Most racquet technicians are familiar with the Stringmeter device. The Stringmeter uses a torsion spring to measure the tension on a given string. It has three (3) modes; stringers free string scale, Kg scale for strung racquet, and Lbs scale for strung racquet, with a string gauge scale for 15, 16, and 17 gauge string. Sounds simple enough, right?
Sure, but the Stringmeter is probably the most misunderstood device known to man, or in this case racquet technicians. Why? Simple. What does the number mean and how do you keep it a secret from your customer! One thing at a time, please. First, the string is inserted between two posts on the underside and the device is rotated until the string is aligned in the string gauge slot. Simply read the number on the gauge and that’s it. This number is accurate and indicates the tension in that specific string. Why would you want to keep this a secret from your customer? Because it is probably not going to match the tension the customer asked for. You could explain it but that may not satisfy the customers curiosity.
More about this later but let me tell you how I use the Stringmeter and why it is the only device that does what I need. When I evaluate a stringing machine one of the most useful pieces of information is how much tension is left in the string with only the main strings in the racquet. With only the main strings in the racquet I find that most machines will allow the racquet to distort considerably, simply get wider, allowing the string tension to disappear.
So, each string is measured with the Stringmeter and this is recorded. But wait! Recently I was comparing numbers with my colleague and was surprised when there was a huge variance between his numbers and mine. He sent me his Stringmeter and it was instantly obvious what was wrong. His Stringmeter had been re-designed to make the tested number be more acceptable to the racquet technician and the customer! So now instead of the Stringmeter reading “0” when there is no tension on it, it now reads “17”, or thereabout, with no tension on it!
So, for my purposes the new Stringmeter is no longer valid.
Now back to the good stuff. The Stringmeter, even the new design, can be used as a reference tool to measure tension loss over time. Check the tension in the same location and be sure you are exact in the location of the string in the gauge slot. When checking the cross string you will notice a big difference in tension relative to the main string. Many say, and believe, this is a function of friction between the main and cross string during installation. Nope. This difference is because the racquet has distorted and has used the cross string tension to “pull” the racquet back into shape.
I will continue to use my “old” Stringmeter for my specific purpose but I would suggest any racquet technician invest in a device that removes any operator influence. The Beers ERT300 is a good, portable, inexpensive (relatively) device that returns a string bed stiffness not an individual string tension.