Category Archives: Elongation
Another 1000 Word Picture!
What happens to a string if it gets scuffed or slightly damaged in terms of properties?
We know the string will not go in the clients’ racquet, but how bad is it, really?
The chart below shows exactly what happens to each string until both fail. We can see precisely how the scuffing affects the string. Both strings behave nearly the same through the three (3) cycles to 50 pounds. We then see that the scuffed string gives up a little earlier than the clean string by about 15%.
So, what’s the Difference?
However, the failure force for both of these strings is very high! Only a handful of strings we have tested exhibit this tensile strength.
So we know this string would never be used in a client racquet, but you could certainly use it for some “experimentation!” And, of course, depending on how many and where the “rough” spots are you can cut that portion away!
A Picture is Worth a 1000 Words?
Yesterday @ the World Headquarters was full of interesting stringing! So we decided to do some testing of some of the strings that were just waiting to be broken!
The chosen strings are Ashaway MonoGut ZX Pro 17, Tecnifibre Triax 17, and Volkl V-Star 18—three totally different materials. Our purpose is to determine a string’s properties before it goes into a tennis racquet. Our testing quantifies these properties, and then the “feel” component comes from the player.
A 1000 Words?
We normally do not do more than two (2) overlays because it is a little messy, but these strings begged to be compared, so here it is!
Our Questron can cycle automatically, so the stop points are pretty precise. All strings are cycled from two (2) pounds to fifty (50) pounds and then until they fail or ultimate tensile strength (UTS).
In the Displacement axis (X), the shorter the distance in mm to 50 ponds, the stiffer the string. The straighter the line is to fail, the more consistent the feeling until failure.
The testing confirms that Tecnifibre Triax does contain some stiffer fibers. The other strings are monofilaments, so there are no fibers.
Racquet Quest uses a bunch of each of these strings for obvious reasons and, of course, depending on the player.
Pre-Stretching String…Why and How?
Every string we put into a tennis racquet is “pre-stretched”…not just sometimes but every time! This is an old post but worth seeing again I believe.
Why?
Pre-Stretching slows down the “creep” process that reduces string bed stiffness, (tension loss) and to feel what the string is doing while being stretched, and making some strings easier to handle during the stringing process. Some strings stretch a lot and some strings don’t. We can tell a lot about how the string should be handled (and the application) based on pre-stretching.
How?
Most stringing machines have a pre-stretch feature, including ours, however, we prefer the entire length method. All forty (40) feet of it! If you have a room, that is forty feet long, or a perfect outdoor spot use it!
The proper tools and proper technique make pre-stretching an easy and performance-enhancing procedure.
Parallel Plier
The object is to pull the string straight. The plier needs to grab the string as shown.
The arm and wrist should be in the neutral position as shown so the stress is on the string, not your body.
The other end of the string can be secured through a hole with a “starting clamp” as you will see below. These clamps are rated to hold 90 pounds so it is not in danger of letting loose!
Tree Hole
We probably hold the string at tension for 30 to 40 seconds after applying four or five quick short stretches.
For many years we used a high-tech device to measure how much force we apply during the stretching procedure. The force we apply is between 35 and 40 pounds using this rig…
This scale is rated to 100 pounds. The string is inserted through a hole in the bracket and secured by a starting clamp, then using two hands grab the handle and begin to stretch the string while reading the force on the scale. After using this device for a while it will become a matter of “feeling” not measuring the force.
Stretch Scale
Monofilament Material Comparison
Most monofilament tennis strings are polyester, a blend of polyester, or PEEK.
As you know, we believe there is no wrong string, just wrong applications. The graph will show the comparative stiffness of three (3) materials. The string is pulled at a rate of 1mm per second. The resultant spreadsheet for this particular test is about 5300 rows long.
With our spreadsheet, we have access to every mm of data. Maybe sometime we can post some of the individual data points.
Blast is polyester, V-Star is a unique blend of material (I do not know what it is), and MonogutZX is PEEK (polyetheretherketone).
The graph shows the cycle from 0 to 50 pounds three (3) times, then to failure (UTS). The quicker (shorter distance) the string reaches the 50-pound mark, the stiffer it is. MonoGut ZX did not fail in the 180mm excursion. You can see, in this case, the stiffer string fails at a higher force but shorter excursion.
Stiffer strings deliver less power and have a higher shock value. The midrange stiffness shows exactly what would be expected, and the softest string also indicates expected results.
Now for some GOOD news!
It seems that I am recovering from this cold or whatever it is, so now we can return to a relatively normal schedule!
I want to start with some comments from Willie B. regarding string. After you read Willie’s comments, we can talk about the string and why it does what it does: to allow players of any level to play without discomfort.
Here is from Willie:
“FYI, my inability to play tennis more than 1-twice a week due to the pain for over 4 years impacted my game. The last time I was ranked was 5.0, but now at 47, probably more like 4.5 (No tournament for the previous 5 years)
The good news is that with the feel of those strings, I can hit back (I practiced with a top player last Sunday, and he even felt it as I am not scared to go big… I have played with him for over a decade)”.
Willie’s racquet technician is Henry Hamels of String MD. Thank you, Henry, for sharing!
If you have not already guessed, the string material is PEEK, polyetheretherketone, which was marketed as Zyex by Ashaway under the MonoGut ZX and ZX Pro models! This monofilament format offers an alternative to stiffer monofilament strings while providing, in most cases, better performance and durability!
- The raw material is expensive.
- Some
racquet techniciansstringers simply don’t know how to handle PEEK.- The high elongation of PEEK is a surprise to the first-time stringer.
- Marketing hype is not strong.
- Very few players and stringers know about this alternative.
- See Marketing Hype above!
- Stringers may have had a poor experience before and are wary.
- The material does not change shape; therefore, knots are not as tiny as some stringers prefer.
- PEEK will “tighten” its own knots.
- Beginning stringers may over-tighten the knot, causing failure…never to be used again!
- Currently, the material is available in two (2) colors, tan and black.
- MonoGut ZX is 16 gauge
- MonoGut ZX Pro is 17 gauge
Depending on the player’s tennis intentions, we may start them on PEEK at age nine (9) but no later than twelve (12).
Thank you, Willie, for your comments!
To see if this material will benefit your game now and for the long term, ask your racquet technician.
- Please text us if you need additional information: 407.491.4755
- Comment on this site, and we will respond to specific questions.
- If, based on our player history, your application may not be the best, we will tell you.
- Very beginning players and those players experimenting with various strokes creating mis-hits need to be recognized.
Racquet Quest, LLC
