Category Archives: Stress/Strain
NG Strings – Part Two: Natural Gut Knot Strength
Any string that goes into a tennis racquet is, at some point, going to be tied off using a knot. Creating a string knot is normally not an issue, however, some strings are more sensitive to this process than others.
This plot will show the relative difference between gauges, and other properties. We can see that NG17 gauge did not quite make it to the stress/strain ceiling of 50 pounds. That is why there is only a single line while the other two (2) go through the cycle before the knot fails.
This is a tough test for natural gut due to the coefficient of friction (COF) being pretty high meaning the overlapping strings are like sawing at each other as the knot is being pulled tight. The knot strengths in the 60 pound range are suitable and will not, typically, be a problem. Be very careful with values less than that, however.
Natural Gut Knot Strength
And, while we are talking about knots, we need to consider the best practices for tying off other strings on natural gut. The best practice is don’t! Find a grommet that can be suitable for tying off another material type on itself…not the natural gut. Obviously if the entire string bed is natural gut it is a good idea to find a suitable tie off on a cross string.
There are other considerations when typing off on natural gut and we will have look at these in a future post.
The power potential of the NG Strings has beed added to the String Power Potential page and can be seen here.
Just type in NG Strings in the search field if you don’t feel like scrolling!
NG Strings
Several months ago we tested some small samples of NG natural gut string. The results were not exciting so the data was not published.
Recently we tested some new versions of NG Strings, the PROV5+, and have some results to post.
First, the packaging is top notch.
Second, the two (2) 12m lengths per set is perfect, in our opinion, since all racquets should be strung using two (2) pieces of string, no one piece or ATW. There may be a manufacturing component to the 2 piece decision, also.
The “squiggles” we see in the two (2) NG Strings may be the tiny changes in the bonding agent(s) that occurs under load. We have seen this in some early Luxilon gut. We refer to it as a “break-in period”. Pre-stretching the entire piece length will reduce the break-in period.
Third, the gauge is much more consistent than previous samples.
This initial post will include stress/strain and ultimate tensile strength plots compared to Babolat VS Touch 17, our most used natural gut.
The first plot is UTS:
Natural Gut UTS
This visual tells the story but if you want the numbers they are at the failure end of each string. The stress/strain cycle shows the relative “softness” of each string. The higher the deflection the softer the string, so NG16 is the stiffest of the three and NG 17 is the softest.
We will be adding Knot Strength so check back soon the see how each string reacts to knots!
We will do several other tests before the string goes into a racquet for player feedback.
In summary this version shows tremendous improvement over the first version we tested… give it a try.
Take a Guess?
A very good player and client came into the World Headquarters Wednesday with his three (3) Tecnifibre TF40 315’s wanting to re-string. There is nothing unusual about that except this time he wanted to discuss different strings. So we did!
The final three (3) strings under discussion were:
- Tecnifibre Razor Soft 17 (current string)
- Volkl V-Star 17
- MonoGut ZX Pro 17
The first two are considered to be polyester, however, I am not sure V-Star fits entirely in that category, and PEEK is the material with the MonoGut ZX Pro name. All of the strings are monofilament.
We learned in a previous post “a picture is worth a thousand words”, so we are including a picture to help in our guessing.
Take a Guess?
Here are some basic properties of the subject racquet that may contribute to your guess
- Weight=342
- Swing Weight=327
- RDC Flex=63
- Flex Four Flex=50.8
- Grip Size= 3
We hope you will make a guess in the “comment field” below and if you do you can use the string name or the color…we will figure it out, and thank you for you guess!
Comfort is the new Soft!
Over the years descriptive terms for tennis strings have endured many mythical, and even wrong, definitions.
One of the terms we continue to hear is “Synthetic Gut”. First of all, in terms of tennis string if the material is not from a once living animal it is “synthetic!” The term “synthetic gut” was responsible for relegating “nylon™” to the very lowest of low end tennis string, however, even today Nylon™ makes up a substantial percent of the tennis string material!
Now comes “Comfort” trying to relegate “Soft” to the scrap heap!
What difference does it make? A lot. Seasoned players know what works for them and they don’t care what anyone calls it. On the other hand those just beginning or wanting to improve their game do care.
With our in-house testing device, Questron, we test every string that goes into a racquet, and every string that comes into the World Headquarters . The graphs have been posted on this site a few times but just in case you missed them here is a graph:
This graph represents two (2) polyester strings and one (1) natural string because it was handy.
In the simplest terms the quicker (shorter deflection) the string reaches 50 pounds the “stiffer” or less “soft” it is. Neither of the polyester stings are “soft” compared to the natural string, however, one polyester string is “softer” than the other polyester string but not by much.
We have tested many strings that are now available in a “soft” version and the “standard” (not soft) version.
Whatever string version you choose use it because it works for you whether is it marketed as Comfort or Soft!
Racquet Quest, LLC
