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Rifles, Reloading, Optics, Equipment
Reloading
Help me determine what is causing my runout!
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<blockquote data-quote="boomtube" data-source="post: 304035" data-attributes="member: 9215"><p>"..if your runout is caused by big variance in thickness, this will be indicated regardless of centerline conditions. And in this case, your runout would be exactly as indicated(provided that is your only contributer)."</p><p> </p><p>If I correctly interprete your meaning, you are suggesting a potential for the neck ID to be exactly paralllel to the OD but off-set by what ever neck thickness variation that exists? </p><p> </p><p>IF I do understand you correctly - and I may not - I don't agree with your perceived view of gaged TIR vs. actual run-out. The high side will read one level of error away from the true center line. A reading on the other side will read the same off-set but in the opposite direction. So, no matter the source of error, the indicated reading will effectively be twice the amount of actual run-out. That's just the way TIR works, regardless of the source cause of the error. (And a tip of the hat to AJ)</p><p> </p><p>I'm told that many non-machinest's have some difficulty grasping the difference between run-out and TIR and how either is measured. (I'm NOT a machinist but I've had a good deal of hands-on lathe training from someone who is.)</p><p> </p><p> </p><p>"I also do not follow the collet die as a runout reducer idea. I just don't see how it would. What I see, is that it would contribute less towards additional runout."</p><p> </p><p>Again, if I understand, it's hard to differentuate between not adding runout vs. correcting it. To some slight degree, the Lee collet die does both. </p><p> </p><p>First, unlike a conventional small sizer button dragged through the neck, the Lee collet die cannot ADD any "bend" to a neck since the neck is squeezed hard against the straight, centerally mounted and firmly held mandrel. That's good, and it's unique to that die.</p><p> </p><p>Second, if the inner case neck was originally formed with some anglular difference to the outside, the fact that the inside is forced so hard to the mandrel there will be some amount of straightening force applied. Including springback, there are too many variables in that for anyone to project just how much such a straightening would remain after the sizing pressure is removed but it sure can't get worse and it MAY be improved.</p></blockquote><p></p>
[QUOTE="boomtube, post: 304035, member: 9215"] "..if your runout is caused by big variance in thickness, this will be indicated regardless of centerline conditions. And in this case, your runout would be exactly as indicated(provided that is your only contributer)." If I correctly interprete your meaning, you are suggesting a potential for the neck ID to be exactly paralllel to the OD but off-set by what ever neck thickness variation that exists? IF I do understand you correctly - and I may not - I don't agree with your perceived view of gaged TIR vs. actual run-out. The high side will read one level of error away from the true center line. A reading on the other side will read the same off-set but in the opposite direction. So, no matter the source of error, the indicated reading will effectively be twice the amount of actual run-out. That's just the way TIR works, regardless of the source cause of the error. (And a tip of the hat to AJ) I'm told that many non-machinest's have some difficulty grasping the difference between run-out and TIR and how either is measured. (I'm NOT a machinist but I've had a good deal of hands-on lathe training from someone who is.) "I also do not follow the collet die as a runout reducer idea. I just don't see how it would. What I see, is that it would contribute less towards additional runout." Again, if I understand, it's hard to differentuate between not adding runout vs. correcting it. To some slight degree, the Lee collet die does both. First, unlike a conventional small sizer button dragged through the neck, the Lee collet die cannot ADD any "bend" to a neck since the neck is squeezed hard against the straight, centerally mounted and firmly held mandrel. That's good, and it's unique to that die. Second, if the inner case neck was originally formed with some anglular difference to the outside, the fact that the inside is forced so hard to the mandrel there will be some amount of straightening force applied. Including springback, there are too many variables in that for anyone to project just how much such a straightening would remain after the sizing pressure is removed but it sure can't get worse and it MAY be improved. [/QUOTE]
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Reloading
Help me determine what is causing my runout!
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