Category Archives: Testing Devices

And the winner is…Head FXP 17

 

Head FXP is a string that seems to be largely overlooked and I am surprised after seeing the results of the installation and testing!

String NameCategoryGaugeUltimate Tensile Strength/LbsKnot Strength/LbsCountry of Origin
Head FXPMultifilament - Nylon17165.993.4Japan

Both the tensile strength and knot strength are exceptional and the graph shows that this string is very “elastic” which is a good thing for tennis racquet string but sometimes just not considered.

Head FXP 17

The area under the solid red lines is considered a stress-strain curve and indicates the “elasticity” of string by how close the lines fit from 0 to 50 three (3) times.  A perfectly elastic material would be one line even though it went through three (3) cycles.  What you see here is quite good and one of the reasons it is the winner!

String Evaluation Program

Racquet Quest, LLC has for years been doing the extensive evaluation of racquets and string for the benefit of our client’s customization requirements.

Now we are making this evaluation “program” available to anyone that wants to dig deeper into the workings of the string in the racquet!

This is serious stuff and requires significant resources but it is worth it!

Please contact us of you would like to take advantage of our evaluation program!

Take a look at the String Evaluation Program!

 

 

What Can String Failure Tell Us?

Well, in the simplest terms, failure tells us it is time to have the request strung! However, there may be subtleties in string failure that can help us in our quest for tennis racquet performance.

Such as?

Is the failure shear related or tensile strength related? Was friction the major contributor to the failure? Where did the failure occur (on the racquet, not the court)? Was the failure during play or in the bag?

Shear-related failure is when the string breaks very near the racquet frame. This failure is called a mis-hit or shank! It is like cutting the string with a pair of scissors!

Shear Failure

Friction Failure

Friction failure is caused by just that, friction!  Friction is caused by the string moving on each other. That rubbing creates friction and notches the string where it will fail.

If the racquet failed during play and it is not shear-related, the tensile strength of the string was exceeded. If a string has a tensile strength of 120 pounds and the tension is 60 pounds leaving 60 pounds to be used to hit the ball. Some big hitters can generate at least that much force on a solid forehand!

The graphs show the tensile strength and relative elongation of different material.

This graph shows the tensile strength of the string to be about 115 pounds.  Given the movement of this string-on-string, the frictional notching can contribute to relatively early failure based on the hitters force.

This graph shows the tensile strength of the string to be about 155 pounds but it has to travel (stretches) further to reach that force.

So, you can see, with this information we can make better decisions when asked to suggest a string, or strings, for a client!

Our Mission

The “Questron” has Arrived!

If you have been following Racquet Quest online and with the podcast, you know we are very fond of data!  In keeping with that “fondness,” we have received our newest testing device, which I have named “Questron.”

During the last week, we have spent time getting Questron set up to do the kinds of testing we think is important for the tennis player, the racquet technician, and anyone else that cares about numbers!

It will be about another week before posting any data because we are “tweaking” some connection points, cycle settings, and refining the data’s graphing.

We have over 400 strings to test; however, we will eliminate many of those strings not relevant to today’s tennis player.

Let us know if there is a string you are particularly interested in. If we have it, we will test it!

Even in the “testing” phase, we are discovering interesting facts about strings that will help us put together the best setup for you!

This is the “base” Questron.  Future versions of this device will incorporate the “Power Potential,” “In-Plane Stiffness,” and “Dynamic Stiffness” testing that is currently done on other equipment.