When measuring concentricity, which is the better way? Should I use the 2 v-blocks or use one v-block and the bored out spindle that holds the bullet point? What do they mean by total indicated runout verses concentricity?
Neco tool questions.
- Thread starter commando57
- Start date
NO, runout and concentricity are NOT the same thing..
OP, to check concentricity only, you pin the bullet tip with a spindle. This provides the centerline with which eccentricity is measured from. Indicate nearest the center of the case if you can.
Runout is completely different than eccentricity, as it's the sum of ALL deviations.
For this, use 2 V-blocks for case body support, while indicating off the neck or bullet nose.
Concentricity is a quality of centerline.
Runout is a quality of straightness.
A straight round is also concentric. But a concentric round can be crooked as hell.
OP, to check concentricity only, you pin the bullet tip with a spindle. This provides the centerline with which eccentricity is measured from. Indicate nearest the center of the case if you can.
Runout is completely different than eccentricity, as it's the sum of ALL deviations.
For this, use 2 V-blocks for case body support, while indicating off the neck or bullet nose.
Concentricity is a quality of centerline.
Runout is a quality of straightness.
A straight round is also concentric. But a concentric round can be crooked as hell.
bozo699
Gold $$ Contributor
Mike,
I have read your post multiple times, I can't agree or disagree as I am not sure I completely understand. How do you pin a nose of a bullet and what do you attach the case head to to check concentricity, what tool would you use? I have two Sinclair tools that I like and the new Hornady that I dislike.
Wayne.
I have read your post multiple times, I can't agree or disagree as I am not sure I completely understand. How do you pin a nose of a bullet and what do you attach the case head to to check concentricity, what tool would you use? I have two Sinclair tools that I like and the new Hornady that I dislike.
Wayne.
I doubt I can impress anything here that would stick for more than a few days.
Within a couple weeks, questions about concentricity will resurface(because nobody ever searches). There will again be canned generalizations in response, and so any previous efforts to fix misinformation, will stand as wasted.
But I’ll try once more..
As said earlier concentricity is a quality of deviations(eccentricity) from centerline. Some refer to this as runout from centerline, and while this is possible, it is not always true. You can have runout with no real centerline at all(surface runout, flaws, angle deviations, combinations adding and subtracting), or a great deal of runout with something that is very concentric (like a crankshaft).
It has to be taken in context with measurement, because both centerline and deviation are relative to measurement.
The basic measuring approaches for loaded cartridges today. V-Block and Neck Benders.
Sinclair sells a common V-Block(with bearings), and there are a bunch neck benders now, copied from Bersin. Examples are H&H, Hornady, & Bruno. I call em neck benders because they propose to ‘straighten’ ammo by doing just that..
NECO provides for both methods.
Juenke ICC is V-Block.
Let’s start with a neck bender(NB), and 4 measurement scenarios:
#1 Straight, zero eccentricity indicated.
The tip nearest the arrows is captured (pinned). The casehead is supported & furthest from the arrows. The blue arrow represents typical NB measurement point.
#2 Bowed, a small portion of eccentricity indicated
It is concentric only w/resp to both ends on axis. It could have a lot of off-axis runout that would escape measure. And regardless of generalizations, this will not chamber straight.
#3 Offset, a small portion of eccentricity indicated
Notice the ‘relative centerline’ forced by measurement method. When this round fires, that centerline will not likely hold.
#4 Bowed, ‘bullet straightened’, lower eccentricity indicated
Better than nothing, but nowhere near ‘straight’.
Now a V-Block, and 3 measurement scenarios:
#5 Straight, zero eccentricity, zero runout
The casehead is supported and captured while rolling. The bullet is free. There is never an imposed centerline here. But given that it’s straight, it is also concentric.
#6 Bowed, very high runout
Eccentricity is unknown because there is no real centerline of measure.
Because TIR is the sum of all deviations here, you cannot simply divide the reading(cheat).
#7 Offset, very high runout
Now, there is a certain truth to think over here. Or, you can actually compare one measurement method to another (I have). Go from a NB to V-Block & back, and you will instantly lose all basis for denial about it. WHY DENY IT?
I already know shooters prefer and trust low readings over high. I believe it’s because their ammo shoots well enough regardless of reading. So if they get high readings, it’s either fix it with great efforts, or merely generalize it away as bogus to their end.
Guns do shoot ‘well enough’ I suppose even with extreme runout.
But this is a completely different subject than concentricity, runout, or making straight ammo.
You get high readings because you eject cases off the bench? Or, because your kids jumped up & down on your feed sack of brass, yadda, yadda?
Whatever,, YOUR AMMO IS NOT STRAIGHT UNTIL MEASURED SO ON A V-BLOCK
And mine is…
Within a couple weeks, questions about concentricity will resurface(because nobody ever searches). There will again be canned generalizations in response, and so any previous efforts to fix misinformation, will stand as wasted.
But I’ll try once more..
As said earlier concentricity is a quality of deviations(eccentricity) from centerline. Some refer to this as runout from centerline, and while this is possible, it is not always true. You can have runout with no real centerline at all(surface runout, flaws, angle deviations, combinations adding and subtracting), or a great deal of runout with something that is very concentric (like a crankshaft).
It has to be taken in context with measurement, because both centerline and deviation are relative to measurement.
The basic measuring approaches for loaded cartridges today. V-Block and Neck Benders.
Sinclair sells a common V-Block(with bearings), and there are a bunch neck benders now, copied from Bersin. Examples are H&H, Hornady, & Bruno. I call em neck benders because they propose to ‘straighten’ ammo by doing just that..
NECO provides for both methods.
Juenke ICC is V-Block.
Let’s start with a neck bender(NB), and 4 measurement scenarios:
#1 Straight, zero eccentricity indicated.
The tip nearest the arrows is captured (pinned). The casehead is supported & furthest from the arrows. The blue arrow represents typical NB measurement point.
#2 Bowed, a small portion of eccentricity indicated
It is concentric only w/resp to both ends on axis. It could have a lot of off-axis runout that would escape measure. And regardless of generalizations, this will not chamber straight.
#3 Offset, a small portion of eccentricity indicated
Notice the ‘relative centerline’ forced by measurement method. When this round fires, that centerline will not likely hold.
#4 Bowed, ‘bullet straightened’, lower eccentricity indicated
Better than nothing, but nowhere near ‘straight’.
Now a V-Block, and 3 measurement scenarios:
#5 Straight, zero eccentricity, zero runout
The casehead is supported and captured while rolling. The bullet is free. There is never an imposed centerline here. But given that it’s straight, it is also concentric.
#6 Bowed, very high runout
Eccentricity is unknown because there is no real centerline of measure.
Because TIR is the sum of all deviations here, you cannot simply divide the reading(cheat).
#7 Offset, very high runout
Now, there is a certain truth to think over here. Or, you can actually compare one measurement method to another (I have). Go from a NB to V-Block & back, and you will instantly lose all basis for denial about it. WHY DENY IT?
I already know shooters prefer and trust low readings over high. I believe it’s because their ammo shoots well enough regardless of reading. So if they get high readings, it’s either fix it with great efforts, or merely generalize it away as bogus to their end.
Guns do shoot ‘well enough’ I suppose even with extreme runout.
But this is a completely different subject than concentricity, runout, or making straight ammo.
You get high readings because you eject cases off the bench? Or, because your kids jumped up & down on your feed sack of brass, yadda, yadda?
Whatever,, YOUR AMMO IS NOT STRAIGHT UNTIL MEASURED SO ON A V-BLOCK
And mine is…
I reverse the case and index off the other end of the bullet tip spindle. Thanks for everyones replys, they really cleared things up.
I have the Sinclair but have been intrigued by the neco, as I saw on a David Tubbs DVD that it can be used to detect banana'ed cases (cases that had big variations in brass thickness around the case?).
I read somewhere else that case neckwall thickness variation of greater than 2 thou was another indicator of banana'ed cases. Is this a worthwhile feature of the neco do many people screen for banana'ed cases?
I read somewhere else that case neckwall thickness variation of greater than 2 thou was another indicator of banana'ed cases. Is this a worthwhile feature of the neco do many people screen for banana'ed cases?
BoydAllen
Gold $$ Contributor
One little fly in the ointment...
Cases are not always perfectly round, and without verification, a reading on a cantilevered bullet may not represent what it is thought to be. Some time ago, I saw a picture of a tool that was designed to take simultaneous measurements at several points. One was in the plane of the front case support rollers (nearest the shoulder) While there is little option when measuring cases, for loaded rounds, tools that support off the bullet tip may yield useful information, even thought they do not produce readings that are identical to those that support a loaded round on the body of the case. At the days end, we are trying to present a chambered bullet so that its axis is coincident to that of the bore. I believe that the primary use of concentricity gauges should be to measure what our dies are doing, sizing cases, and seating bullets, but even fired cases can yield useful information where there is no ejector, and the application is sufficiently critical. That is, cases that come out of the chamber the straightest will probably come out of the die that way.
Cases are not always perfectly round, and without verification, a reading on a cantilevered bullet may not represent what it is thought to be. Some time ago, I saw a picture of a tool that was designed to take simultaneous measurements at several points. One was in the plane of the front case support rollers (nearest the shoulder) While there is little option when measuring cases, for loaded rounds, tools that support off the bullet tip may yield useful information, even thought they do not produce readings that are identical to those that support a loaded round on the body of the case. At the days end, we are trying to present a chambered bullet so that its axis is coincident to that of the bore. I believe that the primary use of concentricity gauges should be to measure what our dies are doing, sizing cases, and seating bullets, but even fired cases can yield useful information where there is no ejector, and the application is sufficiently critical. That is, cases that come out of the chamber the straightest will probably come out of the die that way.
Lurcher
Cases with high thickness variance bow with reloading cycles. Once it begins, it cannot be reversed.
If you want straight ammo, and you FL size, then you'll have to suck it up, cull your cases by thickness variance, and toss ~1/3 of what you buy(irregardless of brand).
There are 3 related basics here that need to be understood;
#1 initial thickness variance is full length of a case
#2 thicker brass springs back more than thinner brass
#3 sizing initiates springback
With #1, you can see full length thickness variance at the necks, with a NECK MIC. This is a better tool in every respect for measuring that. Especially important with a high cost brass.
The RCBS/NECO thickness 'feeler' is useful to see radial thinning that can occur until/up to seperations.
But you can detect this with a dental pick in hand, and by then you've had many other signs steering you towards the check, I'm sure.
Of course, long cases bow into bananas faster & harder than stubby cases. But ALL will, when thickness variance combines with excess FL sizing.
For those of you who believe FL sizing straightens cases, you need to sit down with a V-Block and measure along the way, at each part of your sizing process. This will open your eyes to little realities of brass sizing, and what's going on with it, if nothing else.
Chambers and dies are straight(way straighter than your ammo). They are not the root cause of banana cases.
Cases with high thickness variance bow with reloading cycles. Once it begins, it cannot be reversed.
If you want straight ammo, and you FL size, then you'll have to suck it up, cull your cases by thickness variance, and toss ~1/3 of what you buy(irregardless of brand).
There are 3 related basics here that need to be understood;
#1 initial thickness variance is full length of a case
#2 thicker brass springs back more than thinner brass
#3 sizing initiates springback
With #1, you can see full length thickness variance at the necks, with a NECK MIC. This is a better tool in every respect for measuring that. Especially important with a high cost brass.
The RCBS/NECO thickness 'feeler' is useful to see radial thinning that can occur until/up to seperations.
But you can detect this with a dental pick in hand, and by then you've had many other signs steering you towards the check, I'm sure.
Of course, long cases bow into bananas faster & harder than stubby cases. But ALL will, when thickness variance combines with excess FL sizing.
For those of you who believe FL sizing straightens cases, you need to sit down with a V-Block and measure along the way, at each part of your sizing process. This will open your eyes to little realities of brass sizing, and what's going on with it, if nothing else.
Chambers and dies are straight(way straighter than your ammo). They are not the root cause of banana cases.
BoydAllen
Gold $$ Contributor
A couple of other things about the creation of bananas...
The less a case expands on first firing, and the less its fired dimensions are reduced by sizing, the less its sized straightness will be affected by asymmetrical wall thickness. I believe that the the curve, for a given level of wall asymmetry, by a given chamber and die, is produced is at a more or less constant rate per inch, and for that reason, all other things being equal, longer cases are a bigger problem than short ones.
The less a case expands on first firing, and the less its fired dimensions are reduced by sizing, the less its sized straightness will be affected by asymmetrical wall thickness. I believe that the the curve, for a given level of wall asymmetry, by a given chamber and die, is produced is at a more or less constant rate per inch, and for that reason, all other things being equal, longer cases are a bigger problem than short ones.
bozo699
Gold $$ Contributor
Boyd,
Thanks for your insightful posts, I wanted to ask more questions earlier in the thread but was afraid of the consequences. Do you think the two tools I have,
the Sinclair and the new Hornady are enough to detect these problems or would the neco be a better tool? or rather what tool do you suggest?
Wayne.
Thanks for your insightful posts, I wanted to ask more questions earlier in the thread but was afraid of the consequences. Do you think the two tools I have,
the Sinclair and the new Hornady are enough to detect these problems or would the neco be a better tool? or rather what tool do you suggest?
Wayne.
BoydAllen
Gold $$ Contributor
The problem that I have with the Hornady, is that it supports the loaded round on its rim, and the rim may not be aligned with the rest of the case body, after firing, because of unequal expansion at about .3 from the head, caused by unevenness of the thickness of the case. For its type, I think that the Sinclair is the best. One of my gauges is an H&H. For those of that want one of that type, I recommend it. However I should mention that I view the proper roll of gauges as sorting and diagnosing devices. I have not spent much time with a NECO in hand, but I believe that they are well made and versatile units, that can be set up to do more tests than any other single unit of the same quality, that is readily available. So, do I get the most vague and evasive award?
BoydAllen
Gold $$ Contributor
Yes it is a home built device. My friend made it to gauge case wall thickness runout back near the head. He sorts that way. I should have taken a picture without the case. the mandrel has an offset so that it only touches the inside of the case opposite where the indicator touches the outside. There are interchangeable sleeves that fit various calibers' necks, and a stop collar, as well as the bracket near the back of the case that keeps it aligned side to side. He can sort cases really quickly with this tool. His has a busy retirement, and his legs and back won't take as much shop work as in the past, or I would have one. Interiors of cases can be offset parallel or canted,with respect to their exteriors, so what you get at the neck may not tell what you have farther back, and unlike the necks, that can be turned, you are stuck with the consequences of runout farther back. I was the one that told him about Creighton Audette's writing on this subject. He took the ball and ran with it. That was many years ago.
Ok so you are performing the same measurement as seen here in the Riflemans Journal. It is stated that it takes about two minutes to screen each piece of brass. In a box of lapua or norma brass have you done enough screening to say roughly how many pieces you would expect to find with greater than 3 thou runout at the web?
How about cheaper brass? The DVD I watched where David Tubbs performed this screen on the Neco tool he also mentioned indexing cases to ensure that thick/thin regions were aligned with the bolt lugs. Are you going that far?
How about cheaper brass? The DVD I watched where David Tubbs performed this screen on the Neco tool he also mentioned indexing cases to ensure that thick/thin regions were aligned with the bolt lugs. Are you going that far?
Good article.
The article had a focus on Creighton's contention that thickness variance -near caseheads, had a measurable affect on fired chamber alignment. I believe it.
Not addressed(beyond the scope) is that the original thickness variance in the 'cup' follows through to the finished case form. That is, the variance tapers with thickness from webs all the way to mouths.
So you might see 1thou of variance at the necks, that would measure 3-4thou taken all the way down near the webs(where all brass is thicker). The correlation could also be different depending on cartridge & brass brand.
You can see this with your NECO, but I recommend a ball mic over an indicator & probe.
With regard to thickness variance, it's my observation that no brand or lot of brand can be predicted as better than another. I've seen both the best & worst from Lapua, Norma, & Winchester.
What was also seen but not addressed was that FL sizing aggravated the condition. I believe this too
The article had a focus on Creighton's contention that thickness variance -near caseheads, had a measurable affect on fired chamber alignment. I believe it.
Not addressed(beyond the scope) is that the original thickness variance in the 'cup' follows through to the finished case form. That is, the variance tapers with thickness from webs all the way to mouths.
So you might see 1thou of variance at the necks, that would measure 3-4thou taken all the way down near the webs(where all brass is thicker). The correlation could also be different depending on cartridge & brass brand.
You can see this with your NECO, but I recommend a ball mic over an indicator & probe.
With regard to thickness variance, it's my observation that no brand or lot of brand can be predicted as better than another. I've seen both the best & worst from Lapua, Norma, & Winchester.
What was also seen but not addressed was that FL sizing aggravated the condition. I believe this too
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