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big k
Guest
I didn't want to hijack the other thread but attached is some information that I put to gather on the physics in involved. please feel free to comment good or bad see the PDF attachment
Big k
Big k
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pacecil
Guest
You used a lot of scientific and engineering terms, but that's all you have done...use the words! You really haven't said anything that has any meaning as far as vibration or tuning - or guns for that matter! Sorry to come down on you so hard but you did say "good or bad".
rifleing turns ratio (a very important number!)
resonance (nice scientific word!)
power in synchronizition (???)
sine wave ( a plot or a barrel shape???)
peak vs null (new definition of sine wave???)
knowing the wave length (right!)
laser just touching the barrel (wow, engineers could really use that concept!}
metric conversion (thats real science!)
strange gage (those are best kind to use!)
barrel tuning physics (that's a catchy title!)
rifleing turns ratio (a very important number!)
resonance (nice scientific word!)
power in synchronizition (???)
sine wave ( a plot or a barrel shape???)
peak vs null (new definition of sine wave???)
knowing the wave length (right!)
laser just touching the barrel (wow, engineers could really use that concept!}
metric conversion (thats real science!)
strange gage (those are best kind to use!)
barrel tuning physics (that's a catchy title!)
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Larry Elliott
Guest
Gotta agree with Pacecil. All the explanations or mathematics in the world don't prove anything unless they can be applied to the problem at hand by someone shooting the rifle.
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pacecil
Guest
No, Larry you missed my point. Explanations and mathematics DO mean a lot. The point was; big k didn't make any real explanations, or use any mathematics, he just used a lot of "wannabe-engineer" words! Just like a whole bunch of other guys posting in this forum!
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Larry Elliott
Guest
I just glanced at the pdf, but the explanations offered didn't say anything. I've read a lot of articles where the author lays out pages and pages of calculations and formulae along with explanations. Unfortunately unless the reader is capable of applying them to the problem at hand in the field or on the range they don't do much good.
Most shooting problems aren't like building a bridge or some other structure since they contain so many unknowns. From my limited understanding of tuners they need to be adjusted "on the run" from time to time, and I can't see how that problem could be solved without plain old experience and experimentation.
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big k
Guest
Ouch you guys are tough, maybe I can answer some of your questions.
What I was trying to do was to approach the barrel tuning from a different approach and get a discussion on the subject. I guess I could have gone into a lot of formulas but I don't think that is necessary to under stand the basic idea. I find that most barrel tunning is by trial and error . What I want to get across is a way to get closer to the optimum point easily.
One of my mistakes was to assume that every body understood what resonance was and that mechanical oscillations takes on the form of a of a sign wave or is sinusoidal
Also I did not mean to imply that it was not necessary to for some one to fire the rifle.
Only to help explain what was happening to the barrel and a alternate way of seeing it. Using a different methods
I don't mind any criticism as long as you have a definite point, that that helps correct errors or helps define and educate the reader
I think personal attacks accomplish nothing and add no usefully information
Pacecil your first reply although some what sarcastic, did have usefully comments and questions so I have tried to clarify some of them.
eA sinusoidal wave or function, that is, one moving in SIMPLE HARMONIC MOTION according to the function
A sin (2pft)
where A is the AMPLITUDE of the wave, f its FREQUENCY, and t is time.
According to the FOURIER THEOREM, any periodic WAVEFORM may be analyzed as the sum of a series of sine waves with frequencies in a HARMONIC SERIES, each of which has an amplitude and phase angle given by the Fourier coefficients. Since a sine wave has only a single frequency associated with it, it may be considered the simplest sound.
See: FOURIER ANALYSIS, FOURIER SYNTHESIS, GRANULAR SYNTHESIS, LAW OF SUPERPOSITION, SIMPLE TONE, SINE TONE, SOUND SYNTHESIS.
s a goo sed to model many periodic and vibrational patterns in nature.
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Here is a sight with a good description http://www.ask.com/bar?q=frequency&page=1&qsrc=2105&ab=6&u=http://id.mind.net/~zon
Resonance and Energy Transfer
Resonance can be defined as the condition in which force is applied to an oscillator at the point of maximum amplitude. In this way, the motion of the outside force is perfectly matched to that of the oscillator, making possible a transfer of energy.
As its name suggests, resonance is a matter of one object or force "getting in tune with" another object. One literal example of this involves shattering a wine glass by hitting a musical note that is on the same frequency as the natural frequency of the glass. (Natural frequency depends on the size, shape, and composition of the object in question.) Because the frequencies resonate, or are in sync with one another, maximum energy transfer is possible.
The same can be true of soldiers walking across a bridge, or of winds striking the bridge at a resonant frequency—that is, a frequency that matches that of the bridge. In such situations, a large structure may collapse under a force that would not normally destroy it, but the effects of resonance are not always so dramatic.
I had used the example of the power lines and how they used the orange balls to stop the wires from reaching resonance. This is basically what you are doing with a barrel bedding or a tuner which gives much finer adjustment. By knowing the wave length of the barrel you can locate the optimum point to locate the tuner. Then by using one of the system that I showed while firing the gun you can determine where on the sign wave the bullet is leaving the barrel. The object is to find for any one load what the optimum position for the tuning is for that load. As I was trying to say the best place to try to adjust the tuning whether by tuner or load adjustment is at either maximum amplitude points on the curve as this will give you the broadest range and the minimum changes for any small variations in other parameters.
By knowing what the wave length of the barrel resonance is you can measure from the fixed point at the junction of the barrel and the receiver then buy bedding binding or weighting a point 1/3 the length back down the barrel to keep the barrel from going into resonance. This minimizes the amplitude of the oscillation by monitoring the the point on the curve with the equipment shown you can then adjust the tuning for minimum movement of the barrel as the bullet leaves the barrel the best place for the most consistency would be as the wave reaches its peak
If you would like to see and read about
strain gage's
http://www.intellivibestore.com/main.sc
http://www.ask.com/bar?q=Strain+Gauges+Applications&page=1&qsrc=6&ab=1&u=http://www.s
Small inexpensive lasers
http://www.ask.com/bar?q=frequency&page=1&qsrc=2105&ab=6&u=http://id.mind.net/~zon
inexpensive photo sensors
http://web4.automationdirect.com/ad...electric_Sensors?bizcom-photoelectric-sensors
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Vibe
Guest
Discuss it with Bill Calfee and get back with us on what you find out. 
Somehow I feel plagiarized.
Somehow I feel plagiarized.
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Louis Boyd
Guest
I'm surprised no one here seems to have noticed that the equation near the beginning of the PDF:
wavelength (meters) = 300/frequency in megahertz
gives the approximate wavelength for electromagnetic energy propagating in a vacuum. That has little or nothing to do with the mechanical vibrations of a rifle barrel. A steel bar (barrel) has many resonant frequencies each depending on what location and direction forces are applied. Abarrel can vibrate at multiple frequencies simultaniously. The wavelength of mechanical vibrations propagating through a solid are not defined by it's frequency unless the mode of propagation is also defined. Possible modes include lognitudinal, tortional, and flexure though all are related. A barrel being attached to a mass (like a receiver and a stock) or perhaps a "barrel tuner" has major efffects on the possible modes of vibration, their frequencies, and their dampening rates.
Big K, Not to dampen your enthusiasm, but I'd suggest you set up and observer the results of some of your ideas with actual experiments before publishing them. You've bitting off a complex subject and (in my opinion) have several misconceptions. I'm not an expert on rifle tuning. I build astronomical telescopes. How they flex and vibrate from changing their pointing and from wind is of concern for me. The principles are similar.
wavelength (meters) = 300/frequency in megahertz
gives the approximate wavelength for electromagnetic energy propagating in a vacuum. That has little or nothing to do with the mechanical vibrations of a rifle barrel. A steel bar (barrel) has many resonant frequencies each depending on what location and direction forces are applied. Abarrel can vibrate at multiple frequencies simultaniously. The wavelength of mechanical vibrations propagating through a solid are not defined by it's frequency unless the mode of propagation is also defined. Possible modes include lognitudinal, tortional, and flexure though all are related. A barrel being attached to a mass (like a receiver and a stock) or perhaps a "barrel tuner" has major efffects on the possible modes of vibration, their frequencies, and their dampening rates.
Big K, Not to dampen your enthusiasm, but I'd suggest you set up and observer the results of some of your ideas with actual experiments before publishing them. You've bitting off a complex subject and (in my opinion) have several misconceptions. I'm not an expert on rifle tuning. I build astronomical telescopes. How they flex and vibrate from changing their pointing and from wind is of concern for me. The principles are similar.
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big k
Guest
I appreciate your input that is the type of discussion I had hoped for I am only trying to reach out of the box and hoping that through discussions to get other people to think and maybe come up with new ideas to try
I have run testing on relatively large radio telescopes for resonance a 9m antenna will have a resonate frequency of above 3 Hz depending on the weight of the moving reflector and is very scary when you passing through resonance.
Yes you are correct that solids do have a wavelength different due to propagation through a solid, depending on the material and when vibrated at resonance there are modes or harmonics that contribute to the amplitude as they synchronize with the main mode.
The idea as I stated is to avoid getting close to resonance that is why I said to place the bedding 1/3 of the distance from the end of the barrel this has a dampening effect and minimizes the harmonics.
I used formula for free space because it is a constant propagation, unlike a solid as they would differ with different materials, using the formula will get the tuner close, if you use one.
Then by using either system and monitoring the amplitude of the oscillations at the end of the barrel. Relocate the body of the tuner to further decrease the amplitude.
This is not a cure all but is a way to minimize the effects of barrel oscillation contribution and to see if other changes make improvements or allow a definite way to tell which direction to go for improvement,.
Boyd Allen
Active member
....and then we have to fly the plane to see if the assumptions that were made when it was designed are correct.
Has your analysis of this particular problem led to any novel solutions that produce superior results? It would be fun to read of something new.
One more question, just how is free floating a barrel a form of damping? I would think that free floating is a way to eliminate the variables introduced by most damping schemes.
Has your analysis of this particular problem led to any novel solutions that produce superior results? It would be fun to read of something new.
One more question, just how is free floating a barrel a form of damping? I would think that free floating is a way to eliminate the variables introduced by most damping schemes.
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pacecil
Guest
O boy!...
Another thread on barrel vibration! Here we go again talking about what happens AFTER the bullet has left the barrel. I suppose it does help confirm what we learned in physics. You can however forget about all that horrible resonance - it ain't happening after the bullet is gone!
And then there's that Calfee test where we hang a barrel up without receiver or stock and watch how it vibrates. Again that's pretty interesting when you want to confirm what you thought you knew about natural vibrating bars. (no resonance here either unless you get careless with your striker!)
And by God we are even back with "flat sine waves"! I'm sure it won't be very long until here comes "stopped barrels". And then will come secret formulas for learning where to cut the barrel and how much weight to hang back on it!
If it weren't for the arguments, and name calling, and insults, and crazy ideas, and wild claims, this just wouldn't be any fun at all! If Calfee gets on here it will really be a ball! I'm kinda looking forward to it!!!
Another thread on barrel vibration! Here we go again talking about what happens AFTER the bullet has left the barrel. I suppose it does help confirm what we learned in physics. You can however forget about all that horrible resonance - it ain't happening after the bullet is gone!
And then there's that Calfee test where we hang a barrel up without receiver or stock and watch how it vibrates. Again that's pretty interesting when you want to confirm what you thought you knew about natural vibrating bars. (no resonance here either unless you get careless with your striker!)
And by God we are even back with "flat sine waves"! I'm sure it won't be very long until here comes "stopped barrels". And then will come secret formulas for learning where to cut the barrel and how much weight to hang back on it!
If it weren't for the arguments, and name calling, and insults, and crazy ideas, and wild claims, this just wouldn't be any fun at all! If Calfee gets on here it will really be a ball! I'm kinda looking forward to it!!!
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big k
Guest
Boyd, to answer your question about free floating the barrel
If the natural oscillations of the free floating barrel are such that the peak amplitude is reached at the end of the barrel you are already at the optimum point on the curve. Bedding the barrel would not improve the accuracy and could degrade it. I will try to explain. In the two plots (see the attachment) were the phasing is equal so that both peaks occur at the end of the barrel at the time the bullet leaves.
The un-bedded barrel has a longer wave length then the bedded one so the period across the peak although of greater amplitude has a minimum amplitude change over a greater time period during the cycle, as compared to the bedded barrel. Therefore less over all sensitivity to changes. Such load and temperature variations etc.
Boyd Allen
Active member
You mean to say that for a given system and energy input, the RMS value remains the same and since bedding the barrel shortens its vibrating length, which raises its frequency, in order for the RMS value to remain constant the amplitude of the wave must increase.....unless some of the energy is transferred to the bedding system, and converted to heat? Isn't this transfer and conversion what constitutes damping?
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pacecil
Guest
To big k
Why do you want to discuss or describe the natural vibration that occurs after the bullet has left the barrel? The forced vibration occurring while the bullet is in barrel, as a result of recoil and bullet inertia, may or may not be in form of sine wave.
Why do you want to discuss or describe the natural vibration that occurs after the bullet has left the barrel? The forced vibration occurring while the bullet is in barrel, as a result of recoil and bullet inertia, may or may not be in form of sine wave.
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big k
Guest
you are correct when you say that when you bed the barrel the frequency increases is due to shortening the effective length of the barrel, also the energy in the wave, due to its being transferred to the bedding, decreases.
the Ideal, in either case ,as long as the projectile leaves the barrel at the peak of the cycle you will have basically have equal accuracy with either system and the absolute amplitude of either one has no effect, as long as it is constant.
That being said The difference with the free floating barrel is that because the the length of the barrel is longer, the frequency will lower.
This causes the curve of the cycle at the peaks to be of longer duration, with a smaller change in amplitude over a longer period.
Since the wave is actually movement the of the barrel, the movement over time is less then the dampened barrel which has a higher frequency rolls off quicker.
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the floating barrel is less sensitive to miner changes in other parameter changes, such as load variations. barrel temp etc.
The main thing is to be able to tune the barrel with tuner, bedding or load etc,
so that in either case it leaves the barrel at the same place with each shot.
The best place that allows the least sensitivity to variations of parameters is at the peaks of the wave because the barrel is moving at its slowest and with the smallest change in the amplitude over a longer period. I would actually be stopped at the absolute peak
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pacecil
Guest
To big k
I suggest you take a look at varmintal.com
I suggest you take a look at varmintal.com
Boyd Allen
Active member
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big k
Guest
Very interesting article thank you for sharing it. Very informative.
When I started this thread I was looking for an inexpensive and portable way to see the effects of the
of barrel oscillations weather natural or other wise ( as pointed out in the article) and how to use that data to improve accuracy. I must admit I did not think that the pressure wave would over ride the natural frequency response of the barrel The data also shows that the effects cause movement are mainly in the vertical axis, And are sinusoidal.
Although there are multiple sub mode harmonics they are of insufficient energy to greatly effect the main mode. The charts also show that as the projectile leaves the end of the barrel closest to the peak of the pressure wave the accuracy improves as I had stated in my analysis due to decrease in vertical movement over time.
I will also be looking at using along with the strain gauge, and laser system for measuring the barrel movement I am going to see if I can find a accelerometer, that is cheep enough and light enough to mount on the barrel.
Thank you all for contributing to the information and for your questions