13,2 lbs and the tension drops quite fast, so it is a ‘fast’ string.
So the difference in loss of tension and DT value is huge and depends on the type of string.

* The second problem with a lock out is that it actually prestretches every string, making it stiffer to play with then it is on a CP machine.
A string is prestretched when the string is tensioned at a higher tension before it reaches the actual final tension. So the strings in the graphs are prestretched at tensions which are 10 to 17,6 lbs higher than the final tension.

This changes the playability the string considerably the player will feel a stiffer string.

On a CP machine the tension in the string will not overshoot the adjusted tension by more than 1 or 2 lbs, depending on the quality of the CP system.

IMO it is impossible for a stringer to reckon with these influences of the specs of the strings.
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