First Time Gage Block Calibration
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    Default First Time Gage Block Calibration

    Hey all,

    We recently got a Keyence IM7030 measuring machine. I'm told by Keyence that it's suitable for re-certifying Pin Sets of class ZZ, and Gage Blocks of Grade 3 (or AS1). I'm currently trying to certify an old set of Mitutoyo Blocks Model 516-935.

    Most of my blocks are reading over tolerance. Wouldn't old blocks be under tolerance from wear over time rather than over? Any suggestions on cleaning the blocks? (maybe they just need a good cleaning to remove excess material?)

    I'm trying to determine if I'm doing it wrong, my machine is wrong, or my blocks are just out of calibration. Any tips would be appreciated.

    Thanks.

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    Might try reading a known calibrated block first as a check that it's you or the machine, rather than the blocks.

    Most block sets have a mix of over and undersize. As you say, if the blocks are uniformly worn they might read under. However, if the blocks have been nicked or scratched, they might read over. If you're not wringing them to a reference surface that could be another issue.

    Do you have a calibration standard for your measuring machine?

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    Well I appreciate the response, but I just got off the phone with Keyence Corp, and the machine is not accurate out to ±8 microinches. It's suitable for the gage pins we do, but not to blocks of AS1 or better.

    Thanks anyway!

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    if I understand this correctly, you're optically measuring from one face to the other face. If your reference surface, ie the side of the gage block isn't perfectly square to the faces, it's going to measure oversize. Unfortunately, the sides of a gage block are nowhere near square enough to do what you are trying to do.

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    Quote Originally Posted by J Skeleman View Post
    Hey all,

    We recently got a Keyence IM7030 measuring machine. I'm told by Keyence that it's suitable for re-certifying Pin Sets of class ZZ, and Gage Blocks of Grade 3 (or AS1). I'm currently trying to certify an old set of Mitutoyo Blocks Model 516-935.

    Most of my blocks are reading over tolerance. Wouldn't old blocks be under tolerance from wear over time rather than over? Any suggestions on cleaning the blocks? (maybe they just need a good cleaning to remove excess material?)

    I'm trying to determine if I'm doing it wrong, my machine is wrong, or my blocks are just out of calibration. Any tips would be appreciated.

    Thanks.
    Keep in mind when working with tight tolerances especially on gage blocks and pins, temperature is a big factor. Good choice to call in and ask.

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    I would start with measuring a recently certified block, and see how close your results match with a 3rd party calibration lab, and if the difference is less than uncertainty of measurement.
    As jz814 mentioned, environmental conditions do make huge difference. Temperature does not only affect the block, but also every part of your Keyence machine. Most metrology labs maintain temperature at 20 +/-0.1 degree C. Other factors such as humidity and amount of airborne particles are also tightly controlled.
    Your Keyence probably came with a calibration certificate, it should specify environmental conditions used during calibration. Expect to maintain similar conditions in order to achieve stated accuracy and uncertainty.
    Last edited by zsinstruments; 09-24-2019 at 07:32 PM.

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    Quote Originally Posted by Larry Dickman View Post
    if I understand this correctly, you're optically measuring from one face to the other face. If your reference surface, ie the side of the gage block isn't perfectly square to the faces, it's going to measure oversize. Unfortunately, the sides of a gage block are nowhere near square enough to do what you are trying to do.
    Isn't this strange when you first encounter it.
    I used to think of gage blocks as mini 1-2-3s and that the sides would be square so I would trust this in fixturing at 90.
    Turns out I was wrong and messed up a lot of parts. Assume only the gage faces true to each other. All other surfaces to be suspect.
    Bob

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    I seem to recall gage blocks were deliberately made towards the top of their tolerance to prolong their useful life perhaps even with a touch-up lap to dress a surface that will no longer wring.

    Regardless, anyone assembling a gage block stack would be wise to consult the calibration sheet so that in-tol size variations can be summed. A stack of 8 blocks will have 8 calibrated errors. If your shop grade blocks are new and average 4 millionths (1 micron) over nominal size that's 32 millionths error in the plus direction. That's significant when working to small tenths.

    Someone mentioned temperature. Most gage block sets are steel. If the block stack and the part under inspection are both steel and at the same temperature no compensation is necessary. If the work is bronze, aluminum, etc, and above or below the international standard gaging temperature of 68 degrees F (20 degrees C) you have to work the math cranking in work temperature, gage temperature, coefficients of linear expansion, etc to determine the final compensated size. If you work to sub-thousandths (sub 0.04 mm) on larger work in an open shop, your best friend is a pocket thermometer and, if possible, time for thermal equilibrium to work its magic. Your worst enemies are sunlight, drafts, and radiant heat.

    Story: I recall working on a rudder stock for an aircraft carrier. This was a huge part 42" on the largest diameter and 12ft+ long. It was made for humongous roll neck bearings the largest I've ever seen. The seal had failed admitting salt water into roller bearing country with expected results: the bearing seats had to be machined to sound metal, built up with weld, and remachined. Except for the magnitude, not that much of a job; routine.

    But the plan tolerance for the bearing fits were +0.001"/-0.000", roughly 1 part in 40,000. Proportioned to 4" dia the tolerance would be +0001"/0.0000". The plan had "Non Deviation" stamped on it so we were locked in. We had a big mike (we had them up to 60") specially calibrated to the diameter to be measured and three graveyard guys took the final readings when the shop was quiet and the temperature was at equilibrium. PITA. The bearing bore tolerance was +/- 0.0030" and the interference was 0.020" or so. That extra close tolerance probably cost the taxpayer $1500 over and above to validate.

    The moral is: never allow a young enthusiastic parts detailer to set close tolerances. Put him under a hard core lead engineer.

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    Wow, Forrest Addy is back after over one year break!
    I was already afraid of the worst, nice to see You back here.

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    Quote Originally Posted by Forrest Addy View Post
    I seem to recall gage blocks were deliberately made towards the top of their tolerance to prolong their useful life perhaps even with a touch-up lap to dress a surface that will no longer wring.
    Not to argue with the statement, just adding a reference point, but I have a new Mitutoyo 9pc grade 0 fresh from the cal lab says 4 of them are under, 2 are spot on, and 3 are above. Most any are out is 2 millionths. Don't use many gage blocks here so those are all I've got to reference calibrated numbers from.

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    Why not send the blocks out to a specialist for calibration? Up here we use Productivity Quality Inc.

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    With the upgrades to our measurement technology here we thought we might be able to do it in-house. If we could save some money doing that and still have the same fidelity of testing as an outside source, why not?

    The thought was that down the road, if we can produce calibration results in parity with an accredited metrology house, maybe we would seek our own accreditation.

    For the moment anyway, we've sent them out. Maybe we'll have something worked out for next time.

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    Quote Originally Posted by mhajicek View Post
    Why not send the blocks out to a specialist for calibration? Up here we use Productivity Quality Inc.
    With the upgrades to our measurement technology here we thought we might be able to do it in-house. If we could save some money doing that and still have the same fidelity of testing as an outside source, why not?

    The thought was that down the road, if we can produce calibration results in parity with an accredited metrology house, maybe we would seek our own accreditation.

    For the moment anyway, we've sent them out. Maybe we'll have something worked out for next time.

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    Quote Originally Posted by J Skeleman View Post
    The thought was that down the road, if we can produce calibration results in parity with an accredited metrology house, maybe we would seek our own accreditation.
    We're currently working on ISO 17025 here, if you don't need it I sure wouldn't do it for the fun.

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    Quote Originally Posted by Forrest Addy View Post
    rudder stock for an aircraft carrier. This was a huge part 42" on the largest diameter and 12ft+ long. It was made for humongous roll neck bearings the largest I've ever seen. The seal had failed admitting salt water into roller bearing country with expected results: the bearing seats had to be machined to sound metal, built up with weld, and remachined. Except for the magnitude, not that much of a job; routine.

    But the plan tolerance for the bearing fits were +0.001"/-0.000", roughly 1 part in 40,000. Proportioned to 4" dia the tolerance would be +0001"/0.0000". The plan had "Non Deviation" stamped on it so we were locked in. We had a big mike (we had them up to 60") specially calibrated to the diameter to be measured and three graveyard guys took the final readings when the shop was quiet and the temperature was at equilibrium. PITA. The bearing bore tolerance was +/- 0.0030" and the interference was 0.020" or so. That extra close tolerance probably cost the taxpayer $1500 over and above to validate.

    The moral is: never allow a young enthusiastic parts detailer to set close tolerances. Put him under a hard core lead engineer.
    LOL! Any "old salt" who's ever served on a warship as survived severe storm if not also battle damage and had to work hard to stay afloat and keep punching back wouldn't hurt, either!

    One does wonder just how much the structure those uber-precise bearings were hung to moved at least a tad at sea, not just off the back of temperature swings? And if self-aligning critters in adjustable housings might not have made better sense?

    There's precedent. Bismark's rudder jammed hard-over shortened her "service life". An IJN warship as had to blow a battle-damaged rudder unrepairable at sea clear OFF with explosives so she could die another day.

    How soon we forget these hulls are MEANT to "go in harm's way" and JF deal with the consequences.

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    Forest, good to see you back...been worried about you, where have you been?

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    Default Somewhat OT

    Quote Originally Posted by thermite View Post
    There's precedent. Bismark's rudder jammed hard-over shortened her "service life". An IJN warship as had to blow a battle-damaged rudder unrepairable at sea clear OFF with explosives so she could die another day.
    In odd encounters, I met a woman not long back whose father was a diesel mechanic on the Bismark. An interesting story. Crew were stranded in Argentina after the scuttling. Not POW's exactly but sort of house arrest. While there, a Mennonite woman undertook to teach Spanish to those interested and this guy joined. End of war and he's still there earning a living, and while on a bus sees the Mennonite from the bus window and jumps off to talk and thank her. One thing led to another, the couple moved to the US where he was recruited later to maintain diesel generators for VOA transmitters around the world. I met the daughter in Austin and would never have known if someone hadn't prompted me to talk to her as we both have an Africa connection. A very interesting world.

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    Quote Originally Posted by TGTool View Post
    In odd encounters, I met a woman not long back whose father was a diesel mechanic on the Bismark. An interesting story. Crew were stranded in Argentina after the scuttling. Not POW's exactly but sort of house arrest. While there, a Mennonite woman undertook to teach Spanish to those interested and this guy joined. End of war and he's still there earning a living, and while on a bus sees the Mennonite from the bus window and jumps off to talk and thank her. One thing led to another, the couple moved to the US where he was recruited later to maintain diesel generators for VOA transmitters around the world. I met the daughter in Austin and would never have known if someone hadn't prompted me to talk to her as we both have an Africa connection. A very interesting world.
    That wudda been "Admiral Graf Spee". One if not two classes smaller, as Kriegsmarine warships were in the day. Done to her demise by smaller Royal Navy ships with far smaller guns and nought but the balls to just get in CLOSER to make 'em count before they went dark.

    Bismark took most of her crew down with her. "net sez:

    Out of her crew of 2,200, there were only 115 survivors. Only 2 officers out of 100 survived.
    Wanna know a coupla things even DUMBER than a BMW about "Superior German Engineering"?

    1) Graf Spee was too crippled to risk a fight due to shell and shrapnel holes. But not in her armoured hull. In her crucially important Diesel recip's supercharger rig!

    2) Bismark & Tirpitz had hydraulically traversed main-battery turrets.

    To avoid risk of damaged high pressure lines and fluid leaks incapacitating the gun crews or fueling a fire?

    The clever buggers simply ran the hydraulic lines OUTSIDE the turret armour!

    No problem!

    Anything 20 mil autocannon on up - .50 cal "only maybe", could shred the lines.

    And did. Shrapnel and secondary-battery fire, mostly. Not that a seriously browned-off Royal Navy was all that stingy with shellfire, what with around 400 hits registered out of 2,800 fired...

    Bismark's lethal 15" turrets went useless at shooting back in any "selectable" direction as actually had a TARGET in it rather than hundreds of square miles of empty ignorant seawater!

    I did say dumber than a BMW?


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    Yup, my mistake.

    According to my informant, the Graf Spee was damaged enough she couldn't go out and face battle so put into port. Argentina, as a third party would allow repairs only to non-weapons systems. Judging they had no better choices, the officers evacuated the crew and scuttled her in the harbor.

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    Quote Originally Posted by TGTool View Post
    Yup, my mistake.

    According to my informant, the Graf Spee was damaged enough she couldn't go out and face battle so put into port. Argentina, as a third party would allow repairs only to non-weapons systems. Judging they had no better choices, the officers evacuated the crew and scuttled her in the harbor.
    Argentina would almost certainly have allowed her to stay as long as required for full repairs had she still had the speed to reach Buenos Aires from Montevideo, Uruguay. It isn't that far.

    Graf Spee likely had "enough" pre-cleaned fuel for the run. Diesels already overdue for overhaul, could have risked running them to death at emergency flank the whole way, perhaps 30 kts -plus a bit?.

    Fastest ferry on the present-day run - Tasmanian design, Argie built, similar catamaran hull to those on the Hong Kong <-> Macau run - has a max of just short of double that, so...

    However ...with one or more of her diesels unable to develop full normal power, she no longer had the speed, was prepared for, and professionally scuttled instead to keep her secrets.

    Scuttled "too soon" as happened. To add insult to injury , the water was shallow enough the Brits got salvage rights and figured out she had radar fire-direction - the first-ever for Germany - anyway!

    Some days you eat the lion. Other days the lion eats your remains.


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