Home » RSI magazine » Ask the Experts » Equal ‘twang’

Equal ‘twang’

Q: After trying different techniques, I don’t seem to be able to get the two center mains at the same tension. I clamp the right main and add the starter clamp. I then tension the left main, clamp it, and tension 2LM. I then tension 1RM, remove the starter clamp, and move the regular clamp. I then string and tension 2RM and clamp off. This is done as shown in the stringer manual. With the four center mains strung and clamped, when I “twang” the two center strings there is a very noticeable difference. I have tried pulling the tensions with a different tension on each, I have tried clamping the higher-tensioned string in various places on the first pull, and I have even tried a double pull. What would you recommend?

A: There are two predominant factors causing your unequal tension on the center two mains.

First, when you clamp 1RM and pull tension on 1LM, you are pulling tension on 1LM, the string going around the outside of the frame, and the short section between the frame and the clamp on 1RM. But when it comes time to pull tension on 1RM, you are pulling 1RM, the string going around the outside of the frame, all of 1LM, and so on. In essence, you are pulling the two center strings under different conditions, which can lead to different results. Frankly, the difference is so small that we don’t recommend any special procedures to equalize the tension.

Second, with any machine, the moment you clamp off and release the tension head, the string starts to lose tension. It sounds as if you are using a lockout machine, because the clamps on most other types of machine are so thick that you typically do three mains on one side before catching up with the other. With a lockout machine, this tension loss will be more noticeable because of the way the string is pulled, compared to a constant pull machine. Without knowing more details, our guess is that you are seeing the difference in tension due to the additional time the 1LM has had to relax. This is assuming you don’t have a clamp slipping or some other technical defect in your machine or technique. If this is the case, instead of worrying about the tension of the center two mains right away, wait until you get all the mains in, and then compare the tensions. If everything else is okay, the two “twangs” should be much closer in pitch, as the two center mains will by that time have more similar lengths of time since tensioning.

From the March 2007 issue
Permalink