Category Archives: Knot Strength
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.
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.
An Inside Look at String Evaluation
In this series, we will look at the various characteristics of tennis string without the tennis racquet!
Racquet Quest evaluates every string we use plus strings submitted from other sources. These evaluations are “No Prep” and “Prep”, which simply means the Prep string has been pre-stretched in the entire length. It has not been through a tennis racquet…yet!
The following images represent a string that has not been “prepped.” After these plots are fully understood we will do the same string in the”prepped” format to see if there is a difference.
Ultimate Tensile Strength
What we notice immediately is the string is very “soft” as seen in the deflection of 47.8 mm to reach 50 pounds. Also, the elasticity, the ability to recover to the original length, is fairly low.
The area under the 50-pound and 47.8 mark is the stress/strain curve that shows how the string behaves in three (3) cycles. The load and number of cycles can be changed.
The long run (linearity) from the 50-pound mark to failure is quite good and suggests consistency.
The UTS, the ultimate tensile strength, of 127.1 pounds is good for this thin string.
The following plot shows the knot strength of this string.
Knot Strength
This plot is overlayed on the previous image so a quick comparison can be made. It is common for knot strength to be lower than un-knotted string. Knot strength is primarily important to the person tying the knot. Knots rarely fail after they are successfully tied. Pulling a knot too tight or jerking can break a knot.
This plot says to us that this string needs to be handled carefully when it comes to knots! We would expect a knot strength of at least 80 pounds for typical monofilament strings, however, if this string exhibits extraordinary play characteristics anyone can learn to tie the knots!
Based on this information we would suggest this string for a player looking for extraordinary comfort, power, and relatively short life!
Racquet Quest, LLC
