Home » RSI magazine » Ask the Experts » Constant pull vs. lockout

Constant pull vs. lockout

Q: I am in the market for a stringing machine and am having difficulty making sense of a couple of issues. One of them is constant-pull versus lockout. I have read on the web that lockout machines do not offer the consistency of constant pull machines because with the lockout machine (1) the string loses tension after you have tensioned it but before you have clamped it, and (2) the tension depends on how fast you move the crank. On the other hand, you may lose a little tension before clamping with an electric constant-pull machine if the tensioning system is not sensitive enough to compensate for small tension drops. Also, with constant-pull machines, there may be some inconsistency in tension if you are not consistent with the amount of time you let the string pull. The final issue is that of 360-degree rotation. Does lack of 360-degree rotation result in any lack of consistency in pulling the first two main strings or any other problem?

A: Unless you buy a really poor quality or malfunctioning machine, most of your problems with consistency are going to be due to your stringing technique, not the machine. That is to say, even though the final stringbed stiffness with a lockout machine is lower than that of a comparable constant-pull machine, this is not a consistency issue. As your technique improves with a lockout machine, your pulling speed and time-to-clamp will become more consistent.

Also, in most cases you will find there are larger consistency issues with the clamps and mounting system than with the tensioning system. Other than physical defect, the consistency of the tensioning system usually comes into play only if you don’t properly maintain and calibrate your lockout machine, as it typically will need re-calibration more often than a constant-pull machine.

In other words, for any reasonably competent stringing machine, the machine itself is almost certainly going to be more consistent than the stringer.

As for 360-degree rotation, again, this doesn’t affect consistency as much as it does speed. In fact, you stand to gain a bit of consistency by having the tension head up at the level of the stringbed. Whichever you choose, eventually that system will seem “normal” to you, and as your comfort grows with your machine, your consistency will improve.

See all articles by Greg Raven

From the November 2008 issue
Permalink