Tuners Spinning Out Of Control

Bobby T. said:
Dang i learned about words i don't hear every day they flow real good when put into a sentence. anyone else scratching their noggin.
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stick around you'll probably be learning all kinds of new words this weekend. like being in
denial is not being in a river in egypt.
 
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well Tomc I'm sure glad these that I'm working with are called tuners, thats more appropiate than harmonics modulator, or adjustable muzzle brakes. everyone now knows when I say tune, that refers to a slower round exiting the muzzle at a higher angle than a faster round. doing all this while in a upward sweeping motion. we now know it's silly to say the muzzle is stopped, hopefully in the future the term muzzle stopped will be shelved, just plain silly.
 
I worked at Western Electric in Cicero IL many years ago; in one section of the plant they made wire, started out as 1/2" copper coils and ended up about the size of a human hair. Me and my partner sat there and watched the process for a while, I guess that makes me an expert on tuning .22lr barrels, not.

minutiae

Thanks, Douglas
 
Douglas said:
I worked at Western Electric in Cicero IL many years ago; in one section of the plant they made wire, started out as 1/2" copper coils and ended up about the size of a human hair. Me and my partner sat there and watched the process for a while, I guess that makes me an expert on tuning .22lr barrels, not.

minutiae

Thanks, Douglas
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You had a better machine than we did then. Our 600hp unit only started with 3/8" coil and took that down to 14 guage, but usually we stopped at 12. Then it went to smaller machines to take it down to 30.5 guage (which is still around 0.010" dia). To have a machine that could take it all the way in one run must have been something to watch. How much ear protection did you need to watch the wire coming off at supersonic speeds?
 
Douglas said:
I worked at Western Electric in Cicero IL many years ago; in one section of the plant they made wire, started out as 1/2" copper coils and ended up about the size of a human hair. Me and my partner sat there and watched the process for a while, I guess that makes me an expert on tuning .22lr barrels, not.

minutiae

Thanks, Douglas
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the trouble with the world is not that people know to little, but that they know so many things that ain't so.
 
Back in the late 60's early 70's i worked for Humble oil. We made gasoline from crude oil BUT we did use a lot of copper wire in out instruments. The copper wire was burred underground in red died concrete. We couldn't made gasoline without the copper wire. thanks guys. I can now make good copper wire and tubing but i still can't shoot! just too many people that know too many things that ain't so seems to be my problem, lol.... joe
 
Vibe said:
See. There is where the specific moment of inertia of the tuner comes into play. At the top of the 1st order swing the muzzle is at the 1st order anti node - with the correct tuner mass this is also when the bullet exits. However this point is also the first 2nd order node - where angular velocity is at it's highest - and with a tuner with the correct Moment of Inertia this angular motion compensates for relatively small variations in muzzle velocity. Also I think I'm seeing that the sudden increase in barrel diameter of some of the reverse taper barrels might even mimic a condition, which could be mistaken for a "parallel node" - in that it is structurally removed from the propagated stress waveform - and results in a short straight bore section at the muzzle.

At the instant of the bullet leaving under these conditions there would be no yaw imparted to the bullet by a barrels transverse motion. the muzzle would be an instantaneous pivot point, being essentially stationary in the 1st order motion as well as the 2nd order, the short straight section would allow bullet stability to form while still in the choked area, and the escaping muzzle gasses would pass almost uniformly around all tangents to the bullet. Elimination of all of these sources of initial bullet yaw would have to help maintain a stable trajectory down range.
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Vibe,
Your first and second mode model of barrel motion is an attractive one, and may be useful for conceptualizing how a tuner might work, but barrel (really, rifle) motion is more complicated.

First, assuming the first mode begins when the bullet enters the barrel, it would reach the top of its swing in a quarter cycle, about 3.1 milliseconds for the barrel without tuner that Al simulated. Even a rimfire bullet leaves sooner than that, about 2.6-2.7 milliseconds. Adding a tuner would make the first mode even slower.

Second, the whole natural frequency/mode shape description of vibration doesn't apply until the initial impulse creating the motion has propagated throughout the barrel, i.e., for times much longer than the product of the length of the barrel times the wavespeed. You can see this time in Al's simulations. For the fastest (longitudinal) wave, it takes about 0.7 milliseconds for the muzzle to move at all, even though large motions began earlier at the breech. Multiply this time by, say, 100 to estimate the time when periodic vibrations fully develop, about 70 milliseconds. By then, the bullet has been gone for at least 67 milliseconds. Like Al says, (paraphrasing here) the barrel is like a guitar string and the powder like a pick. The bullet leaves while the pick is still plucking the string. The steady state vibration happens later, much later.

A better simplified model of barrel motion might be that of a transverse traveling wave. You can see this in Al's simulations, too (for instance, http://www.varmintal.com/a22lr.htm). The wave starting at the breech reaches the muzzle in about 1.5 milliseconds and raises the muzzle angle to a peak, then bounces back toward the breech. Timing bullet exit to the upslope before the second peak in muzzle angle at about 3 milliseconds would tune the rifle.

Cheers,
Keith
 
Keith I wish you and Vibe would make up your minds.......... are you know telling me I may need 2 rolls of aluminum tape???????? thanks martin
 
I know Keith, it's an over simplification. The transverse wave explanation is probably more accurate, but much harder to model. Remember Bills example of a thin rod stuck in a vise with a standing wave vibrating on it...take that example and run a pressure wave from vise to tip, simulated by moving a slightly oversize tube from vise to tip - the period of the vibrations gets progressively shorter. In the thin rod example these final vibrations can get quite vigorous - and a tuner would help to slow these down - but again it is a function of the Moment of Inertia of the tuner to keep the angular oscillations under control - not so much the gross weight.
I really have no idea how much Als simulation took the increase in barrel stiffness, behind the bullet, due to increased pressure, into account. But I do know that a tube containing pressure is much stiffer than the same tube with no internal pressure.
 
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Vibe said:
You had a better machine than we did then. Our 600hp unit only started with 3/8" coil and took that down to 14 guage, but usually we stopped at 12. Then it went to smaller machines to take it down to 30.5 guage (which is still around 0.010" dia). To have a machine that could take it all the way in one run must have been something to watch. How much ear protection did you need to watch the wire coming off at supersonic speeds?
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I don't know beans about making wire/tubing, i was just at Western Electric working as a pipe fitter. I don't know beans about tuning a rifle either, which is why i'm here on this board.

minutiae

thanks, Douglas
 
martin hammond said:
Foster 2 rolls of tape = 5 grams per rifle, I have quite afew rifles. martin
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Make sure it's that SHINY Aluminium tape...I'm thinking some of the folks here would really like it if it were shiny...maybe with a few sparkles of glitter thrown in for good measure.

And some plumbing tape for douglas.
 
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Foster Arvin said:
Dang! Martin, at 2.5 grams per roll. you're going to have one heck of a tape ball on the end of your rifle to get the 3.3 oz you'll finish up with.

Foster
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Foster, when the tribe sent out their best and brightest wire specialist in mr nobody, I knew it was game, set, match. martin
 
DSCN1367.jpgDSCN1366.jpg foster the heavy barreled 40x has the most tape, brings it to a whopping 4.8oz Foster the others are under cover untill the first spring shoot. martin
 
Foster the 2 40x's there, one hb and the other standard both have factory chambers. the 3 reverse tapers have eps chambers and they will shoot anything.
 
foster sssh. you'll let the cat out of the bag. by the way marty uses special
2 ply tape when he needs a couple extra grams without the bulk.
 
Foster Arvin said:
Jim, Martin was keeping that 2 ply secret to his self. now Jerry had Gene rechamber and crown that 40x, but it sure shoot GOOD.
Fred Willis from Ashland had a couple of standard weight balleled ones that shot good too. I see Martin or Jr.? is posting over on Wally's site.

Foster
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foster, I would not reward their bad behavior by posting over there. they need the info I have, I don't need what they have. lol
 
uhoh it looks like we have an unidentified marty posting on another forum,
it ain't me, will the unknown tuner please step forward. i have a pretty good
idea, as the spellings a dead giveaway. maybe the unknown kathy will make
an appearance as well.
 
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i think i detect a kentucky accent in that post of the other marty.
 
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