# Questions about standards (measuring rods) for micrometers



## erikmannie (Mar 7, 2020)

Regarding measuring rods for outside micrometers, my questions are:

(1) to what degree do you trust import measuring rods?,
2) do you zero your micrometer before using it?, and
(3) should I be concerned about buying used measuring rods?

For my imperial mikes, I have Shars standards and Shars gage blocks. 

For my metric mikes, I bought used Starrett and Mitutoyo standards.

As far as what tolerance I am shooting for, it doesn’t actually matter, BUT I do take my hobby seriously and I shoot for .001” or better. I fail more often than I succeed. I am striving to be able to work to .0003” one day; like I said, it will probably never have any practical application because most of what I do is just an exercise.

I make no effort for temperature control, but I do make an effort to clean the surfaces of oil before I take measurements. That should give you an idea of what precision I am aiming for. For myself, I consider anything much over a thou out to be a failure (or should I say a learning experience?).


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## BrentH (Mar 7, 2020)

Well, 


If the "Standard" I have checks out with the same results on a variety of measuring tools I consider it to be just that - A good standard.

I check my micrometers out periodically or when the project needs to be very accurate.   We had a company working for us and they would only use their own micrometers and they had to be ISO 9000 certified.  They flew them in from Germany in a large crate....These are the ones we will use as they were all calibrated ...they said....WTF - you just flew them overseas in a large crate how can they be any better than the one I have here tested against a known standard?

For measuring accurately on the lathe or milling project that is subject to getting heated during the machining process you should allow things to cool to ambient, take a measure and then cut to final dimension - measuring hot can change a lot!

Check your "used rods" against some reliable tools you have.  Most measuring rods will not see significant action to result in damage.  I would see no reason not to trust them -

If possible use the same instruments for your project so you may not be 100% bang on if someone else measured with a different tool but your fits should still be on the money.


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## erikmannie (Mar 7, 2020)

BrentH said:


> Well,
> 
> 
> If the "Standard" I have checks out with the same results on a variety of measuring tools I consider it to be just that - A good standard.
> ...



A lot of good points there. I am very guilty of measuring things that are pretty warmed up, as what you recommended had never occurred to me.

Nor had it occurred to me to test a measuring rod by using it in two different micrometers and comparing those results. In a perfect world, I would have full confidence in the measuring rod and use that as the standard (as is it’s definition).

I will very often use a few different instruments to measure something. For some reason, I always consider the Starrett mike to have given the correct measurement, with the Shars mike serving as the second opinion, and the calipers to be the sanity check.

I do much the same with the measuring rods and gage blocks. I like a second opinion. 

We can easily work to .005”, but rarely to .0001”, so that mere 5 thou range is where we move from pretty easy to extremely difficult.


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## middle.road (Mar 7, 2020)

Hitting .001 in an non-controlled shop is going to be tough.
.0003 without climate control and other controls? That's going to be even tougher.


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## erikmannie (Mar 7, 2020)

middle.road said:


> Hitting .001 in an non-controlled shop is going to be tough.
> .0003 without climate control and other controls? That's going to be even tougher.



This might explain my near 100% failure rate.


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## benmychree (Mar 7, 2020)

2) do you zero your micrometer before using it?, 

You get close to zero and take a measurement on the rod with a very careful feel, and then reset the mike to zero if necessary.  I find it difficult to use gage blocks to set mikes because it is difficult to avoid slightly off perpendicularity with the mike's anvil and spindle.  The setting standard rods have radiused ends, avoiding the problem.


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## middle.road (Mar 7, 2020)

erikmannie said:


> This might explain my near 100% failure rate.


It's not 'failure' when you try.


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## westerner (Mar 7, 2020)

erikmannie said:


> We can easily work to .005”, but rarely to .0001”,


You do realize that is a 50 to 1 relationship, yes? 
If you are trying to secure a NASA contract, those numbers may be relevant. I have several posts here about chasing precision that is not required. I am just a hack, but what difference does .0009 make? Or .005? What are you building?  
I surely appreciate the desire to "hit your numbers". I have accepted the fact that the numbers I can hit are big 3 digit ones. I will not obsess over 4 digits at all.


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## mikey (Mar 7, 2020)

erikmannie said:


> Regarding measuring rods for outside micrometers, my questions are:
> 
> (1) to what degree do you trust import measuring rods?,
> 2) do you zero your micrometer before using it?, and
> (3) should I be concerned about buying used measuring rods?



1) I use Mitutoyo mic standards and they're pretty okay for a quick check but they are not good enough to calibrate a mic.
2) I always clean the mic faces with Kim Wipes and gently close them to make sure the mic is zeroed before use. I could probably dispense with this because the mic always reads zero.
3) Mic standards (rods) are not used often so if you buy good ones used, they will probably be okay. If you really want to know if they are accurate, send them to a calibration lab and have them report their lengths so you know what they really are. Because a mic standard is marked 1" or 2" or whatever, it doesn't mean that is the actual length to a millionth of an inch. If you must know how long they are, have them measured by a lab. You just have to keep in mind that that rod was measured in a lab and its length may/will be different in your shop and in your hands ... but it will be damned close.

Your unasked question is actually about trust. Can you trust the rods to be accurate enough to give you confidence in your measuring tool? This is not about the level of work you can actually do; it is about trusting the readings you get. 

Just so you know, calibrating your tools is a personal choice. Calibration refers to the act of evaluating and adjusting the precision and accuracy of measurement equipment. This is different from Certifying it, which is done by a lab; they will tell you if the instrument falls within the acceptable standards for that tool. Certification is done in a controlled environment by techs who know what they're doing, using equipment that is far more accurate than most of us own. 

I calibrate my own mics and calipers. I now use a Mitutoyo Cerastone Grade A set that is specifically made for calibrating micrometers and is accurate to between 4-6 millionths of an inch. I follow the standard procedures to check my tools and this gives me enough confidence in them to trust them. I do not need to certify them or have them certified; I just need to know I can trust their readings. How accurate I can work is a separate thing.


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## erikmannie (Mar 7, 2020)

westerner said:


> You do realize that is a 50 to 1 relationship, yes?
> If you are trying to secure a NASA contract, those numbers may be relevant. I have several posts here about chasing precision that is not required. I am just a hack, but what difference does .0009 make? Or .005? What are you building?
> I surely appreciate the desire to "hit your numbers". I have accepted the fact that the numbers I can hit are big 3 digit ones. I will not obsess over 4 digits at all.



I get my money from my job which has nothing to do with machining, so all of the work in my shop is hobby stuff. I have the most fun when I am challenged; the more challenging, the more fun. The best day is when I fail because I make sure to learn something from it.

Generally, after I make something it goes out on the “metal” shelves which is a euphemism for the scrap area.

In machining school, they recommended to shoot for a thou tolerance and expect to fall short. They also said that if a tolerance is not written on the drawing, then assume .005”. 

With the understanding that I am just having fun in the shop, my target tolerance was chosen as .001” for now because I don’t think there will ever be any temperature control out there. My best case scenario of .0003” is probably optimistic, considering the lack of a controlled climate.

So the .0003”-.001” tolerance is just a goal and not required by any means. To be honest, I would be very pleased if I hit a thou.


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## mmcmdl (Mar 7, 2020)

I very rarely have to hold anything under .0005 now unless it's bearing related . If I make something for myself , I design the G-job so it doesn't have to be a close tolerance . For my "work" these days , I usually have to hold +/-  half a broomstick .  Best bet for learning , always aim for your nominal dimension . Shoot for the middle .


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## middle.road (Mar 7, 2020)

"_I am just having fun in the shop_" -- That is the main thing. Be it whatever, as long as you're having fun doing it.
Try making up some of the mechanical puzzles that are out there. Good experience and fun to create.



erikmannie said:


> I get my money from my job which has nothing to do with machining, so all of the work in my shop is hobby stuff. I have the most fun when I am challenged; the more challenging, the more fun. The best day is when I fail because I make sure to learn something from it.
> Generally, after I make something it goes out on the “metal” shelves which is a euphemism for the scrap area.
> In machining school, they recommended to shoot for a thou tolerance and expect to fall short. They also said that if a tolerance is not written on the drawing, then assume .005”.
> Understanding that _*I am just having fun in the shop*_, my target tolerance was chosen as .001” for now because I don’t think there will ever be any temperature control out there. My best case scenario of .0003” is probably optimistic, considering the lack of a controlled climate.
> ...


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## mmcmdl (Mar 7, 2020)

erikmannie said:


> In machining school, they recommended to shoot for a thou tolerance and expect to fall short. They also said that if a tolerance is not written on the drawing, then assume .005”.



Form , fit and function . Don't mill if a saw cut is adequate . Finish specs also determine what is needed . Never give a customer " more than what is needed " , it'll quickly eat up your time and profit .


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## erikmannie (Mar 7, 2020)

mikey said:


> 1) I use Mitutoyo mic standards and they're pretty okay for a quick check but they are not good enough to calibrate a mic.
> 2) I always clean the mic faces with Kim Wipes and gently close them to make sure the mic is zeroed before use. I could probably dispense with this because the mic always reads zero.
> 3) Mic standards (rods) are not used often so if you buy good ones used, they will probably be okay. If you really want to know if they are accurate, send them to a calibration lab and have them report their lengths so you know what they really are. Because a mic standard is marked 1" or 2" or whatever, it doesn't mean that is the actual length to a millionth of an inch. If you must know how long they are, have them measured by a lab. You just have to keep in mind that that rod was measured in a lab and its length may/will be different in your shop and in your hands ... but it will be damned close.
> 
> ...



I don’t know if I’m doing it right, but I clean the anvils and check zero on a 0-1” or 0-25mm mike before an important measurement (as opposed to roughing). I use a standard on a, e.g., 1-2” or 25-50mm mike in the same manner. Does anybody ever just take a large mike out of the box, clean the anvils and measure the work? Maybe I am wasting time by using a measuring rod to check the zero each day.

I don’t think I would have the money for any calibration services.


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## erikmannie (Mar 7, 2020)

I give a lot of credit to you machinists who have customers. I get enough of that at work. 

In my shop, I am too selfish about my creative freedom to allow in others who might alter the path that I want to take. Again, I get more than enough of that at work.

Having said that, I retire in a little over 11 years, and I might change my tune when I need customers’ money.


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## mmcmdl (Mar 7, 2020)

No need to check everyday Eric . Even in DOD shops , they only require tools to be calibrated every 6 months . Clean your anvils when the job is finished , just for storing tools .


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## mmcmdl (Mar 7, 2020)

erikmannie said:


> In my shop, I am too selfish about my creative freedom to allow anyone else to restrict what I do. Again, I get more than enough of that at work.


Me too ! I haven't had a customer in 25 years .  I send them to a machine shop . I got tired of spending days making parts for neighbors that they could purchase for a buck . I had plenty of those type of jobs .


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## erikmannie (Mar 7, 2020)

mmcmdl said:


> Me too ! I haven't had a customer in 25 years .  I send them to a machine shop . I got tired of spending days making parts for neighbors that they could purchase for a buck . I had plenty of those type of jobs .



Customers can be great, but they can also be very annoying! 

I stopped taking work when a few people haggled on the price. They did not appreciate the investment in time, money and effort that I had made. This is why I have so much respect for people who do paid work. They have to put up with a lot of foolishness.


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## mmcmdl (Mar 7, 2020)

erikmannie said:


> Customers can be great, but they can also be very annoying!



Machining is annoying when doing it for money , that's why my shop has been " shut down " for many years . My worst customer was my neighbor with his Gravely addiction !


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## mikey (Mar 7, 2020)

mmcmdl said:


> No need to check everyday Eric . Even in DOD shops , they only require tools to be calibrated every 6 months . Clean your anvils when the job is finished , just for storing tools .



I agree with Dave. Also, make sure the faces of your 0-1" mic are NOT touching when you store it.


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## mmcmdl (Mar 7, 2020)

mikey said:


> Also, make sure the faces of your 0-1" mic are NOT touching when you store it.



Yes , that is a no no , same with calipers .


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## Boswell (Mar 7, 2020)

mmcmdl said:


> Yes , that is a no no , same with calipers


ooo I did not know that.  thanks for the tip.


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## erikmannie (Mar 7, 2020)

mmcmdl said:


> Yes , that is a no no , same with calipers .


Yes, I always leave them open a little.

So how often are you guys breaking out your micrometer standards? 

How often are you guys checking the zeroes on the outside micrometers larger than 1” (or 25mm)?


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## mmcmdl (Mar 7, 2020)

Never .  No need to .


erikmannie said:


> So how often are you guys breaking out your micrometer standards?
> 
> How often are you guys checking the zeroes on your outside micrometers?


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## erikmannie (Mar 7, 2020)

mikey said:


> ...2) I always clean the mic faces with Kim Wipes and gently close them to make sure the mic is zeroed before use. I could probably dispense with this because the mic always reads zero.
> 3) Mic standards (rods) are not used often so if you buy good ones used, they will probably be okay...



So we all know how to do this with  0-1” mike, but if it is 1-2”, 25-50mm, and up then my understanding is that the purpose of the measuring rod is to “make sure the mike is zeroed before use” as mentioned in (2) above.

For a larger micrometer, I would not know of a way to make sure the mike is zeroed before use without using a standard. I have always thought that one needed a standard to check the zero on a larger mike.


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## rwm (Mar 7, 2020)

I didn't even know you could have 4 digits after a decimal point?
R


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## erikmannie (Mar 7, 2020)

rwm said:


> I didn't even know you could have 4 digits after a decimal point?
> R



Not for the metric folks. Not too many people posting about .0001mm as each one of these units is 39.37 millionths of an inch.

Everybody here probably knows this, but I wondered what metric people machined to (because I was only hearing about thousandths). Someone on here said that they machine to .1mm for most stuff, and to .01mm for really precise stuff. So this is basically equivalent to machining to .004” for most stuff, and down to .0004” for really precise stuff. This makes sense.


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## mmcmdl (Mar 7, 2020)

erikmannie said:


> For a larger micrometer, I would not know of a way to make sure the mike is zeroed before use without using a standard. I have always thought that one needed a standard to check the zero on a larger mike.



Yes , you do need a standard or gage blocks to initially set larger mics to zero . Then check them every so often .


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## erikmannie (Mar 7, 2020)

mmcmdl said:


> Yes , you do need a standard or gage blocks to initially set larger mics to zero . Then check them every so often .



Thank you for your prompt reply. I was very curious about that. I had been doing it every day, but I will loosen up a bit and have more faith in the workmanship of the equipment.

The Starretts are fine, BUT the first micrometers that I got were all Shars, and they won’t even return to zero after measuring a standard. So I got off to a rocky start as far as having faith in the metrology equipment.


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## MontanaLon (Mar 7, 2020)

mikey said:


> I agree with Dave. Also, make sure the faces of your 0-1" mic are NOT touching when you store it.


And it goes without saying if your faces ever touch on a 1-2" or larger micrometer, any measurements are to be viewed with suspicion. 

Really all the standards that come with the mics do is give you a zero point. They are pretty accurate and you can usually prove it to yourself by starting with your 0-1" and zero it. Then open it up and put the 1-2" standard in which will measure 1". I have found even the cheap harbor freight standards are accurate below 0.0001. You just keep repeating using the next size up standard to measure the max after checking zero.

As 3450 said, dropping them or getting them tangled up in work is really the only way to get them out of calibration. I am sure measuring abrasives would be pretty hard on them as well, but how often do we do that?


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## mmcmdl (Mar 7, 2020)

MontanaLon said:


> And it goes without saying if your faces ever touch on a 1-2" or larger micrometer, any measurements are to be viewed with suspicion.



Now that is just plain funny !


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## erikmannie (Mar 7, 2020)

MontanaLon said:


> ...if your faces ever touch on a 1-2" or larger micrometer...



If you are talking about the faces of the anvils, how would this happen? When the head is dialed in all the way, the anvils are almost an inch apart.


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## mmcmdl (Mar 7, 2020)

erikmannie said:


> If you are talking about the faces of the anvils, how would this happen? When the head is dialed in all the way, the anvils are almost an inch apart.


You're learning !  ( that was sarcasm )


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## MontanaLon (Mar 7, 2020)

erikmannie said:


> If you are talking about the faces of the anvils, how would this happen? When the head is dialed in all the way, the anvils are almost an inch apart.





mmcmdl said:


> You're learning !  ( that was sarcasm )


Yes, sarcasm and snark.


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## BrentH (Mar 8, 2020)

Remember this, some other supplier has introduced an accurate measuring device based on the testicular hair of a Pomeranian silky underpants  ball pouch of a seven thousand year  dinosaur louse  found in a fossil ....................... accurate to 0.00000001


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## mikey (Mar 8, 2020)

One thing that most hobby guys don't check is parallelism of the faces. This is one of the first steps in calibrating a mic but is often missed, and this is not good because hobby guys often buy used mics who's faces may be worn. You can still zero a mic with a worn face or check with a mic standard and be convinced the mic is accurate but it may not be, depending on how the mic contacts the work.

In order to check parallelism, the "recommended" way is to use an optical flat and a monochromatic light but not many of us own that kind of light source. An alternative method is to check the anvil and spindle with a gauge block. You check the edges in 4 places (12, 3, 6 and 9 O'clock) and the center with a gauge block. If all 5 read the same then the faces must be parallel.

The other thing worth mentioning is that a mic is always checked while being held in a micrometer stand, not your hand, and the gauge blocks or mic standard is handled either briefly or preferably with tongs. 

Much is made about being in a temperature-controlled environment and all that but we are not certifying our tools. We are simply calibrating them to be sure they are accurate and to be sure that zero means zero.

Erik, there is nothing wrong with wanting to know if your tools read what they are supposed to read. You may take some heat for it, with the implication being that you're just a hobby guy so why be so anal about it? It isn't like you're making parts for NASA, right? Well, I'm a hobby guy and on occasion have to make parts to very tight tolerances. If I can't reliably measure it then I can't cut it.  

Even hobby guys need to be accurate at times so ignore the naysayers and learn.


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## erikmannie (Mar 8, 2020)

mikey said:


> One thing that most hobby guys don't check is parallelism of the faces. This is one of the first steps in calibrating a mic but is often missed, and this is not good because hobby guys often buy used mics who's faces may be worn. You can still zero a mic with a worn face or check with a mic standard and be convinced the mic is accurate but it may not be, depending on how the mic contacts the work.
> 
> In order to check parallelism, the "recommended" way is to use an optical flat and a monochromatic light but not many of us own that kind of light source. An alternative method is to check the anvil and spindle with a gauge block. You check the edges in 4 places (12, 3, 6 and 9 O'clock) and the center with a gauge block. If all 5 read the same then the faces must be parallel.
> 
> ...



More very helpful information that I was not aware of.

Regarding my desire to be so fastidious, I try to do each step as carefully as I am able because some steps along the way may come up short. I have made a few projects which turned out very nice; nobody other than myself would see the imperfections, and sometimes I even forget about the imperfections after awhile.


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## MontanaLon (Mar 8, 2020)

mikey said:


> Erik, there is nothing wrong with wanting to know if your tools read what they are supposed to read. You may take some heat for it, with the implication being that you're just a hobby guy so why be so anal about it? It isn't like you're making parts for NASA, right? Well, I'm a hobby guy and on occasion have to make parts to very tight tolerances. If I can't reliably measure it then I can't cut it.
> 
> Even hobby guys need to be accurate at times so ignore the naysayers and learn.


It is very cool to hit tight tolerances as a hobbyist. I mean nothing is cooler than the popping sound made when you create a piston for a tube you have made so perfect that it will create a vacuum when they are put together and pulled apart. Anyone can hit that with an o-ring but to do it without one is a feat. The simple truth is you really can't do it without accurate measuring tools.


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## erikmannie (Mar 8, 2020)

MontanaLon said:


> It is very cool to hit tight tolerances as a hobbyist. I mean nothing is cooler than the popping sound made when you create a piston for a tube you have made so perfect that it will create a vacuum when they are put together and pulled apart. Anyone can hit that with an o-ring but to do it without one is a feat. The simple truth is you really can't do it without accurate measuring tools.



Well, that is certainly better than doing a mediocre job. If I can get a good result, I am happy to spend the time, money and effort. I often run out of all three of these commodities along the way for larger projects. 35 years ago, a successful chef told me “Yo...nunca tengo prisa” (“I...am never in a hurry”). This guy was as stubborn as a mule, but I thought those were wise words.


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## mikey (Mar 8, 2020)

erikmannie said:


> Regarding my desire to be so fastidious, I try to do each step as carefully as I am able because some steps along the way may come up short. I have made a few projects which turned out very nice; nobody other than myself would see the imperfections, and sometimes I even forget about the imperfections after awhile.



As you mature in this hobby, you will find that your work will get better and better IF you care and if you learn from your mistakes. 

The next thing you'll question is: Just how square is square and how do I know?


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## mmcmdl (Mar 8, 2020)

How square is square and how do you know ?   ( somebody had to ask )


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## mikey (Mar 8, 2020)

mmcmdl said:


> How square is square and how do you know ?   ( somebody had to ask )



I dunno', but the question will arise as sure as death and taxes ...


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## erikmannie (Mar 9, 2020)

Here’s an story about an eBay purchase I made for a 100mm measuring rod.

I bought a used Starrett 100mm measuring rod for $19. A couple of days later, the Seller sent me a message saying that it was mismarked “100mm” at the Starrett factory, and that it actually measured 125mm. He asked if I still wanted it, but I already have a 125mm standard.

Anyway, I don’t believe that Starrett would have mismarked it at the factory. I looked for another one for a good price, but there are none out there at this point.


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## MrWhoopee (Mar 14, 2020)

erikmannie said:


> Maybe I am wasting time by using a measuring rod to check the zero each day.



Checking your mics daily?!!! How often do you have to re-zero them?

I continue to be amazed at how far down in the weeds hobbyists will get about precision for which there is no need. I guess it comes from not knowing what is reasonably expected in the real world.  If you have to hit .001 or less, by all means get out the standard and be sure of your zero. Otherwise, you're just being EC. (That's Excessive Compulsive, the next step beyond Obsessive Compulsive.)


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## erikmannie (Mar 14, 2020)

MrWhoopee said:


> Checking your mics daily?!!! How often do you have to re-zero them?
> 
> I continue to be amazed at how far down in the weeds hobbyists will get about precision for which there is no need. I guess it comes from not knowing what is reasonably expected in the real world.  If you have to hit .001 or less, by all means get out the standard and be sure of your zero. Otherwise, you're just being EC. (That's Excessive Compulsive, the next step beyond Obsessive Compulsive.)



I have never had to rezero a Starrett. The Shars appear to be hopeless just about every time.

This is the first I’ve heard that practice machining to .001” may be excessive attention to detail. I took machining classes in Oakland, CA, and the turning and milling was to .001”. They also said if the drawing doesn’t list a tolerance, then you can assume .005”.


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## stuarth44 (Mar 14, 2020)

erikmannie said:


> Regarding measuring rods for outside micrometers, my questions are:
> 
> (1) to what degree do you trust import measuring rods?,
> 2) do you zero your micrometer before using it?, and
> ...


i check all mearuring tools by my starrett standards, I  bough a set of mics from ebay, they were far out


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## erikmannie (Mar 14, 2020)

stuarth44 said:


> i check all mearuring tools by my starrett standards, I  bough a set of mics from ebay, they were far out




What brand did you buy on eBay? Are they new or used?


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## stuarth44 (Mar 14, 2020)

erikmannie said:


> What brand did you buy on eBay? Are they new or used?


https://www.ebay.com.au/itm/4pcs-se...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 unbranded Erik


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## MrWhoopee (Mar 14, 2020)

erikmannie said:


> This is the first I’ve heard that practice machining to .001” may be excessive attention to detail. I took machining classes in Oakland, CA, and the turning and milling was to .001”. They also said if the drawing doesn’t list a tolerance, then you can assume .005”.



On most of the drawings we worked from (including the ones I drew), the titleblock (default) tolerances were 
1/x=+/-.015 
.xx=+/-.01
.xxx=+/-.005

These applied to dimensions without a specified tolerance. A specified tolerance of +/- .001 (or less) would not be unusual, but certainly not prevalent.

It is certainly important to be able to achieve tight tolerances, which is why you were taught that way. I would never discourage someone who is learning from trying to do the best he can. It is equally important to understand when close tolerances are unnecessary and not waste time (money) taking the extra cut(s) when the part is already within tolerance. The most valuable machinists are not the ones who hit every number right on the nominal, they are the ones who can produce a good looking part with all of the dimensions within tolerance in the least amount of time. When Fred would find someone worrying a dimension unnecessarily, he would yell "IT FITS AIR!!!"


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## stuarth44 (Mar 14, 2020)

MrWhoopee said:


> On most of the drawings we worked from (including the ones I drew), the titleblock (default) tolerances were
> 1/x=+/-.015
> .xx=+/-.01
> .xxx=+/-.005
> ...


true nuff, when it comes to shrink fot, or you are working in a tool room, close is close enough, but if you aim for 001 and get it,you feel good


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## astjp2 (Jun 18, 2020)

erikmannie said:


> I give a lot of credit to you machinists who have customers. I get enough of that at work.
> 
> In my shop, I am too selfish about my creative freedom to allow in others who might alter the path that I want to take. Again, I get more than enough of that at work.
> 
> Having said that, I retire in a little over 11 years, and I might change my tune when I need customers’ money.


I work on airplanes and for the most part I have good customers but just a couple are bad enough for me to want to get out of business... I used to enjoy it, now it has become a chore that pays the bills.  The ones that are the worst are when you are charging less than most people in my area, I have to travel to them and no matter what, its too much and they nit pick everything you do.  Tim


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## Buffalo21 (Jun 18, 2020)

My great-uncle, always said, “you machine to the tolerance the customer is willing to pay for, the tighter the tolerance, the more it cost”


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## MrWhoopee (Jun 18, 2020)

astjp2 said:


> The ones that are the worst are when you are charging less than most people in my area, I have to travel to them and no matter what, its too much and they nit pick everything you do.  Tim


 
I have fired a few of these. It's the old 80/20 rule, they are 80% of your grief and 20% (or less) of your income.


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## stuarth44 (Jun 18, 2020)

erikmannie said:


> Regarding measuring rods for outside micrometers, my questions are:
> 
> (1) to what degree do you trust import measuring rods?,
> 2) do you zero your micrometer before using it?, and
> ...


bit late here, all my digi verniers are out, according to my Starrett standard and by quite a way too, they are not well known makes but hell!!


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## erikmannie (Jun 18, 2020)

stuarth44 said:


> bit late here, all my digi verniers are out, according to my Starrett standard and by quite a way too, they are not well known makes but hell!!



Well, that’s not good! +1 for dial type (analog) calipers.


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## MrWhoopee (Jun 19, 2020)

stuarth44 said:


> bit late here, all my digi verniers are out, according to my Starrett standard and by quite a way too, they are not well known makes but hell!!



I'm a little confused. Are they digital or vernier, how many and how far out?


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## pontiac428 (Jun 19, 2020)

Something to ponder:  you can never calibrate a micrometer.  A micrometer is linear, or y=mx+b in slope-intercept form.  There ate two terms, m (slope) and b (intercept).  You can adjust the intercept; that is called zeroing, and it's what you do with your standard.  But you cannot change the x/y relationship, that is ground into the threads of the mic barrel.  All you can do is VERIFY calibration with a check standard.  If your mic measures 1.010" over it's range on a 1.000" standard, and 2.040 on a 2" standard, you can't adjust that out, so the caliper would be disposed of.  You can adjust the zero for 1.000 and 2.030, but you can't make that second reading change in any way.

Between micrometers, technique, temperature, and anything else we can think of to control, there will always be issues that skew your measurement off of the true value.  Hence measurement error, error budget factors, and compounding errors that all go into effect when deriving precision and accuracy.  These are the reasons I don't work to 10ths!


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## JRaut (Jun 19, 2020)

I check my mics every couple seasons or so.

My shop is in my basement. Climate control is better than an unheated garage/shed, but it ain't 72* year-round. It gets up to the 80s or so in the summer and down to the 50s or so in the winter.

Sometimes I have to give one or two a little tweak, but never more than a couple tenths' worth.


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## Winegrower (Jun 19, 2020)

astjp2 said:


> I work on airplanes and for the most part I have good customers but just a couple are bad enough for me to want to get out of business... I used to enjoy it, now it has become a chore that pays the bills. The ones that are the worst are when you are charging less than most people in my area, I have to travel to them and no matter what, its too much and they nit pick everything you do. Tim




I have thought for a long time that the biggest problem in aviation are the pilots.


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## stuarth44 (Jun 20, 2020)

MrWhoopee said:


> I'm a little confused. Are they digital or vernier, how many and how far out?


digital verniers, I'd have to check how far out


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## jwmelvin (Jun 20, 2020)

stuarth44 said:


> digital verniers, I'd have to check how far out



I believe the question was intended to reflect that “vernier” is not something that can be digital, as it is a system of indicating by using differentially spaced lines. https://en.m.wikipedia.org/wiki/Vernier_scale

Some people seem to refer to caliper as a vernier, I suppose because early calipers used vernier scales. Thus they refer to a digital vernier when the intended term is likely digital caliper.

I have a pair of vernier calipers and I like that they don’t run out of batteries, though dial calipers have that same advantage while also being quick to read. Micrometers often use a vernier scale to indicate the final decimal place (0.0001” increments for imperial tools). So just saying “a vernier” can be confusing.


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## stuarth44 (Jun 20, 2020)

jwmelvin said:


> I believe the question was intended to reflect that “vernier” is not something that can be digital, as it is a system of indicating by using differentially spaced lines. https://en.m.wikipedia.org/wiki/Vernier_scale
> 
> Some people seem to refer to caliper as a vernier, I suppose because early calipers used vernier scales. Thus they refer to a digital vernier when the intended term is likely digital caliper.
> 
> I have a pair of vernier calipers and I like that they don’t run out of batteries, though dial calipers have that same advantage while also being quick to read. Micrometers often use a vernier scale to indicate the final decimal place (0.0001” increments for imperial tools). So just saying “a vernier” can be confusing.


tes accept that, well then,my digital calipers, will check on variation today


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