nodes...

[martin hammond]

Beau, two questions on how Bill is tunning, if done with one speed of ammo aren't you in the future limiting your available lots to a limited speed selection. and if you go to one spot and one weight setting how do you know you have squezzed the last thousandths of accuracy from your rifle? you may have a world record setting rifle and never know it.

 

[Vibe]

Now, you want to answer that question that I asked Vibe. He doesn't seem to want to. The rod vibrates in an X pattern. What is the intersection of the X called in your terminology and is there any point it actually stops? By the way, if the arm of the X is moving one way past the intersection, does it move the other way on the other side? These are serious questions (or at least as serious as you can get with this stuff). I really want to know.

I'm SO terribly sorry you missed where I DID answer you, and that you might not have been able to understand it. I work nights and do not necessarily operate on YOUR schedule. Deal with it.

Does it actually stop? yep, several times - right before it reverses direction - just like any other vibrating system. And if you can get the bullet to exit at that point it WILL eliminate a lot of accuracy robbing variables.

Does the other side of the node go up as this side goes down? Well yeah, there are no forces in the system to induce a "bend" of that nature in the barrel. Though there would have to be several for the node to be longer than a point. The original vibration (well the largest harmonic anyways) is in no small part due to the fact that the barrel was "drooping" before the shot (due to gravity) and rearward acceleration ,increased internal pressure, and reaction to the bullets inertia are trying to rapidly reduce that droop. But Al has that pretty well modeled - which model also shows no magical "parallel node" that remains straight in the midst of several other sweeping curves.

What you said about the teter toter is almost (I won't say exact because I'm not exactly sure) what Bill is saying about the node staying parallel to the axis, thus the name the "parallel node". There could be better terminology and he freely admits that

Not when he was posting on here, he didn't "freely admit" anything could be done better. And the teeter totter example is as close as any...though if you were to mount the teeter totter pivot on springs it would be closer still.

 

[cobra1]

Can any admin. comment why my hour long (preparation) was not posted on the second day? It's possible I screwed up and did'nt get it properly posted. There seems to be no record of it?

I spent considerable time explaining the physics going on.
Look at Varmintal's one page where he discussed the first 8 modes of vib.
Vib understands it. There are no X modes? not flats or parallel nodes.

The barrel inital starts in a mode one vib at 1/4 wave length; with a tuner I think most barrels start to integrate a mode 2 into the mode one. After that it does'nt matter; these a 80-140 hz modes and after one cycle, bullet in gone in about 1 1/2 MS.
The vise/rod discussion confuses me or I don't understand the point. If I put a rod in a vise, displace the end, the fixed end stays put, the rod starts ossicilating in a 1/4 sine wave, where the end goes up/down, at the top and bottom the vert. velocity is zero, at the middle(straight) the rod is prrallel/straight at has the highest verticle velocity at that instant.

There is multi-variable dynamic physics going on and this discussion is only grazing the complexities. Even Varmint good explainations are by his own decree first order and only assume one plane of motion. I would recommend very one interested in this great discussion study al's many FEA's as they are very good.

cobra1

 

[Boyd Allen]

While I don't often monitor rimfire threads or comment on them, you question about your lost post has prompted me to make a suggestion, so that your problem does not reoccur.

If you will compose your post in a word processing program, save the document, and then copy and paste its content into the message composition window on whatever site, board, or thread that you want to post on, if there is a posting glitch, your work will not be lost. I don't think this is needed for a short post, but for an hour long effort, I think it well worth the few additional seconds that it takes. It also has the advantages of allowing one to use spell check, and other correction tools. (not that you need them, but I do)

 

[B. Harvey]

The node present in the barrel, is telling us what frequency the barrel is going to vibrate at by measuring the half wavelength, from action (node) to the node in the barrel. It also tells us that since it only has one node, it is in the second mode for a fixed-free beam. Ringing the barrel, fitted, and free, confirms this on the rifles I have access to. After studying this stuff for a while, these are the conclusions I have come to. Still tells nothing about what a rifle wants as each are different.

http://paws.kettering.edu/~drussell/Demos/Flexural/bending.html

 

[Varmint Al]

Engineering Eye Candy

Engineering Eye Candy.... Here is a 30" long 1/4" square steel rod. The left end is rotated 4.7 degrees in 5 ms. The dynamics of the rod are shown for 50 ms. The red fringe of effective stress is 20 ksi and the dark blue fringe is 0 ksi. This is sort of getting back to the original question pacecil asked. This is a much greater moment than is applied to a barrel, but it gives and idea of the motions.

Good Hunting... from Varmint Al

 

[martin hammond]

I never thought croosing your t's, dotting your I's, teeter totters, 30" steel rods and the true definition of patterns played such a large role in shooting a .22. here all along I thought $12 a box of ammo a good scope and a accurate rifle is all that was needed. and I'm still trying to determine what is really is.

 

[Fred K]

"Is" is not what you think Martin !
Fred K

 

[Beau]

Beau, two questions on how Bill is tunning, if done with one speed of ammo aren't you in the future limiting your available lots to a limited speed selection. and if you go to one spot and one weight setting how do you know you have squezzed the last thousandths of accuracy from your rifle? you may have a world record setting rifle and never know it.

If the tuner is set correctly, it should never need to be moved regardless the speed of the ammo.

 

[Beau]

I'm SO terribly sorry you missed where I DID answer you, and that you might not have been able to understand it. I work nights and do not necessarily operate on YOUR schedule. Deal with it.

Actually, you didn't answer, and according to the website you were online. Possibly, you chose to go back to work instead of screwing around. I'm gonna rephrase that last statement. It was made in haste. You are knowledgeable but just a little stiff in your thinking.

And you pretty much admitted that there is nothing wrong in the phrase "parallel node". That's all I needed to know.

 

[Lynn]

Pacecil

Beau, Lynn, and some others are completely missing a point here. They keep saying Bill is just saying he sees something in the vibrating barrel that he calls "parallel" or "straight" or "stopped". We are just misunderstanding his "words", or we are misunderstanding his meaning. Bulls***!!! For God's sake, he drew a picture of what he saw - is everyone blind!!!!!

Pacecil
Nobody here is Blind.
The picture Bill drew is of the node placed at the muzzle.None of the modeling shown so far has the node at the muzzle.In all of the pictures the node is 2-3 inches from the muzzle.
We also don't see the anti-node anywhere near the muzzle in any of the modeling.
The area just before and just after the anti-node is the slowest area in the barrels vibration pattern.If you add a weight ahead of the muzzle and dampen the amplitude it appears wider just like in Bills picture.
Waterboy

 

[martin hammond]

beau, here is what I am asking. if the normal range of spread for eley black box is 20fps and you are using 1052 speed to set your tuner then it may be set for ammo in the 1042 to 1062 range. and if here in the US we receive 200 lots of black box a year only a fraction of that ammo will be in that range. if a tuner is set for speeds between 1040 and 1080 then the chances of finding multiple lots that are outstanding increase. I can see where tunining to one speed would be quicker but it would also narrow what ammo choices a shooter has.

 

[Lynn]

Vibe

Vibe
I described the teeter totter several years ago and Bill said it wasn't an "X" like the teeter totter example.

So far all of the discussion has been with the muzzle moving upwards at a very fast point in the barrels vibration pattern.Everybody is looking at a short 2-3 inch segment of the barrel just ahead of the node and nobody is saying anything about the anti-node moved to the muzzle.

If the anti-node is the slowest section in the barrels vibration pattern and we move it to the muzzle what can we expect to see with and without the tuner added.If we were on the barrels upswing would this slower area be benificial or detremental?
If beneficial and we then dampened it with a weight it should work even better.
Also in looking at Varmint Al's modeling from a couple pages ago specificaly on the 22 Long Rifle was I the only one that saw the results of the reverse tapered barrel? The best that barrel ever shot was with the reverse taper and without the tuner.In comparing the reverse taper to the other barrels mentioned why would anyoner shoot anything besides the reverse tapered barrel?
Waterboy

 

[martin hammond]

I'll bet the shooter that took out all the bulls on the ara target shown on this forum had a lot less than a .090 spread.

 

[Varmint Al]

Lynn,
The velocity spread of the ammo in the calculation was very large. Good ammo would have much less velocity spread.

Martin,
I would also expect that the velocity spread of his ammo was much less than 1035 to 1075 fps. Those were the numbers used in the calculation. A smaller spread could have been used but the idea was to show a relative effect between different configurations.
Good Hunting... from Varmint Al

 

[Beau]

beau, here is what I am asking. if the normal range of spread for eley black box is 20fps and you are using 1052 speed to set your tuner then it may be set for ammo in the 1042 to 1062 range. and if here in the US we receive 200 lots of black box a year only a fraction of that ammo will be in that range. if a tuner is set for speeds between 1040 and 1080 then the chances of finding multiple lots that are outstanding increase. I can see where tunining to one speed would be quicker but it would also narrow what ammo choices a shooter has.

Nope, you don't get it, no offense. Tuned is tuned. You cannot tune for different speed ammo. You're tuning the barrel. Now you may believe that is a Calfee idea and he certainly expanded on it, but ten or so years ago Calfee and I disagreed on how a tuner worked. If you could get the old archives and the "PE" posts, you would see. Now if the ammo is capable, your tuner only makes it better, it will not make bad ammo good, but if you screw it up, you can make good ammo bad. That's the 42 yard thing you keep seeing. Now however much you want to buy into the nodes and the engineering is up to you. How much you want to buy into tuners is up to you but they do work to an extent. However, they are not miracle workers. Maybe on an ARA target, they get you 100 points, but that's the match. Anyway, once tuned, the tuner should never need touching again, if it's correct. Now I have a very good friend who twists his like a helicopter rotor and he probably would disagree and you may disagree. That's fine. You have to find your own way. But I've know for better than ten years, that once tuned, you don't need to touch it again. Faster ammo is a problem because of wind. The wind affects it more, but the fastest ammo I have gives me the best groups. If those groups would stay true across the target, and they will assuming no other outside influence, that ammo would always shoot 2500's. 2500 ammo is not hard to find, it's just hard to do in practice. It takes a lot coming together and mostly it's the shooter on the line. Because the shooter has already made sure he or she has a good rifle, good ammo, and good tune. The rest is mental. And I don't mean in the head. I mean you have to figure out what to do. At that point it's no longer theoretical and there's no time to work out a physics equation. You just have to do. Give engineers their due. Most of this stuff we wouldn't have without them. But when they're on the line with you, they have no advantage that you can't match. Whether you do or not is up to you.

By the way, I'll add this. Bill Calfee may not be Isaac Newton, but he understands rifles and shooting like no other person I've ever met. Engineers may like to ridicule his words and his work but they can't match it.

 

[Lynn]

Varmint Al

Al
In your opinion is there any advantage to moving a node or anti-node to the muzzle? Other than needing less weight to get the same affect is there any advantage to a longer tuner?
On a rifle without weight restrictions is there any advantage?

Waterboy

 

[nipper]

beau, my builder told me leave the tuner alone mostly, unless you change lots and if so you might need to either go +5 lines at the most or - 5 lines at the most, and i have found this to be correct, all i need is more practice on reading my wind flags

bill

 

[Varmint Al]

Engineers may like to ridicule his words and his work but they can't match it.

As an engineer, I have not tried to tell anyone how to tune a rifle or where to position the tuner. What I have done is try to give some incite on what a rifle does when it is fired and how a tuner and/or a flexible barrel responds when the rifle is fired. I have not tried to ridicule anyone. I have merely tried to explain a very power analysis technique of rifle behavior.

Good Hunting... from Varmint Al

 

[pacecil]

Lynn said, The picture Bill drew is of the node placed at the muzzle.None of the modeling shown so far has the node at the muzzle.In all of the pictures the node is 2-3 inches from the muzzle.
Lynn, Lynn, Lynn, in my very first post, the second picture is exactly what Bill drew in P. S. and in this forum. Maybe you are blind! But in any case you aren't paying attention. The node at the muzzle with a tuner is shown in my second post. Now, maybe Bill did also draw a picture like this somewhere, but all the "modeling" in this thread is just like what Bill has pictured. I don't think Bill has done anything we haven't shown in this thread.

We also don't see the anti-node anywhere near the muzzle in any of the modeling.
This is insane! What are you looking at? Everyone that has shown the vibration pattern shows the "antinode" at the muzzle! I give up, I guess you're going to come back at me and say, Yeh, but it isn't what I call the antinode. No, more likely you will come back with, Yeh, but that isn't what Bill calls an antinode.

The area just before and just after the anti-node is the slowest area in the barrels vibration pattern.If you add a weight ahead of the muzzle and dampen the amplitude it appears wider just like in Bills picture
This isn't insane, it's just stupid. You are just using words with out a hint as to their correct meaning. I guess however since it is so screwy, I can't be sure I can really interpret what you are trying to say. The area I think you are describing is actually traveling the fastest, not slowest.....sometimes! You see there is no point traveling with constant velocity (except the nodes which have zero velocity) At any instant you will find any point you want, and it will be traveling faster, or slower, than any other point. That's "scientific" gibberish and I know you will ignore it!
Now, as to "the amplitude being wider". That's like saying as you get older, your height gets wider???? Boy, I have to admit I just never saw Bill's picture iwith a wide amplitude.