Acceptable case wall thickness variation after neck turning

[Petrov]

Hey guys what is acceptable case neck thickness after neck turning?
I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

 

[Big Z]

I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

I'm afraid I'm going to have to go with: that's fine

 

[Victor N TN]

Try keeping more oil on both your cutter and the mandrel.

 

[High Binder]

Hey guys what is acceptable case neck thickness after neck turning?
I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

Congrats! That's an incredibly small variation, you're approaching radio wave accuracy in your turning.

Really, being that you meant .001 - .0015 or in other words half a thou, I'd say you're doing just fine. I shoot for 15-16 thickness on mine and as long as it falls within that 0.001" I call it good.

 

[mdmp5]

Hey guys what is acceptable case neck thickness after neck turning?
I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

You type one too many zeros there? If not, what are you using to measure such a small amount of thickness?

 

[Wheres-Waldo]

.0005 or less on new brass, if its older neck turned brass and I'm just cleaning up what flowed into the necks, I'm happy with .001 or less. I try not to chase a thinner neck dimension just to get a full cut all the way around the neck.

 

[Petrov]

You type one too many zeros there? If not, what are you using to measure such a small amount of thickness?

A micrometer with .0001" resolution the 5th number is me guesstimating as the hash marks dont exactly align and I have good eye sight and see which way they are going :0

 

[High Binder]

A micrometer with .0001" resolution the 5th number is me guesstimating as the hash marks dont exactly align and I have good eye sight and see which way they are going :0

That's one hyper sensitive analog "hash marks" micrometer! I'm surprised you can even make out the hash marks being that there are 10 hash marks for every .001". You must have paid millions for that because you have the only one in existence. Petrov, the way you're reading it is wrong. What you're saying is that your analog mic can read 1/10 of 1/1000 (1/10,000) of an inch and that your guesstimating the .00005 which is 5/10 of 1/10 of 1/1000 (5/100,000). This is not the case as even the hash marks for 1/10 of 1/1000 would appear as a solid line on the mic as the hash marks are bigger than the increments themselves.

Just as an FYI: the number your reading on you mic is 1/1000 of an inch or .001 which is it's actual "resolution" anything in between (1/10,000) which is the position you're guesstimating is bogus. You're better off just choosing the closest thou and reporting/recording it as such, i.e. .0015 = .002 etc. and this is especially true on a clutch-less mic.

 

[Assault116]

That's one hyper sensitive analog "hash marks" micrometer! I'm surprised you can even make out the hash marks being that there are 10 hash marks for every .001". You must have paid millions for that because you have the only one in existence. Petrov, the way you're reading it is wrong. What you're saying is that your analog mic can read 1/10 of 1/1000 (1/10,000) of an inch and that your guesstimating the .00005 which is 5/10 of 1/10 of 1/1000 (5/100,000). This is not the case as even the hash marks for 1/10 of 1/1000 would appear as a solid line on the mic as the hash marks are bigger than the increments themselves.

Just as an FYI: the number your reading on you mic is 1/1000 of an inch or .001 which is it's actual "resolution" anything in between (1/10,000) which is the position you're guesstimating is bogus. You're better off just choosing the closest thou and reporting/recording it as such, i.e. .0015 = .002 etc. and this is especially true on a clutch-less mic.

Actually Mitutoyo makes MANY mics with resolution to .00005, That said, I'm guessing you are most likely correct in that he's adding a 0 in his representation and those mics are all in a digital configuration, and while spendy, they are in the low thousand dollar range. (EDIT: not anymore, they are flat out cheap relatively these days) There are also many made to .0001 that are not digital and if that's what he has he could indeed be seeing between .0001 and .0002 and coming to the conclusion of .00015.

http://www.mitutoyo.com/wp-content/uploads/2012/09/B-US-1002.pdf

In reality though, anything less than .001 is pretty damn good and argument beyond that is academic at best.

 

[High Binder]

Actually Mitutoyo makes MANY mics with resolution to .00005, That said, I'm guessing you are most likely correct in that he's adding a 0 in his representation and those mics are all in a digital configuration, and while spendy, they are in the low thousand dollar range.

http://www.mitutoyo.com/wp-content/uploads/2012/09/B-US-1002.pdf

"Actually":

He specifically said he was using an ANALOG mic, NOT digital. My comment to cost and that there zero in existence is to that aforementioned point, i.e. there are ZERO analog mics that measure to that degree of accuracy.

 

[Powermac]

Well if he has the newest type high precision mic from Mitutoyo, MDH dseries, that gores for a little under 2000 dollars.
Those measurements are accurately measureable if your consistent enough, when measuring.
Now if they only release a tube version for neck measuring.

MDH Micrometer High-Accuracy Sub-Micron Digmatic Micrometer

As to the Ops numbers there is quite a chance there is a 0 too much.
But there is equipment that does accurate enough readings for that, for anyone saying no.

 

[Assault116]

"Actually":

He specifically said he was using an ANALOG mic, NOT digital. My comment to cost and that there zero in existence is to that aforementioned point, i.e. there are ZERO analog mics that measure to that degree of accuracy.

Please see the rest of my post that I updated, Mitutoyo DOES make analog mics the read 1/10,000 resolution, and no the hash marks are not so close that you can't land between them and reasonably infer 5/100,000 of an inch give or take. See page B-9 of the pdf I linked, the series 101 Mitutoyo mics. So my point still stands and yes he possibly could be seeing exactly what he's saying, although I agree that he's most likely adding a 0 unless he's turning necks on a tool room lathe with perfect setup EVERY time.

 

[High Binder]

http://www.mitutoyo.com/wp-content/uploads/2012/09/B-US-1002.pdf

Damn, I'd hate to be the guy threading those. So what they're really doing is sacrificing the ability to measure longer lengths for accuracy. Now I have to go buy a new set of ball mics and I agree, there's no way mics with this amount of accuracy are being used outside of a tool/die room, that's way overkill and surely not for the general public. When I worked as a tool/die maker we used mics with such accuracy but they were all digital.

 

[Assault116]

Damn, I'd hate to be the guy threading those. So what they're really doing is sacrificing the ability to measure longer lengths for accuracy. Now I have to go buy a new set of ball mics and I agree, there's no way mics with this amount of accuracy are being used outside of a tool/die room, that's way overkill and surely not for the general public. When I worked as a tool/die maker we used mics with such accuracy but they were all digital.

Precisely,no pun intended, with the caveat that they can still (theoretically) measure longer travel lengths, but at the sacrifice of a LOT of turns on the barrel of the mic (literally 10 times the turns) but for these uses they don't typically need the travel length so that would be a more rare mic. But yeah, it's pretty amazing what modern tooling and techniques is producing these days. How'd you like to be the guy at the cal/cert lab tying to make sure they're accurate hahaha. Or worse the poor bastard that's producing the calibration equipment.

 

[M40_A1]

What are your guys talking about?! Every analog micrometer (is there even such a thing as a digital micrometer?) I've handled reads to .0001" on a separate vernier scale. They are nothing new, and they were around for eons before digital anything came out.

 

[Assault116]

What are your guys talking about?! Every analog micrometer (is there even such a thing as a digital micrometer?) I've handled reads to .0001" on a separate vernier scale. They are nothing new, and they were around for eons before digital anything came out.

Digital Micrometer


Standard/analog



The majority of standard/analog micrometers made/sold have a .001" resolution not .0001" That is somewhat changing because of the reduction in costs in recent years.

The fact that you don't know there are digital micrometers made illustrates your understanding of the subject IMO. Yes .0001 resolution mics have been around for a while, but they were until the last 10-15 years or so (maybe even more recently) out of reach of the average joe due to cost. Modern manufacturing tooling and techniques have brought the cost of producing highly accurate measuring tools down considerably to the point where they are no longer out of the realm of possibly being purchased by the average joe who has a lathe in his garage.

MITUTOYO Micrometer,0-1 In,0.0001 In,Friction - Micrometers - 4CGA3|101-117 - Grainger Industrial Supply

^^^ That one for instance, is $154 from Grainger, 15 years ago it would have been 5-10 times the price.

MITUTOYO Electronic Micrometer,1-2 In,0.00005 In - Micrometers - 4CGF8|293-336 - Grainger Industrial Supply

^^^ That one is the digital one that measures to .00005 (5/100,000 ths) for $327 that kind of resolution would have been in the thousands of dollars 10-15 years ago, if even available (dunno, it's been too long and I've slept since then, also we had no need for that kind of resolution)

I used to be responsible for buying tooling for the inspection group in a manufacturing company I used to work for, thus my knowledge (although somewhat dated) on the subject.

 

[M40_A1]

The majority of standard/analog micrometers made/sold have a .001" resolution not .0001" That is somewhat changing because of the reduction in costs in recent years.

The fact that you don't know there are digital micrometers made illustrates your understanding of the subject IMO. Yes .0001 resolution mics have been around for a while, but they were until the last 10-15 years or so (maybe even more recently) out of reach of the average joe due to cost.

!

The photo you posted of the analog micrometer ad shows .001" graduations, yet +/-.0001" resolution, and that (I would logically assume) is made possible by a vernier scale. There's no super tooling involved. All that is involved is making a normal quality micrometer with no unreasonable backlash and marking a vernier scale in the right place. Heck, the one-inch micrometer I have always used and I am now holding was bought by my Dad in the 1970s, and it has the .0001" vernier, and it is a ...hold on to your hat......Sears Craftsman tool. My Dad didn't pay some exhorbitant amount for this micrometer, believe you me! It is a standard, run-of-the-mill good quality 1970s analog micrometer, and so far I have yet to see one without the vernier.

 

[High Binder]

Precisely,no pun intended, with the caveat that they can still (theoretically) measure longer travel lengths, but at the sacrifice of a LOT of turns on the barrel of the mic (literally 10 times the turns) but for these uses they don't typically need the travel length so that would be a more rare mic. But yeah, it's pretty amazing what modern tooling and techniques is producing these days. How'd you like to be the guy at the cal/cert lab tying to make sure they're accurate hahaha. Or worse the poor bastard that's producing the calibration equipment.

Great pun though ^^

LOL, being a cert tech for a lot of this stuff would suck. I remember taking in tools to be re-calibrated and just seeing walls of wacky ass tools/jo-blocks/computers/etc. and they still sent out a ton of things to be calibrated by specialty shops and that was at a major manufacturer everyone has heard of. I can't imagine being a tech at a small job shop, your standards would probably be way out of spec after a while.

 

[Petrov]

I used the analog model with resolution of .0001" so when I say .00015" I am guestimating the last number rougly ased on the position of the has mark.

 

[High Binder]

I used the analog model with resolution of .0001" so when I say .00015" I am guestimating the last number rougly ased on the position of the has mark.

Being that that is the case, you're way over thinking it. If you can get that kind of consistency from a neck turning tool you're already a god. And while not to beat a dead horse please bear in mind that .0001 is 2.54 microns and only some of the finest surface grinders/etc. can hold that kind of tolerance... For reference, a human hair is .003 or 75 microns (i.e. 30 times bigger than what you're claiming) so the likely hood of you holding a 2.54micron Tol. is pretty unbelievable because as mentioned above you'd have to be using a very fine lathe or some kind of highly modified centerless grinder, it's just not going to happen from a hand tool. This is why everybody keeps pushing you toward the thou .001" measurement.

In visual terms your necks would look like mirrors...

 

[Assault116]

!

The photo you posted of the analog micrometer ad shows .001" graduations, yet +/-.0001" resolution, and that (I would logically assume) is made possible by a vernier scale. There's no super tooling involved. All that is involved is making a normal quality micrometer with no unreasonable backlash and marking a vernier scale in the right place. Heck, the one-inch micrometer I have always used and I am now holding was bought by my Dad in the 1970s, and it has the .0001" vernier, and it is a ...hold on to your hat......Sears Craftsman tool. My Dad didn't pay some exhorbitant amount for this micrometer, believe you me! It is a standard, run-of-the-mill good quality 1970s analog micrometer, and so far I have yet to see one without the vernier.

OK maybe I should have qualified my previous statement by saying a mic that can accurately and repeatably measure to .0001.

As to the pic I posted, and the spec you're referring to, it's Accuracy, not resolution, there's a difference, There's a couple different ones in that picture. For instance, the 103-127 has .001 graduations, repeatable (read accuracy) to .0001 there's no 1/10,000th's vernier scale on them. Where as the 103-135 has graduations to .0001 with the same accuracy .0001 Just because it's repeatable to the same level doesn't necessarily mean it's got the scale to do it either.

I know exactly what you're talking about with a vernier scale, it's just that to get a quality unit that can accurately and repeatedly measure to that level was not cheap to produce. That "unreasonable backlash" is what kills 99% of those mics. the average human hair is .003" diameter, now consider for a mic to measure 1/10,0000th accurately, it' needs to be able to measure the thickness of that hair split into 30 thicknesses. ie there can be NO backlash. A mic that could accurately and repeatedly measure to 1/10,000th isn't cheap today let alone when it was harder to produce it.

And quite honestly, I've handled MANY Craftsman mics, and they'll never make certification, you might as well call a C-clamp a mic.

 

[Assault116]

I used the analog model with resolution of .0001" so when I say .00015" I am guestimating the last number rougly ased on the position of the has mark.

You're good, no need to worry about a half of 1/1000th in that application, let alone half of 1/10,000th

 

[OF&B]

Hey guys what is acceptable case neck thickness after neck turning?
I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

Good job, but you might be over doing it.

I look to cut 60-80% of the neck. Anything that gets trimmed more or less than that gets tossed. Anything that shows a lot of variation along the neck gets tossed. I don't think these things help uniform the neck tension anymore, but the necks give some idea about how uniform the rest of the case is.

For measurement, I use a Chinese tubing mike I bought 10-15 years ago for $35. It has the vernier scale, but I usually just estimate between the .001 marks to quarter thousandths. I have 3 cheaper neck turning tools that I leave set up in 223, 308, and 264. Plus one for guest calibers.

 

[Petrov]

Being that that is the case, you're way over thinking it. If you can get that kind of consistency from a neck turning tool you're already a god. And while not to beat a dead horse please bear in mind that .0001 is 2.54 microns and only some of the finest surface grinders/etc. can hold that kind of tolerance... For reference, a human hair is .003 or 75 microns (i.e. 30 times bigger than what you're claiming) so the likely hood of you holding a 2.54micron Tol. is pretty unbelievable because as mentioned above you'd have to be using a very fine lathe or some kind of highly modified centerless grinder, it's just not going to happen from a hand tool. This is why everybody keeps pushing you toward the thou .001" measurement.

In visual terms your necks would look like mirrors...

It is a 99 dollar micrometer, I think it is made in china plus I could be doing something wrong.
I am using the PMA neck turning tool.

 

[captcoop]

I'm in the business of machining . I can promise you five people measuring the same ( whatever it is) and there will be small variations in everyone's numbers. If something is getting measured to the half thou or less. Typically in a machine shop, the person that measures (x, or y) cuts x or y.

 

[High Binder]

It is a 99 dollar micrometer, I think it is made in china plus I could be doing something wrong.
I am using the PMA neck turning tool.

You might just consider checking how your reading it, or it could be mislabeled or something because your numbers, as you've seen from everyone posting here are simply unreal. To test your mic: pull out one of your hairs and check its OD, it should be around .003" and for more frame of reference, there are viruses and bacteria that are 2 microns (your readings). 1/10,000 is insanely small. I worked in a very big machine shop for a huge international company and I don't think we ever had anything call out a tol. of what you're saying. I think my all time closest tol. was -.002mm to +.007mm and that is pretty dang hard to achieve even with CNC machines.

 

[High Binder]

I'm in the business of machining . I can promise you five people measuring the same ( whatever it is) and there will be small variations in everyone's numbers. If something is getting measured to the half thou or less. Typically in a machine shop, the person that measures (x, or y) cuts x or y.

Check it 'till its good.

 

[Petrov]

You might just consider checking how your reading it, or it could be mislabeled or something because your numbers, as you've seen from everyone posting here are simply unreal. To test your mic: pull out one of your hairs and check its OD, it should be around .003" and for more frame of reference, there are viruses and bacteria that are 2 microns (your readings). 1/10,000 is insanely small. I worked in a very big machine shop for a huge international company and I don't think we ever had anything call out a tol. of what you're saying. I think my all time closest tol. was -.002mm to +.007mm and that is pretty dang hard to achieve even with CNC machines.

Is there a proper procedure? I kinda just looked up a you tube video of it and have a rough understanding, I think..

 

[High Binder]

Is there a proper procedure? I kinda just looked up a you tube video of it and have a rough understanding, I think..

Well the best thing to do would be to use a standard that you know the size of and then check it with your mic and see if your mic reads what the standard is. So I my example from above we know that your hair should measure around .003" in diameter so if you pull out one of your hairs and measure it, that is your standard. You could use anything that you know the size but a hair is readily accessible. You could measure the OD of a bullet (.338/.308) or even the width of the necks on your brass (around .015").


I could post some pictures of the process if it would help you?

 

[mdmp5]

The problem with trying to get a resolution of .0001 is that the pressure exerted by the mic on the surface being measured can cause variation. If you measure to the lightest contact, there is uncertainty whether you are fully engaged in the measurement. If you add more pressure, you are engaged, but now you are risking tiny deformity which will give you a smaller reading. If you measure the same object repeatedly and try for .0001 resolution, you will get different readings, and then you have to make the call of which reading is the right one.

 

[M40_A1]

I used the analog model with resolution of .0001" so when I say .00015" I am guestimating the last number rougly ased on the position of the has mark.

It's hard enough to figure out which line is most closely lined up to get to .0001". Trying to subdivide that is beyond the capability of the tool.

The problem with trying to get a resolution of .0001 is that the pressure exerted by the mic on the surface being measured can cause variation....If you measure the same object repeatedly and try for .0001 resolution, you will get different readings, and then you have to make the call of which reading is the right one.

That is what the ratchet stop is for. You're right, though, on measuring objects that have "give". I can measure a steel pin with my craftsman "c-clamp"(LOL) micrometer repeatedly and get the same reading to .0001" (I'm sure Craftsman's quality has changed through the years). As for the accuracy of that reading, I cannot say. But, it should be accurate enough for determining differences of close measurements.

Holy cow, High Binder! .002mm is like .000079"! .0001" seems BIG now!

 

[mdmp5]

It's hard enough to figure out which line is most closely lined up to get to .0001". Trying to subdivide that is beyond the capability of the tool.



That is what the ratchet stop is for. You're right, though, on measuring objects that have "give". I can measure a steel pin with my craftsman "c-clamp"(LOL) micrometer repeatedly and get the same reading to .0001" (I'm sure Craftsman's quality has changed through the years). As for the accuracy of that reading, I cannot say. But, it should be accurate enough for determining differences of close measurements.

Holy cow, High Binder! .002mm is like .000079"! .0001" seems BIG now!

The ratchet stop is indeed a good amenity, but it still does impart additional pressure after engagement. I have the Mitutoyo mic listed above. I really like it for measuring neck tension and neck diameter. I try to engage the neck without clicking the ratchet. Measuring curved or oblong surfaces with flat heads can be challenging, but I do my best, and while I want to get it to the nearest .0001", I have to realize that I am not building a fusion bomb here; it's just ammo.

 

[High Binder]

Holy cow, High Binder! .002mm is like .000079"! .0001" seems BIG now!

Yep. In the machining world we actually refer to such numbers in terms of millionths of an inch. We're getting down into the length of radio waves and sizes viruses. Totally unrealistic numbers for shooting purposes.

 

[Duke1969]

Hey guys what is acceptable case neck thickness after neck turning?
I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

Hey Petrov. If you are really getting those numbers then that is awesome. Somehow the question you posted here sparked a debate over micrometers. So to address your question let me chime in on what i am seeing. I'm getting 0.00035" to 0.00050" neck wall thickness deviation (12 points of measurment using thickest minus thinest measurements) using a combination of FLD set to SAAMI specs, expander dies from 21st Century Reloading, Forester Original Trimmer with reamer attachment (for inside neck turning) & a outside neck turner. This is about as good as someone can get in my opinion without purchasing a very expensive IDOD neck turning lathe unit for $3500.00 from FClass products, which is about the only alternative one has to inside neck turning that I am aware of. And well I'm not at the point in my shooting that I feel I need more precise neck wall thickness deviation that would require me to purchase a unit like the IDOD to go to that next level, I am happy with the current much much cheaper setup. Time consuming, yes, but it works for now. One key note of advice, be carefull to how much you remove from the wall as too much will become unsafe. For what I'm shooting currently I do not keep any brass that is below 0.012" in a .308. Some guys like Eric Cortina has indicated he likes 0.014. Best of luck and tight groups.

Duke

 

[supercorndogs]

Finally after a decade someone answered the correct question. I bet Petrov is dancing with glee. Hasn't visited the sight in two years but maybe this will lure him back.

 

[Alan Warner]

Hey guys what is acceptable case neck thickness after neck turning?
I am getting Getting 0.0001" to 0.00015" of variation sometimes in neck wall thickness.

Your doing fine if you trust your feel. I turn ID and OD in one set up on a Hardinge cnc with a spark out pass on both. .0002 max wall variation is acceptable for me. Tool wear, and the amount of material removed can impact results. Thus the two passes.
Alan
FYI
I use an analog indicating mic with a Deltronics pin to run a check on the mic as I grind dies inserts. I hold the ground Od's to minus 50 mil to minus a tenth. The honed housing is nominal diameter plus 50 mil to plus a tenth. Any less and part roundness makes assembly a pia. Insert roundness off my grinder is 10 to 20 mill. Depends on wheel dress condition. Some of the inserts are up to 2.5 inches long. I run the shorter inserts a little closer.

 

[Duke1969]

Finally after a decade someone answered the correct question. I bet Petrov is dancing with glee. Hasn't visited the sight in two years but maybe this will lure him back.

Anyone ever tell you..oh wait I'm sure your mother mentioned it last when she was @#$% my @#$@.....

 

[Duke1969]

Supercorndogs.... I looked at a lot of your posts... most have nothing to do with reloading or guns... most are just you being a absolute troll online. If that's your thing... well good on you ... look at you go ...your trolling. Now if your done being a little bitch could you please step aside and let the grown ups here have a conversation.

 

[supercorndogs]

Supercorndogs.... I looked at a lot of your posts... most have nothing to do with reloading or guns... most are just you being a absolute troll online. If that's your thing... well good on you ... look at you go ...your trolling. Now if your done being a little bitch could you please step aside and let the grown ups here have a conversation.

Your 3 posts in this thread from 2014 have been a real treasure trove of information. Thanks for taking the time to fill us in. I am sure everyone will be super exited to find out you are here now. Especially Petrov. Waited 10 damn years for a real true grown up to answer his question.

 

[Duke1969]

You're a real class act SUPERCORNDOGS... you offered such a nice welcome to the neighborhood. It surprises me after all these years your still allowed on here. I've seen quite a few of your derogatory comments from the past, and what i gather from them is your just a bully. Ive dealt with people like you many times in my life and there is always one thing that all bullys have in common, you're actually cowards when it comes to step up and put your mouth on the line. If this forum allows a piece of shit like you to propagate on here I think I'd sooner go somewhere else. You have fun with this ... I'm sure it gives you some sort of fulfilment in life being a cunt. It is to bad we couldn't have done this face to face... I would have enjoyed that... I like fucking up bullies like you.

 

[memilanuk]

Dude, let it go. You did a dumb thing - necro posting - and got called on it. Let it go. All you're doing is feeding the troll(s) / amusing the inmates. Yapping like you're all righteous billy-bada$$ just makes you look even dumber.

 

[spife7980]

You're a real class act SUPERCORNDOGS... you offered such a nice welcome to the neighborhood. It surprises me after all these years your still allowed on here. I've seen quite a few of your derogatory comments from the past, and what i gather from them is your just a bully. Ive dealt with people like you many times in my life and there is always one thing that all bullys have in common, you're actually cowards when it comes to step up and put your mouth on the line. If this forum allows a piece of shit like you to propagate on here I think I'd sooner go somewhere else. You have fun with this ... I'm sure it gives you some sort of fulfilment in life being a cunt. It is to bad we couldn't have done this face to face... I would have enjoyed that... I like fucking up bullies like you.

Shut up faggot