What gauge for micrometer

[sutherpride59]

So we all have some tool for measuring our boolits to make sure of this or that but what kind of gauge should be used to calibrate our micrometers and calipers to make sure they are in spec?

[str8wal]

I close them, set to zero, and measure away....

[mdi]

I too just check for "zero", gently. I've been using micrometers off and on since 1968 and rarely found a need to check against "go blocks" (when I was working in a machine shop measuring to .0005" I dropped a mike and needed to check it ). Since I don't use my mikes like a c-clamp I've never had any good micrometers loose accuracy...

[williamwaco]

I check zero then check a 224 and a 308 match grade bullet. I keep the "gauge" bullets forever. This will not tell me if the instrument is dead on accurate but it will tell me if it has changed.

[Ole Joe Clarke]

You can buy standards to set them by. If the micrometer is in good shape, clean the faces of the checking surfaces, gently "zero" them out and adjust if needed. A small spanner wrench is required.

Have a blessed day,

Leon

[W.R.Buchanan]

Typically when calibrating a o-1" mic you would make the adjustment by closing the mic and making the adjustment.

If you are measuring stuff that is closer to 1" then using a 1" standard would be more accurate.

Older micrometers do vary sometimes. Newer quality ones ,,, not so much. Pretty much anything is going to be accurate enough for measuring boolits.

Randy

[country gent]

On 0-1 mics closing to your feel is the prescribed method of checking to see if they are zeroed. On bigger a standard or Jo Block is used same with calipers. We also had to once a year check micks at .025 increments, this showed any anvil wear on the insterments. Calipers were checked thru their range every inch. They were also checked back of jaws and front of jaws for wear. ( the narrow Knife edges wear faster than the backs wider surfaces. ID jaws were checked in rings. The depth measuring surfaces of the jaws were done with Jo blocks same as the depth rod. In the shop measuring tools were checked before use. My 4', 5' and 6' mics went months not being needed. The0-1" and 2" were daily as were the 6" calipers. the 24" calipers again might be in the box for several months between uses. ANother thin is to clean the measuring faces before use and setting.

[NSB]

I worked as a quality manager for a couple of very big companies before retiring. One of my responsibilities during my career was to supervise several metrology labs where there were literally thousands of gages that were in the system. In my experience, it would be rare to find a new set of gages that weren't accurate unless they had been dropped or damaged. Even the cheaper foreign stuff was fairly accurate. The correct way in a manufacturing organization would be to check the gage against known standards (gage blocks, etc) over a range of measurements within the gages design. For actual real world use, setting them to zero by gently wiping and closing them and adjusting to zero will suffice for any needs in the shooting world.

[M-Tecs]

For low usage 0 to 1 mics zeroing at closed is adequate for most applications. When trying to get max accuracy using a gage pin or gage block the same size as you measuring. For over 1" mic standards or gage blocks.

https://www.mscdirect.com/browse/tn/Measuring-Inspecting/Dimensional-Measuring-Tools/Micrometers/Micrometer-Calibration-Standards-Sets/Micrometer-Calibration-Standards?navid=12107823

https://www.mscdirect.com/browse/?navid=12107680&rd=k&searchAhead=true&searchAheadTerm=gage&typahddsp=Gage%20Blocks%2C%20Spacers%20%26%20Balls&hdrsrh=true

https://www.mscdirect.com/browse/lookahead/?searchterm=pin+gauge&rdrct=Gage%20pins

[David2011]

I check zero then check a 224 and a 308 match grade bullet. I keep the "gauge" bullets forever. This will not tell me if the instrument is dead on accurate but it will tell me if it has changed.

I do the same. Commercial bullets are very consistent.

[jimkim]

In a shop I would use a 1.0000" gauge block to verify it at 1", and a 0.1000" block at the low end. If it is correct at zero or with feeler gauges, then that should be good enough for measuring bullets.

Sent from my VS880 using Tapatalk

[Ballistics in Scotland]

It is very rare to need a test standard for something like a 0 - 1in. micrometer. Checking that it reads zero when it is closed down to zero should be fine. I have a larger micrometer with an interchangeable anvil to measure down to zero, and the same applies. The need for a standard comes in with 2 - 3in. and larger, which can't be closed down to zero.

In theory you could just keep a small piece of, say, nominal 1in. ground flat stock which you have measured when the micrometer was new and trusted, marked with the measurement if it was a thousandth or two over or under. But a proper test standard has convex ends, just as if it had been made by drilling through a sphere with a long, thin holesaw. That way it is accurate if it is rocked slightly out of alignment with the axis of the threads, and more important, it is less vulnerable to specs of dust distorting the measurement.

[6bg6ga]

I too just check for "zero", gently. I've been using micrometers off and on since 1968 and rarely found a need to check against "go blocks" (when I was working in a machine shop measuring to .0005" I dropped a mike and needed to check it ). Since I don't use my mikes like a c-clamp I've never had any good micrometers loose accuracy...

The common mistake in checking a mic or vernier is to close it tight or try to use it as a vice in checking something. I was a quality control supervisor for a while and I had a class for new quality control inspectors to teach them the proper use of their mics and calipers. Once taught none of them mishandled their equipment.

My experience with the "older mics" was I never had a problem with them either since they were made very well probably better than some of the suff out there today. I grew up with the old style mics and calipers instead of the direct read out ones.

[barrabruce]

I will check my calipers with my mic to see if the jaws are all good.
Especially the inside diameter end.
Now to really get proper measurements then your tools and test piece should be the same temp. 25 c and all that.
In reality if measure something with a mic I will use the same tool to measure my component.
That way if my tool is a poofteen out then the work will be also ...but they will have the desired fit.
Don't forget its all about feel and a old mic used to measure cutting tools all day with scores in the anvils will feel a lot different than polished surfaces.
My 2 cents worth.

[6bg6ga]

Now that we've covered what not to do I'll touch on the checking part. Its already been mentioned that there are go gauges precision ground blocks. In addition there are also pin gauges that are specific diameters that can be used to check. I wouldn't try to use for example steel or aluminum in different gauges because the tolerance isn't tight enough to use.

[KenT7021]

To clean the jaws on calipers or mic's close them lightly on a clean sheet of paper and pull the paper thru the jaws.

[John Boy]

So we all have some tool for measuring our boolits to make sure of this or that but what kind of gauge should be used to calibrate our micrometers and calipers to make sure they are in spec? Certified pin gages - your choice plus or minus Tolerance: 0.0002"
Even my Harbor Freight calipers are with tolerance ...
205772

[DougGuy]

Standards are pretty easy to get, a lot of micrometers ship with a standard included with the mic. You use the standard to set the mic to the exact length of the standard and this calibrates the mic. I do things a little differently, I like to calibrate the mic as near as I can to the diameter I am going to be using it the most. I have to take a lot of 45 caliber measurements just from the volume of 45 caliber barrels and cylinders I get in for throating so I like to zero my mic at .4520" and call it good.

[DougGuy]

Use a gage pin close to the diameter of the work you most frequently measure. A .452" Z minus pin is actually .4518" where a ZZ minus is .45198" so your mic should be one that reads in .0001" for cylinder, barrel, and boolit work and it should read pretty close to what the pin diameter is when mic'ing a gage pin.

[smokeywolf]

Gage pins are a good choice for a mike standard since they're also a needed tool for checking hole sizes and cylinder alignment and timing.

[bosterr]

Use a gage pin close to the diameter of the work you most frequently measure. A .452" Z minus pin is actually .4518" where a ZZ minus is .45198" so your mic should be one that reads in .0001" for cylinder, barrel, and boolit work and it should read pretty close to what the pin diameter is when mic'ing a gage pin.

I agree with Doug's way of thinking in that I will get a pin gauge at .4000. From Amazon, would I order a .400 go or no go pin if I want EXACTLY .4000?

[DougGuy]

I agree with Doug's way of thinking in that I will get a pin gauge at .4000. From Amazon, would I order a .400 go or no go pin if I want EXACTLY .4000?

Neither. I would wait until Meyer Gage is open and call them and ask before you order, even if you don't order from Meyer they can answer your questions. For the most part they don't make exact sizes because that throws off all references because you can't measure a .400" hole with a .400" pin it simply will not go through the hole so the nearest increment smaller pin is used and if this smaller pin goes through the hole snugly, it is sized with the measurement of the hole the pin will fit into and not the pin itself.

If you want added clearance, you use a plus size gage set, this will insure there is adequate clearance for the stated diameter, so the designated pin will go through the hole.

Does this make any sense? For an exact hole size, you need to have undersized measuring pins so they will fit through the hole to measure it. For an exact size pin or bolt to fit through a hole, the hole must be slightly larger, so they make the plus gages to measure a hole to see if it has clearance for the stated size pin or bolt to go through the hole.

There really isn't much call for exact size gage pins, but I think they make them for calibrating other instruments with, not for checking hole sizes.

[bosterr]

Doug, I'm sorry for not being more clear. Sometime things don't come out like I mean. The only things I ever measure are boolits and lead slugs that I've tapped through the bore of a gun. I'm not a gunsmith although I occasionally pretend to be. I'll never need to know the size of a hole in what I do.

[chuckbuster]

Doug, don't want to offend anyone but
Better check your Tolerance Class Chart and math.
ZZ is +/- .0002 nominal
Z is +/- .0001 nominal
Y, X, XX get into "millionths"
"Master" tolerance direction is bilateral, they split the total tolerance shooting for midpoint, but still have that wiggle room.
On Pin gages Plus is normally your low limit and called the GO, Minus High Limit and No Go.
Rings are reverse that.

Actually the main reason you can't but a gage block or pin "EXACT" size is that it is actually impossible for man to make "Perfect", there is a tolerance to everything. How close to EXACT you get depends on what you want to pay for it. Two people with the same mics taking turns measuring something will get different readings.

Kevin

[smokeywolf]

I have gage pins from I think .013 up to .625. One of my sets is a + set, rest are -. As Doug says, they probably do make on size pins, but in 30+ years as a machinist, I've never run across a need for one. As far as checking your mike, I'd just clean both anvil and spindle surfaces and check .0000, then use a mike standard, gage pin, Johansson block, drill or reamer blank or anything else of known dia. that falls within the upper half of your mike's range.

[smokeywolf]

On Pin gages Plus is normally your low limit and called the GO, Minus High Limit and No Go.
Rings are reverse that.

Kevin

Kevin, are you sure you don't have this reversed. I think its 'minus' on pins that are GO and 'plus' on rings that is GO.

[DougGuy]

Doug, don't want to offend anyone but
Better check your Tolerance Class Chart and math.
ZZ is +/- .0002 nominal
Z is +/- .0001 nominal
Y, X, XX get into "millionths"
"Master" tolerance direction is bilateral, they split the total tolerance shooting for midpoint, but still have that wiggle room.
On Pin gages Plus is normally your low limit and called the GO, Minus High Limit and No Go.
Rings are reverse that.

Actually the main reason you can't but a gage block or pin "EXACT" size is that it is actually impossible for man to make "Perfect", there is a tolerance to everything. How close to EXACT you get depends on what you want to pay for it. Two people with the same mics taking turns measuring something will get different readings.

Kevin

Heh looks like I had it wrong the whole time. I order all my gage pins from Meyer Gage, and I get Z minus pins. I always thought they were -.0002" but they are in reality -,0001" thanks for the clarification.

The ring gages I use to set dial bore gauge I get from fleabay and I get as close as I can to typical boolit diameters. I don't go in fractional or decimal increments on those. I have one that is metric 9 point something mm, but in decimal it is a dead nut .3575" so it's perfect for use with 357/38 caliber cylinders and 9mm barrels. Other sizes are .452" .400" .410" .4326" .477" .500" etc all the way down to .225" for rimfire cylinders.

I think you are reversed on your go/no-go definition though.

From Meyer Gage:


GO/NOGO Measurement – A GO gage is used to check the lower limit of a hole. A NOGO gage is used to check the upper limit of a hole. If the GO gage enters the hole and the NOGO gage is unable to enter, the design specifications of the hole have been met.

For that to work, the NOGO gage has to be bigger than the hole so it would be the plus gage. the GO gage has to be smaller than the hole or it will not enter the hole, so it has to be the minus gage.

[bob208]

i have a set of jo-blocks.

[M-Tecs]

https://www.threadcheck.com/how-to-determine-the-proper-gagemaker-tolerance-for-a-go-no-go-cylindrical-gaging-application/technicalinfo/

[smokeywolf]

The way I read that is, the OD of the GO PLUG is specified at the bottom of the hole tolerance (.499 in their example) with a plus tolerance. This does not make it a PLUS gage.

[sutherpride59]

Thanks for all the great answered guys I honestly never would have guess I would get this many replies.

[chuckbuster]

Doug
I am very sure I do not have it reversed. Let's open the "tolerance up just a little and see where we end up.

Lets say the part print calls for a .500" hole with a tolerance of +/- .0050". So a hole that is anywhere between .495 and .505 is in tolerance. For the Low Limit you use a .495 PLUS pin (in ZZ this will be .4950-.4952) so that you know the hole is big enough and it is called the GO gage since you can go up from there in size. If you use a .495 MINUS pin (.4950-.4948) and it fit you would potentially have undersize (.4948) holes.
High Limit is same principle but opposite direction. .505 MINUS (.5050-.5048) for the NoGo so that you are sure you do not go over your max. You don't want it to fit the hole as it indicates the hole is too big. Using a Plus Pin for high limit (.5050-.5052) makes it even worse.
Used ZZ class Tolerance in this of course as that is the most common in industry for "Work Plugs". Higher Tolerance Classes are used when the +/- range is tighter. Some stuff today there is .0005" or less variance allowed.

Apologies to the OP for getting off on a tangent from the original question. Go/No Go gaging has little if anything to do with calibrating a MIC or other instrument.
Kevin

[DougGuy]

Doug
I am very sure I do not have it reversed. Let's open the "tolerance up just a little and see where we end up.

Let's not open the tolerance and look at what fits and what doesn't.

Say the hole is dead nut .500" and you want to measure and see exactly what it is. You use a minus pin so it will go IN the hole. You do not use a plus pin because it doesn't go in the hole. That's a no brainer.


The simple truth is this. Without clearance, you cannot physically push the pin into the hole. You CANNOT use the same diameter pin as the hole because you would then have to hammer or press it in or freeze the pin (which would make it a minus pin! ). You don't understand the concept of engineered clearance. It is sufficient to say that if a -.0001" pin fits very snugly in the hole, then the hole is "as advertised." This is WHY you gage the lower limit with a minus pin. You want the LARGEST minus pin that will go through the hole. You CANNOT do this with a plus pin.

Let me make it a little clearer. The exact text from Meyer Gage, if the GO gage goes in the hole and the NOGO gage does not go in the hole, the tolerances have been met. Think about that for a second. What they are saying is if the MINUS pin goes in the hole and the PLUS pin does not, the hole diameter is between the diameters of the two pins.

So you use the MINUS pin on the low side, and the PLUS pin on the high side. It can't work the way you state it. The way you explain it, the hole is a non-specified diameter. This cannot exist. The hole is a SPECIFIC diameter, and you measure it with the largest pin that will go through the hole and you proof that measurement by the next size larger pin NOT going through the hole.


Lets say the part print calls for a .500" hole with a tolerance of +/- .0050". So a hole that is anywhere between .495 and .505 is in tolerance. For the Low Limit you use a .495 PLUS pin (in ZZ this will be .4950-.4952) so that you know the hole is big enough and it is called the GO gage since you can go up from there in size. If you use a .495 MINUS pin (.4950-.4948) and it fit you would potentially have undersize (.4948) holes.
High Limit is same principle but opposite direction. .505 MINUS (.5050-.5048) for the NoGo so that you are sure you do not go over your max. You don't want it to fit the hole as it indicates the hole is too big. Using a Plus Pin for high limit (.5050-.5052) makes it even worse.
Used ZZ class Tolerance in this of course as that is the most common in industry for "Work Plugs". Higher Tolerance Classes are used when the +/- range is tighter. Some stuff today there is .0005" or less variance allowed.

Apologies to the OP for getting off on a tangent from the original question. Go/No Go gaging has little if anything to do with calibrating a MIC or other instrument.
Kevin

[ChuckO]

DougGuy and chuckbuster are arguing two sides of the same coin. DougGuy is correct that in finding the size of the hole, the diameter is between the largest MINUS pin that fits in and the smallest PLUS pin that does not fit in. chuckbuster is also correct in stating that a GO-NOGO gage is made from the smallest PLUS pin (to hole nominal - tolerance) and the largest MINUS pin (to hole nominal + tolerance).

Neither statement conflicts with the other, they are measuring two different things, one looking for hole size and the other looking to see if a hole is within tolerance without trying to determine the exact diameter.

[chuckbuster]

I absolutely do understand the principle of "engineered Clearance" I work with it every day. And there is no such thing as an "exact" hole diameter, everything has a tolerance.
Straight from the Meyer Gage Website, Doug needs to read the second paragraph, not just the part that appears to validate his opinion...

"GO/NOGO Measurement – A GO gage is used to check the lower limit of a hole. A NOGO gage is used to check the upper limit of a hole. If the GO gage enters the hole and the NOGO gage is unable to enter, the design specifications of the hole have been met.

Uses – for precision GO/NOGO measuring of hole sizes and depths, checking hole location and distance, and setting micrometers. All gages are uniformly 2″ long with ground ends, allowing you to use both ends for increased gage life. Gages are Carbon Chrome Alloy Steel (grade 52100 bearing quality steel) and heat treated to a 60-62 Rockwell C hardness. All of our products come with a Certificate of Class Conformance, traceable to NIST (National Institute for Standards Technology). The size and “+” (GO) or “-” (NOGO) are laser etched with a Meyer Exclusive Serial Number feature to ensure traceability on your shop floor on all gages that are .061″ and larger."

Kevin

[M-Tecs]

I appears some miss-terminology is being used. Appling the term plus or minus to the function of a GO/NO GO gage is not correct. GO gages go and NO GO gages don't go. Simple as that.

The gage tolerance does come into play for selecting the proper gage for both + and - and %. The industrial standard is the gage tolerance is to be 10% or less than the total part tolerance.

https://www.threadcheck.com/technical-documents/fixed-limit-gage-fact-sheet-pg28.pdf
"HOW TO DETERMINE AND SELECT THE PROPER TOLERANCE FOR YOUR GAGING APPLICATION The normal rule of practice requires 10% of product tolerance to be divided between the “ GO “and“ NOGO “ gages. For plug gages, a plus tolerance is applied to the GO member and a minus tolerance to the NOGO member. Ring gages receive reverse tolerance direction so that the “ GO “ member is minus and the “ NOGO “ is plus tolerance. Applying this practice results in gage tolerance always being included in the part tolerance by up to 10%. This results in the possibility that 10% of good product could fail inspection but that no bad product "


Example would using pin gages to check a 1.000" +.001" hole.

The go gage pin would be 1.000" with a plus tolerance of whatever class is required. The gage tolerance is this case would 50 millions or better for a total of .0001" for both gages. The gage tolerance provides the required fit. The plus tolerance of the gage pin insures that the hole is 1.000" plus something.

The no go gage pin would be 1.001" with a minus tolerance of whatever class is required. The gage tolerance is this case would 50 millions or better for a total of .0001" for both gages. The gage tolerance provides the required fit. The minus tolerance of the gage pin insures the hole is 1.001" minus something.

If using a ring gage the tolerance would be reversed.

When using gage pins to check hole sizes you can use either + or - pins. You just can not determine size closer than the tolerance of your gages or the step sizes you have available. I used to work for a company that had pin gages in both + and - in .0001" increments from very small to 2" plus metric and special sizes. Total was about 23,000 + gages