The Parallel Node, Calfee

[Vibe]

I would bet that if you got Bill, Vibe, Lynn, Dave, JetMugg and the others sitting around a table, snacking on (Lord help us) head cheese and beer, this would be one heck of a lively conversation.

Let's just hope that it was after a good round of targets got punched in some favorable conditions.
Bill would have of course kicked our butts, I might end up ahead of Lynn (just because of the close range to the target ), but I'm not sure how I would do against JM. As for the head cheese, I'l try just about anything once (Heck I lived in New Orleans for 3 years - LOL)

 

[Fred J]

I'm Confused

I was always taught, that Parallel meant that the two lines never crossed.

Note, that A & B, are always parallel

 

[pacecil]

To all....

Bill Calfee has explained how he loves rifle accuracy and all things to do with guns. To him it is almost a religion - much like it is with many of us!

Have you ever tried to suggest to somebody, who feels very strongly about his religion, that his beliefs might be a little bit off based on scientific evidence??

 

[Vibe]

I was always taught, that Parallel meant that the two lines never crossed.

I would guess that the term "Co-incident node" just would not have had the same ring.

What am I doing?????????
I know what he meant (but that's still the problem).

 

[The Machine]

Could it be that the reason tuners work is a result of the placebo effect? Since noone seems to be able to give a definative explanation as to why they do, maybe, since those who purchase tuners in the first place tend to be people who believe in them or at least hope they work, could it be that it gives them a little added confidence for a more stable shot? And when they remove it from the barrel, they lose that extra confidence and go back to shooting wider groups? Just a thought!

Or maybe I"m just running out of ideas and want to contribute to a record length thread.

TM

 

[Bobby T.]

TM, it could be a little of both.

 

[Dave Shattuck]

Fred if you look at the rifles action as being 0 degrees there is a anti-node at 90 degrees that would be both parallel and perpindicular to the bore at that point.It doesn't seem to match up however to Bill Calfee's diagrams.
Lynn

Lynn,

Thank you! That helps explain it a little better, at least to me.

Let's look at what I am about to say with an open-mind remembering that none of it is being put into technical terminology.

Call it what you will, but the effect we are looking for from a tuner must be to move that "Anti-node", which is simultaneously both "Parallel", (as in Parallel Node) and "Perpindicular" with the bore out to the absolute point of exit from our muzzle, and the way we are trying to achieve this is by shifting the location of the center of our so called "Flat Spot" out to that point.

Would this make sense?

 

[Vibe]

both parallel and perpindicular to the bore at that point.

What???????

 

[bill s]

All wet?

I may be all wet and if I am, I'm sure I will hear about it.
But, is it possible to have more than one "wave" in a barrel at the same time?
And could the "tuner" line these 2 waves up to the muzzel? And could they then be in "parallel"? At the muzzel?
Here is what mean... One could be created from the firing pin strike and then one from the round going off(or down the barrel)
All this talk is about "one" wave....?????Could there be more????
What if you "ring" the barrel twice, real fast,do you still have only one "wave"???????? bill

 

[Kathy]

Friend Vibe

Friend Vibe:

It was kind of you to explain to me how to quote. Thank you......I still haven't figured it out yet as I want to quote from your #83 post, but don't know how to get back to it from here........

My friend, I am going to paraphraze from your #83 post, 2nd paragraph:

You ask; if there is a parallel node, why not take advantaage of its entire length instead of doing like I recommend, putting its exact center at the crown. Friend Vibe, that is an excellent question and it deserves an answer.

First, the parallel node's exact center never varies in distance to the crown.
As barrel vibrations increase, the parallel node shortens in length, and, vice versa, lengthens as vibrations slow down, ( different velocities of ammo).

If we set our muzzle device, in such a way, as to position the front edge of the parallel node at the crown, as you say, to take advantage of ALL of its length, to direct the bullet, should we then fire a round of higher velocity, the parallel node will shorten in length, exposing the "part cycle" to the exit of the crown. Of course accuracy suffers.

No my friend, the muzzle device need to be of a weight, and, of the proper position, in front of the corwn, to move the "exact center" of the parallel node to the exit of the crown. At this point, the muzzle is stopped, requiring no further adjustment of the muzzle device.

Thank you again my friend for the advice on quotes and for the excellent question.

Your friend, Bill Calfee

 

[Vibe]

Friend Vibe:

It was kind of you to explain to me how to quote. Thank you......I still haven't figured it out yet as I want to quote from your #83 post, but don't know how to get back to it from here........

You are of course welcome. My only purpose in posting in any of your threads has been to help. As for getting back to post #83..we can work on that as well
All post windows have the quote box in the lower corner, and clicking on that box will result in that post being quoted. As for moving back to a particular post - I supposed the simplest way is to click on the page number that contains that posting. The page number selection box is located at both the upper and lower right hand corners of the page being viewed. If you can read it you can quote it. Good luck.

My friend, I am going to paraphrase from your #83 post, 2nd paragraph:

You ask; if there is a parallel node, why not take advantage of its entire length instead of doing like I recommend, putting its exact center at the crown. Friend Vibe, that is an excellent question and it deserves an answer.

First, the parallel node's exact center never varies in distance to the crown.
As barrel vibrations increase, the parallel node shortens in length, and, vice versa, lengthens as vibrations slow down, ( different velocities of ammo).

From this statement I think we can form some common ground to work from, as the center you reference is indeed just a single point, which is what I have been pointing out all along, and can therefore agree with fully. It might also be useful to note that this point's position will also not vary (by much) in it's position to the receiver, or the other null point in the wave analogy.

If we set our muzzle device, in such a way, as to position the front edge of the parallel node at the crown, as you say, to take advantage of ALL of its length, to direct the bullet, should we then fire a round of higher velocity, the parallel node will shorten in length, exposing the "part cycle" to the exit of the crown. Of course accuracy suffers.

As would be expected if the "parallel node" were instead just a section of lower amplitude.

No my friend, the muzzle device need to be of a weight, and, of the proper position, in front of the crown, to move the "exact center" of the parallel node to the exit of the crown. At this point, the muzzle is stopped, requiring no further adjustment of the muzzle device.

Given consistent temperatures of the barrel I would agree. slight adjustments may be required in much warmer or cooler temps due to the fact that the barrel itself will be slightly longer or shorter - but this is a very small difference. But you do bring up a good point which has not been mentioned much before now - that of position. A lighter weight, positioned farther in front on the muzzle will have a near identical effect as a heavier one positioned closer. So it's not so much the actual weight of the "muzzle device" as it is the Moment or torque that is imparted to the barrel at that point. Something that might be of a great deal of importance to someone shooting a rifle that has difficulty "making weight".

Thank you again my friend for the advice on quotes and for the excellent question.

Your friend, Bill Calfee

You are of course welcome. and good luck on the continuing endeavor. I will continue to be very interested.

 

[Vibe]

Bill. For your convenience I've requoted my post #83 here.
*******************************************************************
There is a small box at the lower right of each post that has "Quote" printed in it. Clicking on that box automatically puts the entire post into one of the quote boxes. If you do not wish to quote the entire post, parts of it can be edited out in the same manor that your own typed text can be edited.
If you wish to break the post into several quoted boxes you must put the "quote" tags around each section of text. The quote tags for the post of yours that I quoted here are QUOTE=Kathy;390778 with the [ brackets ] around the text of the tag, followed by the close quote tag /QUOTE also enclosed in the straight brackets. (This is more clearly illustrated when you go back to edit a post with quotes in it. And these tags are more easily put into place in multiple places by copy/pasting to the various positions. Just remember that each open quote also requires a close quote for it to format correctly.)

You're welcome, and good luck at the shoot.
***********************************************************************
But the board software does not "requote" previously included quotes so I removed the previous quote tags so that you may now quote from this posting as well and not have to go back to page 6 to find post #83.

 

[Vibe]

Vibe if the rifles barrel is aimed straight at the target at the action and the muzzle is moving like a wave it will only be parallel to the target at two other points one being 90 degrees and the other being 270 degrees.
Yes at 360 degrees it will again be pointing straight at the target but that would be the same line not a parallel one.

At the other points along its length the bore will intersect the action if we make its length long enough.
Lynn

You are forgetting the effect of time, but I digress, it's a moot point because that is not the moment in time we are looking for. There is the possibility that at some instant point in time the entire barrel is a straight line. But it is in very rapid motion at that particular time and is not the point in time of bullet exit.

We are not particularly interested in when the barrel muzzle end is pointed at the target. What we are attempting to get is the muzzle pointing in a direction that will result in the ballistic curve of the bullet path intersecting the target. And doing so in a manner such that a faster bullet will travel a path that has a common target impact point as a slower bullet - such that the speed differences of the bullets no longer creates a vertical dispersion.

 

[pacecil]

To Bill and Vibe, is this of any value?

Vibe said,
.... But you do bring up a good point which has not been mentioned much before now - that of position. A lighter weight, positioned farther in front on the muzzle will have a near identical effect as a heavier one positioned closer. So it's not so much the actual weight of the "muzzle device" as it is the Moment or torque that is imparted to the barrel at that point. Something that might be of a great deal of importance to someone shooting a rifle that has difficulty "making weight".


From an old thread,
Calculating tuner dimensions....
Here's all you have to do:
Consider barrel length B, barrel diameter D, tuner length L, and tuner diameter T. Tuner is assumed to be a sleeve on muzzle end of barrel and length is measured from muzzle out to end of tuner.

The relationship between these dimensions to move the "node" to the muzzle is :
B^2/2(.2D^2-.01) = (.2LT^2-.2LD^2)(B+L/2) for steel tuner.
B^2/2(.2D^2-.01) = (.078LT^2-.078LD^2)(B+L/2) for aluminum tuner.
Put in the barrel dimensions, assume a tuner length you might want, then calculate the tuner outside diameter T. For example if you had a 24" x 1" barrel and you consider using a 4" long steel tuner you find it should be 1.9" outside diameter by 1" inside diameter.

All the above is for straight barrel. For tapered barrel use the mean diameter for D.

A tuner inside diameter equal to the barrel diameter has been assumed . If you want to decrease this by some amount then just take an equal amount off the calculated tuner outside diameter. If you want to use a solid rod for a tuner then just take the entire barrel diameter off the calculated tuner diameter.

All this should be considered as approximate since there will be a variation in how tuner is joined to barrel (especially true for a solid rod). It applies to natural vibration so has little bearing on what happens before bullet leaves barrel and thus little bearing on how "tuning" might affect accuracy.

 

[Vibe]

Thanks Paecil. Something to think about. Do you have a link to that thread? The math nomenclature is a bit difficult to decipher in that format. Hard to tell where the exponents end and algebraic factors start. I don't see a relationship for how far past the muzzle the tuner should hang either, and that is fairly important. Unless it is assumed that 1/2 of the tuner length envelopes the barrel, which may or may not be optimum.

 

[Butch Lambert]

I'm not a rimfire shooter and a poor centerfire shooter, but answer this for me. How many of the scientific and engineering type on this forum build accurate rifles?
Butch

 

[Butch Lambert]

Lynn,
Go to the thread on the centerfire forum started by Jim Borden and I believe the photos are on the second page. These were the original idea of Esten Spears, a vibration engineer with help of Varmint Al's FEA analysis. We have Esten's blessing to manufacture them.
Butch

 

[burtona]

I'd like to pose another question or three to the scientific and engineering types on this thread (or anyone else that wants to jump in).
Is it possible that the usual vibration (sine wave, etc.) patterns don't hold true as a bullet is being swaged down a barrel at high velocity, pressure, and temperature?
Is it possible nodes (parrellel or otherwise) move around while the bullet is in barrel?
Is it possible that none of us actually know what is going on with internal ballistics during the barrel time?
I suggest the answer to all three questions is YES!

 

[pacecil]

Forced vibration...

To Burtona, You are exactly right. It's been pointed out time and time again that all this discussion is centered around NATURAL vibration that probably only happens after the bullet leaves the barrel. This is the only mode of vibration that anyone can describe so Calfee and others hang their hat on that, and so that's what we discuss. Any attempt to describe the true vibration that might be going on in the barrel as the bullet leaves falls on deaf ears! The forced vibration is so complex nobody wants to consider it, so instead we just keep on talking about the natural vibration of the barrel. Varmint Al's work was concerned about forced vibration but it only involved recoil forces - not bullet forces.

 

[karlssoni]

All this talk is about "one" wave....?????Could there be more????
What if you "ring" the barrel twice, real fast,do you still have only one "wave"???????? bill

I've been thinking of this in terms of a vibrating string. Those of you who play a stringed instrument will probably be familiar with harmonics. It occurred to me that there must be an explanation online about harmonics in a vibrating bar. Sure enough, here it is: http://intuitor.com/resonance/resDemo.html

I haven't read it yet, but it appears to illustrate what Bill is asking about.