Butt Frequency vs Tip Frequency
TECH NOTE 31: A few years ago an article was written in Golfsmith's Clubmaker magazine regarding a club that Scott Verplank did not feel was matched to the rest of the set. While all the butt frequencies in the set were a perfect match they found the offending club had a different tip frequency than the rest of the set. Tip frequency means clamping the tip and twanging the butt. They searched through their semi- infinite supply of shafts and found a shaft that had both the right butt and tip frequency. Scott was very happy with the newly reshafted club.
This seems a bit over the top for most clubmakers. As a service to my customers I supply a set of tip collars for the Club Scout to measure tip frequencies. I think I've sold four in the last two or three years. Apparently most clubmakers feel as I do.
I did have an interesting experience along these lines recently. I have a driver with an Aldila 50/50 Longwood shaft in it that I really like. I was testing some SK Fiber shafts and decided to build an identical driver to my Aldila driver. The Aldila was 247 cpm D5 at 45". I assembled a 45" SK driver and it came out 249cpm with no tipping and D5, pretty close. When I went to test drive the two the SK felt very much weaker even though it was actually a hair stiffer. The SK has a long 7" parallel tip section whereas the Aldila had virtually none. I thought maybe it had something to do with this tip frequency business. There was a difference. I decide to check the butt and tip frequencies of a number (22) of different brands of shafts and see what I got. Most of these shafts were lent to me by Raven. My supply is rather limited.
I don't think there's much of a standard for measuring tip frequency so I sort of invented my own. I found a very neat and quick way to measure the two frequencies of a shaft. I used a Craftsman 200gram 3/8" chuck to measure butt frequency. With the chuck still firmly attached to the tip I then flipped it around and clamped the chuck in my Club Scout Clamping Unit with the upper V block removed. The torque screw clamped down on the center of the chuck. It held it very nicely. I had built a small 50-gram tip weight to attach to butt. I guess most people use a split grip as a butt weight. This seemed a bit crude so I build a tip weight by drilling a 5/8" hole in a piece of 1" hex stock and putting a set screw in it. At 50 grams the weight is only about an inch long. For consistency sake I attached it to the butt at 45". With this setup I could get both a butt and tip frequency reading a matter of seconds.
I didn't really know what to do with the data I generated on all these shafts. I decided to ratio the tip and butt frequencies and see what I got. The SK definitely had a lower ratio than the Aldila indicating it was a tip weak shaft. At least it's tip weak when it's untrimmed. The Aldila had a ratio of 1.00. The highest ratio shaft award went to the UST Pro Force at 1.016. I guess that shouldn't be a surprise. I only used this shaft a couple of times but it always seemed to me to be stiffer than board even though I thought I had the frequency (butt) just right.
| Shaft | Butt Freq. | Tip Freq. | Ratio |
| SK Tour Trac 100 S |
269 |
222 |
0.825 |
|
TT Dynamic Gold X100 X |
257 |
220 |
0.856 |
|
TT Dynamic Gold S300 S |
252 |
216 |
0.857 |
|
TT Lite R/S |
234 |
203 |
0.868 |
|
Graman 540 S |
261 |
230 |
0.881 |
|
SK Tour Trac 80 A |
242 |
216 |
0.893 |
|
SK Tour Trac 90 R |
255 |
228 |
0.894 |
|
Graman 440 S |
267 |
239 |
0.895 |
|
SK Tour Trac 80 R |
252 |
228 |
0.905 |
|
TT Dynamic Gold R300 |
236 |
214 |
0.907 |
|
Graman 540 X |
265 |
243 |
0.917 |
|
Graman 340 R |
243 |
224 |
0.922 |
|
Graman 340 S |
255 |
236 |
0.935 |
|
SK Pure Energy R |
250 |
232 |
0.928 |
|
Dynamic Lite R/S |
242 |
225 |
0.930 |
|
Graman 540 R |
240 |
226 |
0.942 |
|
Graman 440 R |
247 |
234 |
0.947 |
|
SK VIP L |
222 |
219 |
0.986 |
|
Graman 340 A |
226 |
224 |
0.991 |
|
UST Pro Force 65 S |
265 |
265 |
1.000 |
|
Aldila Longwood 50/50 X |
280 |
280 |
1.000 |
|
UST Pro Force 65 R |
251 |
255 |
1.016 |
What do these ratios mean to the clubmaker? I'm not sure but maybe the cpm you've chosen for a customer might be adjusted slightly depending on the brand of shaft you plan to use and its tip/butt ratio. At any rate I thought the technique to generate these ratios was pretty neat. I'd be curious what you folks think about this subject.
Some time after running these tests it occurred to me there is a problem with the data. You'll note in the table that the steel shafts appear to be rather tip weak. This is probably not the case. If you go back to Tech Note 1 you'll see the frequency is inversely proportional to the "effective" weight on the end of the shaft. Effective weight is the sum of the tip weight as well as a portion of the weight of the shaft itself. With only a 50 gram weight on the butt end of the shaft the weight of the shaft becomes very significant. The problem gets even worse. When you realize the shaft is being clamped at the tip the major weight of the shaft is out in the vicinity of the butt itself. For more on this subject see Tech Note 36 on Zone Measurements.