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Thread: What gauge for micrometer

  1. #21
    Boolit Master bosterr's Avatar
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    Quote Originally Posted by DougGuy View Post
    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?

  2. #22
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    Quote Originally Posted by bosterr View Post
    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.
    Got a .22 .30 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throats honed? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? 480 Ruger or 475 Linebaugh cylinder that needs the "step" reamed to 6° 30min chamfer? Click here to send me a PM You can also find me on Facebook Click Here.

  3. #23
    Boolit Master bosterr's Avatar
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    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.

  4. #24
    Boolit Master chuckbuster's Avatar
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    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
    Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change? (Sgt. Oddball, KELLY'S HEROES)
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  5. #25
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    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.
    A well regulated militia, being necessary to the security of a free State, the right of the People to keep and bear arms *shall not be infringed*.

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  6. #26
    Boolit Master
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    Quote Originally Posted by chuckbuster View Post
    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.
    A well regulated militia, being necessary to the security of a free State, the right of the People to keep and bear arms *shall not be infringed*.

    "The greatest danger to American freedom is a government that ignores the Constitution."
    - Thomas Jefferson

    "While the people have property, arms in their hands, and only a spark of noble spirit, the most corrupt Congress must be mad to form any project of tyranny."
    - Rev. Nicholas Collin, Fayetteville Gazette (N.C.), October 12, 1789

  7. #27
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    Quote Originally Posted by chuckbuster View Post
    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:

    Quote Originally Posted by 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.
    Last edited by DougGuy; 10-13-2017 at 11:32 PM.
    Got a .22 .30 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throats honed? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? 480 Ruger or 475 Linebaugh cylinder that needs the "step" reamed to 6° 30min chamfer? Click here to send me a PM You can also find me on Facebook Click Here.

  8. #28
    Boolit Master
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    i have a set of jo-blocks.

  9. #29
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  10. #30
    Boolit Master
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    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.
    A well regulated militia, being necessary to the security of a free State, the right of the People to keep and bear arms *shall not be infringed*.

    "The greatest danger to American freedom is a government that ignores the Constitution."
    - Thomas Jefferson

    "While the people have property, arms in their hands, and only a spark of noble spirit, the most corrupt Congress must be mad to form any project of tyranny."
    - Rev. Nicholas Collin, Fayetteville Gazette (N.C.), October 12, 1789

  11. #31
    Boolit Master

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

  12. #32
    Boolit Master chuckbuster's Avatar
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    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
    Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change? (Sgt. Oddball, KELLY'S HEROES)
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  13. #33
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    Quote Originally Posted by chuckbuster View Post
    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.

    Quote Originally Posted by chuckbuster View Post
    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
    Last edited by DougGuy; 10-15-2017 at 04:36 PM.
    Got a .22 .30 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throats honed? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? 480 Ruger or 475 Linebaugh cylinder that needs the "step" reamed to 6° 30min chamfer? Click here to send me a PM You can also find me on Facebook Click Here.

  14. #34
    Boolit Bub
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    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.

  15. #35
    Boolit Master chuckbuster's Avatar
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    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
    Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change? (Sgt. Oddball, KELLY'S HEROES)
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  16. #36
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    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/technica...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
    Last edited by M-Tecs; 10-20-2017 at 04:39 AM.

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