The Parallel Node, Calfee

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Kathy

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My friends:

A bit of news: Over the last several days I have been working with Roger von Aherns.

Roger is producing a set of muzzle device weights for the Hoehn/Harrell style muzzle device (tuner)....and has advertized them here on Benchrest Central.

If the world don't end first, in a few days, Roger, and I, will we testing a new muzzle device design.......this is Roger's baby.....he will give the details as they warrent......(this new muzzle device may prove worthless, or it may turn out to be pretty neat.....time will tell)

The parallel node: The reason a muzzle device does improve accuracy is because of what I have labled the "parallel node", in the vibration pattern of a rifle barrel, when fired.

If there was no "parallel node", a muzzle device (tuner) would have no, or very little affect, on accuracy.

A question: Please someone help me here: If the dead spot, in the vibration pattern of a rifle barrel, when fired, was X shaped, and if that X shaped node could be moved to the crown, with a muzzle device ( tuner), how would that improve accuracy?

My engineering friends....how could an X shaped node (dead spot) that was moved to the exit of the crown, improve accuracy?

My dear friends, this new muzzle device that Roger is developing may turn out to be something that is not workable......if the world don't end...we will know something in a few days....

Now, you engineering friends??

Your friend, Bill Calfee
 
Words have meaning.

Bill:
The basis of written and oral communication is that words have meaning. If you can clearly define the words "parallel node", then please do so. I have been unable to find these terms used outside of some computer network websites, which are unrelated to the discussion of waves or rifles.

The barrel tuners currently in use and currently in development have a strong following and presumably work well. However, the apparent fact that tuners aid in shooting better groups does not prove the existence of a "parallel node".

Without defining the terms you use, people's perception of what you say is that of a snake oil salesman.

SteveM.
 
Thanks for the link Fred.

Fred:
Thanks for the link. Yes, I have read the article and looked at the illustrations provided by Bill Calfee before. By most accounts, the tuners actually work. What doesn't seem to work, however, is the explanation of why the tuners work.

I'd like to see a substantially better explanation than what Bill has posted above:

"The parallel node: The reason a muzzle device does improve accuracy is because of what I have labled the "parallel node", in the vibration pattern of a rifle barrel, when fired."

I have no problem with somebody promoting or selling any product which can improve accuracy. The thing I have a hard time accepting is the sort of psuedo-scientific explanations which have been offered so far.

Can anyone find an explanation of a "parallel node" outside of this forum (or a related forum) which is applicable to vibrations or waves in steel structures (rifle barrels in particular)? If so, please post a link so that we can all have the same understanding.

SteveM.
 
The explanations of "how and why it works" .... of which there are many, tends to be the "hard" part .... I have my own beliefs, as do most .... bottom line, as long as it works.

Fred :)
 
Kathy said:
My friends:

A question: Please someone help me here: If the dead spot, in the vibration pattern of a rifle barrel, when fired, was X shaped, and if that X shaped node could be moved to the crown, with a muzzle device ( tuner), how would that improve accuracy?

My engineering friends....how could an X shaped node (dead spot) that was moved to the exit of the crown, improve accuracy?

My dear friends, this new muzzle device that Roger is developing may turn out to be something that is not workable......if the world don't end...we will know something in a few days....

Now, you engineering friends??

Your friend, Bill Calfee
Click to expand...
Why ask a question that has been thoroughly answered so many times? Varmint Al did an excellent FEA study and animation on the subject, several others have done the math - 3 Rivers Technical even went so far as to calculate the further machining needed to change the barrel properties to approximate a "parallel node" of sorts (since it cannot happen in a "standard" bar or straight barrel shape).

Tuners modify the reaction time of the barrel to the point where faster bullets exit while the barrel muzzle is pointing slightly lower than when the slower bullets do, which allows the slower bullet to drop into the same POI as the faster bullets - the better tuners do this for the widest possible set of velocities, thus covering the expected ES of the various loads expected to be encountered.

The added mass of the tuner also reduces the overall reaction speed of the muzzle, which also allows for the reduction in any side to side component of the vibration pattern.

Now all of this can also be accomplished with the node not at the muzzle, however, in that position there is some transverse motion remaining, and as the bullet exits, this remaining motion can result in imparted yaw - which is not real good for accuracy. Keeping the node at the muzzle really only reduces the possible causes of imparted yaw to a minimum.

If there were indeed a true "parallel node" there would be no mechanism to compensate for the ES of the various loads.
 
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Vibe said:
Tuners modify the reaction time of the barrel to the point where faster bullets exit while the barrel muzzle is pointing slightly lower than when the slower bullets do, which allows the slower bullet to drop into the same POI as the faster bullets - the better tuners do this for the widest possible set of velocities, thus covering the expected ES of the various loads expected to be encountered.

.
Click to expand...


Two years of reading about nodes, parallel and otherwise, somebody finally put it in terms I can get! Thanks Vibe. All that scientific stuff may be well and good, but, what some of us need is basic language. It's nice to know why something works. On the other hand, if it works why fight it, use it and be happy. Don't have the slightest idea how you can transmit moving pictures thru the air either, doen't mean I don't like to watch TV though.

Ken
 
Well said Ken.

I think too many rocket scientists are here at BRC. :D

Seems to me everyone always trys to doubt Bill Calfee just because he's Bill Calfee. How many rimfires are those doubters building that are winning or breaking world records? The facts are that very few benchrest rimfire barrels are winning without a tuner on the end of them. There is a reason for that. Why is that? Because they work. ;)
 
My engineer friends

My engineer friends:

Would any of you care to answer the question I asked when I started this thread? I quote myself:

"A question: Please someone help me here: If the dead spot, in the vibration pattern of a rifle barrel, when fired, was X shaped, and if that X shaped node could be moved to the crown, with a muzzle device ( tuner), how would that improve accuracy?"

Your friend, Bill Calfee
 
To Bill, here's your "engineering" answer....

A question: Please someone help me here: If the dead spot, in the vibration pattern of a rifle barrel, when fired, was X shaped, and if that X shaped node could be moved to the crown, with a muzzle device ( tuner), how would that improve accuracy?
My engineering friends....how could an X shaped node (dead spot) that was moved to the exit of the crown, improve accuracy?

It wouldn't, unless at the same time the node were moved, the amplitude (height) of the wave were reduced. Adding weight to the end of a vibrating bar should reduce the amplitude and also move the node. The only point at which the wave is parallel to the axis is at the antinode. If added weight moved this closer to the muzzle then this would also affect accuracy.

What you have shown as a "parallel node" in your PS article could only be achieved by placing a rigid support at that point on the barrel. (Some physics books show just such a support when they explain how vibration occurs in bars.) Some testers have also done this but there was no improvement in accuracy. I assume this was because you can't achieve a truly rigid support except in theory.

Re visiting another topic, that is "stopped motion". The antinode is at zero velocity so I guess you could call this point as "stopped". This is a point of zero velocity but at maximum acceleration. Your description of what occurs in a barrel may be valid if you are talking about the "parallel", "stopped" antinode. However, and this is an important point: all this discussion applies to NATURAL vibration. There is little indication the barrel is vibrating this way as the bullet leaves the muzzle!
 
Same here.

"I don't doubt Bill Calfee the rifle builder at all. It's Bill Calfee the physicist I have questions about."

Same sentiment here. If Bill Calfee wants to sell rifles, tuners, whatever, more power to him. It's when he starts posts like this one, claiming things like the existence of a "parallel node" that people start getting suspicious about the how's and why's of Bill's explanations.

Please remember, Bill started this thread and still hasn't been able to define the words that are so important to his explanation of why his tuners work.

SteveM.
 
Friend pacecil

Friend pacecil:

Looks like we was posting at exactly the same time.....

I thank you for your answer which I quote from.....2nd paragraph:

"It wouldn't"

MY friend, you are absolutely correct: If the node were X shaped, there would be absolutely no increase in accuracy.

A muzzle device increases accuracy by moving the "parallel node" in the vibration pattern of a rifle barrel, when fired, to the exit of the crown.

This subject could be argued forever, but the reason a muzzle device improves accuracy is exactly as I have stated.

Why is it important that folks understand how a muzzle device improves accuracy? It's important so folks can realize the "full potential" that a muzzle device offers, toward improving accuracy.

Thanks again my friend for your answer.

Your friend, Bill Calfee
 
This is some funny stuff....

Absolutely hilarious quote right from the horse's mouth....

"This subject could be argued forever, but the reason a muzzle device improves accuracy is exactly as I have stated."

Bill, you can't even define what the "parallel node" is, and you expect people to accept a statement like the one you just posted. LOL. (laughing out loud).

Absolutely priceless and hilarious at the same time.

SteveM.
 
Reflecting back on my college physics from many many years ago, this is what I remember about sine wave, or acoustic wave theory and I believe what Bill is calling the "parallel node" is what I remember calling the "null" point. "A null point, in acoustics and signal processing, refers to the point on a sound wave, at which there is zero displacement of the medium. This is also called a node."
 
Friend Bill,

If I may .... I have a question for you ....

I have taken this from the PS Good Vibrations Article ...

"So when a rifle barrel vibrates, the node, or dead spot, consists of a little section of the barrel that is perfectly parallel. A barrel tuner causes this little parallel barrel section to be moved to the exact crown of the barrel. So the fact that the barrel, right behind the node, or dead spot, is vibrating, the angle of approach to the node has no effect on accuracy. The bullet is always exiting that little parallel section of the barrel, which is perfectly stationary, which is caused to be at the exact crown of the barrel by the actions of the barrel tuner. It’s awesome!"

If I have this right .... we want that "little section of the barrel that is perfectly parallel." at the muzzle end of the barrel ... so that the exiting bullet will always be leaving in a straight line .... this is what you called stopped.

Am I correct ....

Thank you for your time ... Mike
 
Kathy said:
My engineer friends:

Would any of you care to answer the question I asked when I started this thread? I quote myself:

"A question: Please someone help me here: If the dead spot, in the vibration pattern of a rifle barrel, when fired, was X shaped, and if that X shaped node could be moved to the crown, with a muzzle device ( tuner), how would that improve accuracy?"

Your friend, Bill Calfee
Click to expand...
What good would it do. You've got your mind made up, has been for years.

I've explained why it has to be an "X" shape, both in terms of accurarcy and it's been demonstrated in terms of physics in the FEA animation. (of course the "X" is only apparent when you superimpose the wave form at two distinct points in time, only one of which is pertinent to the discussion) And I've pointed out why it cannot be a straight "parallel" section in the midst of an otherwise smooth curve. Both in terms of accuracy and in terms of physics. If it was a straight section there could be no compensation for velocity ES, and we both know that that is one of the prime advantages of a tuner.

I do have an engineering degree, since 1985, and have used it in dabbling a bit in vibration applications, though most of my professional efforts were put to prototype manufacturing machine design. For 10 years before that I was worked my way through school as a machine design drafter. I also attempted to use that knowledge to help you clarify what you were attempting to explain, to apparently no avail.

I personally am finding your lack of response to any form of proven facts, and accepted scientific theory, as just a bit insulting. Not to mention just a bit arrogant, considering that your published "theory" is just blatantly wrong. Particularly when the actual behavior of a vibration pattern in a cantilever beam comes so much closer to describing what you have been achieving.

I'm done. I can only beat my head against the brick wall for just so long. I have other issues I can devote the attention to that have at least some chance of being productive. So much for wanting to "help". Good luck.

David Epperson
AKA Vibe
related project 22 Epperson Cricket
 
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Vibe
Thank you for the effort/facts you have put forth in your post. I follow your deductions and agree.
Fred K
 
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