# Thread: Stringbed frequency to monitor string tension

1. Originally Posted by kwun
i have to disagree. the head will exand and contract under heat/cold and result in a bigger/smaller oval.
You're correct.

Coefficient of linear thermal expansion of pure graphite is 4.4 x 10^-6 in/in°F, and for aluminum is 12.3.

So for 15C change is 27F change. Plug in 27 in for frame circumference.
Results in 0.0032 in, or 0.081 mm.
Somehow that is very negligible.

2. Originally Posted by visor
You're correct.

Coefficient of linear thermal expansion of pure graphite is 4.4 x 10^-6 in/in°F, and for aluminum is 12.3.

So for 15C change is 27F change. Plug in 27 in for frame circumference.
Results in 0.0032 in, or 0.081 mm.
Somehow that is very negligible.
hehe. so there IS!!

i agree though, it is negligible.

but how do we explain your observation then?

3. Originally Posted by visor
You're correct.

Coefficient of linear thermal expansion of pure graphite is 4.4 x 10^-6 in/in°F, and for aluminum is 12.3.

So for 15C change is 27F change. Plug in 27 in for frame circumference.
Results in 0.0032 in, or 0.081 mm.
Somehow that is very negligible.
Have you tried it? Did you measure it with your electron microscope? Did you leave your favourite racquet out on the cold, cold mountain for a day, then slow-roasted it over the barbeque, and measured the difference?

If everything in the real world could be explained through physics and theorems and stuff, we would all be visor than we are...

4. Lol! Lemme check the coefficient for cobalt and see if I need to subject it to extreme temps...

5. Originally Posted by kwun 2049843
hehe. so there IS!!

i agree though, it is negligible.

but how do we explain your observation then?
I don't know... I'll check vs850 tonite.

6. 2 rackets. NS9000, AT900P

both strung with NBG98 @ 23.8/26lbs

0hr:

NS: 1212.3Hz
AT: 1193.4Hz

3 hrs:

NS: 1188.4Hz
AT: 1162.1Hz

17hrs:

NS: 1177.0Hz
AT: 1150.4Hz

7. VS850 at 24 lb on SW30 from 9 months ago, rarely played

1027 Hz at 20C
1023 Hz at 5C
1027 Hz at 20C again

So, there is a trend. Tensions fall off a tad when colder. But this is only like 0.1 lb and the string material hardening with colder temp is probably more significant in causing a harder brittle feel in the cold.

Still would be interesting to see what happens in Asia going from 20C to 35C. Anyone?

8. Originally Posted by ucantseeme
SW35 with BG80 @29lbs: 1197 Hz, strung @Yonex German Open with EsPro, measurement at 6-8 hours after stringjob.
Today, at 1123 Hz. String and tension feel comfortable, powerful and are superb IMO.

9. Regular Member
Join Date
Mar 2011
Location
Posts
306
Post Thanks / Like
Mentioned
4 Post(s)
Tagged
Looking at a few frequencies provided and comparing, it seems to me like Victor racquets tend to have a lower frequency at the same tension as lets say Yonex. Could have to do with the fact that they don't fill the racquets with foam.

10. Originally Posted by blableblibloblu
Looking at a few frequencies provided and comparing, it seems to me like Victor racquets tend to have a lower frequency at the same tension as lets say Yonex. Could have to do with the fact that they don't fill the racquets with foam.
Hmmm... as I understand, the foam is placed inside the T joint, not throughout the whole frame, right? I don't think I've ever seen any foam in the frame in any of the broken rackets post mortem photos.

11. Regular Member
Join Date
Mar 2011
Location
Posts
306
Post Thanks / Like
Mentioned
4 Post(s)
Tagged
Originally Posted by visor
Hmmm... as I understand, the foam is placed inside the T joint, not throughout the whole frame, right? I don't think I've ever seen any foam in the frame in any of the broken rackets post mortem photos.
not quite sure exactly where they put it since I haven't looked at the whole thread and haven't translated what he says. Doesn't seem to be in the whole frame though. Could still have an impact on frequency though, I think.

12. If anybody hasn't got an iPhone - I can't be the only one - there's a free program called PitchPerfect that does exactly the same thing on a PC. All you need is a microphone of some kind.

Just tested a couple of strings against generated tones, and they sound spot on. Now I've got some kind of objective measure of tension loss, but this means I'm probably going to re-test everything. Thanks, OCD!

13. Interesting to see how much tension is lost early on... just tested the Adidas Power Tour 66, and it's gone from 1277 Hz to 1228 Hz in 12 hrs before it's even hit a shuttle! 3.8%, IOW.

Looking forward to seeing the "fresh" frequency of Zymax 62 at 30x31...

14. Originally Posted by Mark A
Interesting to see how much tension is lost early on... just tested the Adidas Power Tour 66, and it's gone from 1277 Hz to 1228 Hz in 12 hrs before it's even hit a shuttle! 3.8%, IOW.

Looking forward to seeing the "fresh" frequency of Zymax 62 at 30x31...
Mark, did you ever get a reading for ZM62 @ 30x31 ?

Contribution:

ZM65 @ 26x28 on NR700RP using crank machine tension tested with scales immediately before

0hrs = 1189 Hz

15. As a reference, my ZM62 @22x23 lbs ECP :
0hr = 1212 Hz

16. Originally Posted by visor
As a reference, my ZM62 @22x23 lbs ECP :
0hr = 1212 Hz
That frequency looks more like 26 lbs based on other results in this thread?!

17. Originally Posted by msitpro
That frequency looks more like 26 lbs based on other results in this thread?!
Yes, and that's the wonder of super thin strings.

Page 4 of 11 First 1 2 3 4 5 6 7 8 9 10 11 Last

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•