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View Full Version : Pre-stretch (not again!?)


David Pavlich
06-22-2004, 11:15 AM
Here's something I was thinking about that maybe my fellow professionals would like to comment on:

When I pre-stretch a full length of string, I do it for a set amount of time, which is measured in seconds. However, when someone pre-stretches on a machine, the length of time for the "pre-stretch" is a matter of a split second.

If someone has the capability, I'd like to see the stiffness of a stringbed that has had no pre-stretch, full length pre-stretch, and machine pre-stretch. That would make for an interesting comparison.

David

!Tym
06-22-2004, 12:05 PM
That's true, I've often wondered just how effective machine pre-stretch can really be. After all, like you said, it's not like it's pulling over at an increased tension for enough time to really make a substantial difference.

Eug
06-22-2004, 08:06 PM
And dont forget that the machine pre stretches only a short length of string. I think machine pre stretch is all bull.

!Tym
06-22-2004, 10:08 PM
The USRSA review of the original Wise tension head, the Ektelon model, said that they're tests revealed absolutely no difference in final tension or reduced tension loss. The Wise tension head's pre-stretch function is like most machines', it pulls tension above the reference by a bit then just backs back down. To be honest, I don't see that having that much effect, it's ever so briefly that it is *slightly* overtensioned.

I think some Gamma electronic machines machine prestretch differently. It's a slower method, but I bet it probably has more effect. The Gamma machines pull to the higher tension, and then drop back down to ZERO, and then repull again, all the way to the reference tension. That probably has more of a genuine effect in my opinion, as it's basically a form of double pulling. Like if you pull tension twice on a crank tensioner you effectively make the string bed feel tighter, same thing here I bet. It's like doubling the pulling time, and I think the best form of prestretch and hence reducing tension loss is NOT pulling over the reference tension slightly, but rather increasing the time the string is under tension. Ideally, most strings should be pulled for 5 to 10 seconds or so to get rid of the creep, but not many people actually have the patience or time to cound one Mississippi, two...if you know what I mean. Me, myself, and I included in this admission.

!Tym
06-22-2004, 10:12 PM
I've heard some experienced, elite stringers say that in their opinion machine prestretch is worthless and doesn't do anything.

Yet, I've also heard some feel that it does make a slight difference.

In any case, it's debatable and I havn't heard anything conclusive on either side, just general impressions. But if your machine comes with it, why not? Probably not actually necessary, but it doesn't hurt to have it when that ultra picky customer driving the new Porsche comes in and says that he lost his last match because YOU didn't machine prestretch his Babolat VS Gut 19L guage!!! Ha-ha, need I say more?