Shaft frequency
- Thread starter conetip
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Neil,
I was told many years ago that cues vibrate at a frequency of approx. 40Hz. I say approx. because there are many variables to be considered.
I don't know that any of the aftermarket shafts will vary too much from that figure. As you know, that's the low-end frequency of a pretty good bass speaker/woofer.
FWIW, you want to be careful about 'tapping a cue sideways'. They're not intended to experience that type of hit and bad things can happen.
I was told many years ago that cues vibrate at a frequency of approx. 40Hz. I say approx. because there are many variables to be considered.
I don't know that any of the aftermarket shafts will vary too much from that figure. As you know, that's the low-end frequency of a pretty good bass speaker/woofer.
FWIW, you want to be careful about 'tapping a cue sideways'. They're not intended to experience that type of hit and bad things can happen.
I'm afraid each individual shaft (even if they are all the same type) will be slightly different. Also the resonant frequency of a shaft will be different to the frequency of a whole cue, due to more mass and volume.
Another thing to consider is that, like with musical instruments, the full resonant spectrum will be composed of not only the fundamental but of many harmonics which, sometimes, are even more audible than the fundamental. You wont hear 40Hz, just feel it in your hand but you will hear the upper harmonics quite well. The harmonics will also depend somewhat on where you strike the shaft "sideways".
Ok... I shut up. :boring2:
Another thing to consider is that, like with musical instruments, the full resonant spectrum will be composed of not only the fundamental but of many harmonics which, sometimes, are even more audible than the fundamental. You wont hear 40Hz, just feel it in your hand but you will hear the upper harmonics quite well. The harmonics will also depend somewhat on where you strike the shaft "sideways".
Ok... I shut up. :boring2:
I'm afraid each individual shaft (even if they are all the same type) will be slightly different. Also the resonant frequency of a shaft will be different to the frequency of a whole cue, due to more mass and volume.
Another thing to consider is that, like with musical instruments, the full resonant spectrum will be composed of not only the fundamental but of many harmonics which, sometimes, are even more audible than the fundamental. You wont hear 40Hz, just feel it in your hand but you will hear the upper harmonics quite well. The harmonics will also depend somewhat on where you strike the shaft "sideways".
Ok... I shut up. :boring2:
In this case the fundamental frequency of oscillation is directly related to the stiffness of the shaft. I don't believe that this is about the tonal qualities of a shaft, just it's stiffness. Here is a device to measure the fundamental frequency of golf shafts, a common way to accurately measure dynamic stiffness :
http://www.golfsmith.com/products/236821/Golfsmith/Professional_Frequency_Analyzer
I see that this unit measures up to 1000 cpm , which is only 17 hz. Rarely do golf shafts measure over about 500 cpm (8 hz) and I would expect that pool cue shafts are much stiffer, so KJs 40 hz number may be reasonable based on my the gut-feel, but measuring might be interesting.
It this something that cuemakers might like to measure ?
Dave
A golf shaft may well be quite low due to the mass of the club or head. Pool cues do not have a head or an added pendulum.But holding the tip end and vibrating the handle is just asking for trouble.
It seems that the shaft will vibrate at the same rate but to different amplitude with different handles and where it is being held on that handle.
I am going to put together something to measure the frequency of my shafts and see what numbers come out.
Neil
It seems that the shaft will vibrate at the same rate but to different amplitude with different handles and where it is being held on that handle.
I am going to put together something to measure the frequency of my shafts and see what numbers come out.
Neil
i am pretty sure that they frequency test them prior to installation also.i have bought shafts that are stamped with the frequency that were brand new and uninstalled,the last one being 278cpm and it is very stiff.they also frequency match irons shafts for the pros prior to installation.
40 hz = 40 cps = 2400 cpm
"Maple 10x stiffer than steel" does not account for anywhere near all the variables. The tube / shaft configuration influences stiffness, as does the end-weight as previously mentioned. Also the longer the tube the lower the frequency, and a golf shaft is monger than a pool cue shaft. A 10" maple dowel will measure much stiffer than a 48" long steel tube. I'd agree that if one measured identical cylinders of maple and steel the steel would be stiffer, which may be what's influencing your thinking.
They do test shafts 'raw', but you add a tip weight for measurement purposes. Without the tip weight the frequency would be much higher, but again, nobody measures then that way. The <500cpm number for golf shafts is measured with a tip weight.
Dave
steel shafts for say a pitching wedges is about 34" and a maple shaft is about 30" so i still don't see why there is such a large disparity.i also realize the steel is tube and the Maple is solid but the steel still feels pretty stiff.
just trying to learn.
just trying to learn.
I think that, although the resonant frequency might be related to the stiffness of the shaft, it is not the only factor to be considered. Tension, length and mass among others affect the resonant frequency of each object. I would say comparing a steel shaft with a maple shaft is like comparing apples to oranges due to the different constants involved.
Also, resonance theory is usually based on a perfect cylinder or tube, I would guess that the fact that a maple shaft is tapered would affect somewhat too.
http://en.wikipedia.org/wiki/Mechanical_resonance
http://en.wikipedia.org/wiki/Acoustic_resonance
Of course I could be completely wrong
. Maybe Dr. Dave could provide some insight... I am not a physicist by any means. :embarrassed2:
If the idea is matching shafts for flexibility why not measure flex at a specific hung weight from the tip? or maybe even graph the results for several increasing weights? I think that us, pool players, would still find differences in two shafts that are the exact same weight, same taper, same flex pattern and same acoustical resonant spectrum; but then grab our opponent's cue by mistake and play with it for several shots without noticing
Also, resonance theory is usually based on a perfect cylinder or tube, I would guess that the fact that a maple shaft is tapered would affect somewhat too.
http://en.wikipedia.org/wiki/Mechanical_resonance
http://en.wikipedia.org/wiki/Acoustic_resonance
Of course I could be completely wrong
. Maybe Dr. Dave could provide some insight... I am not a physicist by any means. :embarrassed2:If the idea is matching shafts for flexibility why not measure flex at a specific hung weight from the tip? or maybe even graph the results for several increasing weights? I think that us, pool players, would still find differences in two shafts that are the exact same weight, same taper, same flex pattern and same acoustical resonant spectrum; but then grab our opponent's cue by mistake and play with it for several shots without noticing
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perspicaz you have mentioned some good points and references.
I have my own handles with cork in the middle section. These handles dampen the vibration from the cue very quickly, while a traditionaly made wood handle,does not dampen the vibration as quickly.
With some high speed photography, it has shown that there seems to be a small advantage with a handle that dampens the vibration while maintaining the frequency of the shaft, particuarly when hitting in the extreme english position.
When weights were used to measure the deflection of the shaft and then try to get a relationship to the deflection from the weights and then compare the playability, it was very difficult. Especially comparing a carbon shaft to a wood shaft.
There seems to be about 5 hz difference between a shaft that is very stiff hitting and a 10 inch pivot point , to a good hitting shaft with a 11.5inch pivot point.
Neil
I have my own handles with cork in the middle section. These handles dampen the vibration from the cue very quickly, while a traditionaly made wood handle,does not dampen the vibration as quickly.
With some high speed photography, it has shown that there seems to be a small advantage with a handle that dampens the vibration while maintaining the frequency of the shaft, particuarly when hitting in the extreme english position.
When weights were used to measure the deflection of the shaft and then try to get a relationship to the deflection from the weights and then compare the playability, it was very difficult. Especially comparing a carbon shaft to a wood shaft.
There seems to be about 5 hz difference between a shaft that is very stiff hitting and a 10 inch pivot point , to a good hitting shaft with a 11.5inch pivot point.
Neil
Normally a set of shafts is frequency matched with the shafts measured at their full raw length. Once tip-trimmed and cut to length a pitching wedge shaft is WAY stiffer than a 1 iron shaft as your gut feel suggests.
If you want a fairly simple test try using a static bending board style of measurement :
http://www.golfworks.com/product.asp?pn=GSDB&bhcd2=1248309381
This should give you an idea as to how they work .... a handy dude like yourself could rig one up in a heartbeat imo.
Take a raw golf shaft (cheapest way to get one might be to buy an old used driver for a few bucks and cut out the shaft) and a pool cue shaft and hang 'em on the board.
Dave
I think the situation with the butt end of the cue that is corked and maybe one with a pie shaped core or laminated core would be very interesting also. And even those vibration reduction type bumper kits that atlas sells!!! From talking to some cuemakers who are really into this frequency stuff I believe all of the above need to be considered. Just a thought.
Talked to my former boss and good friend this weekend about where he gets his shaft stash from. He goes out in person and picks them out. I'm talking some serious driving time here. He also said he has a cue making buddy that drops every shaft blank lightly on a cement floor and can tell by the sound if the shaft is worthy of being on one of his cues. I thought it was some pretty good info....