Micrometer standards are not very accurate? - Page 4
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  1. #61
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    In case it matters, when we bought our micrometer master, we got inspection certs with it. They were closer than +-.0001. It was more like +-.00005

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    Quote Originally Posted by cgrim3 View Post
    In case it matters, when we bought our micrometer master, we got inspection certs with it. They were closer than +-.0001. It was more like +-.00005
    Good on yah!

    Been discussed, other threads as well over the years, that the best of goods, those figures can be trusted, and the WORST of goods the incoming certs are basically just faked!

    Accordingly, as I don't NEED traceability - (stuff I do just has to fit OTHER stuff that is also under my own roof anyway), I'm happier with top-name goods and certs many years out of date than with brand-new Chicoms and phoney certs.

    Well even so, I have a 0-6" set of rather NICE B&S-pattern "tenths" mics that check out spot-on even against US-made standards, so it isn't that bad. Just unpredictable.

    Yazz, gage block and mic standards do drift a tad over time. But still..

    Most any "smallholder" would need regular demanding-contract work, a seriously touchy product, or an aerospace revenue shop's BUDGET to do much better.

    Damned few have that.

    Sure enough. Those folk who haveth not will be the most opinionated ABOUT it, too!

    Go figure it's human nature that our most cherished and loudest claims to expertise are ever the ones with the least foundation under 'em?

    Well.. anything else costs more actual MONEY than an unfounded opinion, so mayhap it's just a sign of righteous frugality?

    I did say "human nature"?


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    Quote Originally Posted by EmanuelGoldstein View Post
    You are such an idiot .... ask Mert who designed and built the clutches he sold. And made the cast mag camcases. Or ask Peter Zylstra who did the original ver 2 XR clutches. Go ahead, get on the phone, big shot.

    Attachment 318647

    Attachment 318648



    I didn't do these, mine are nicer, these are the followup after I left the US. Made hundreds, if not thousands. Surprised there's that many old trumpets out there.



    I modeled our wheels, friend did the FEA cuz I ain't that smart :



    There's plenty more where those came from, all I have to do is find them ...

    Now will you shut up ? Go bother termite.
    LOL! Never thought I'd see the day, but when you ain't flogging bad politics?

    "Good ON YAH!"



    No foul sending the idjut my way. "Bring it!"

    His coprophilia saves me a ton off needing less toilet-paper!


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    RE:[Micrometer standards are not very accurate?]

    But at +- .0001 and better they are plenty close enough for most jobs/work/print needs.

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    Most love and trust "outside calibrated" to all kinds of zeros.
    Anyone every send masters or blocks to a NIST traceable calib house, a week later to a second, and then too a third?
    Now I zero to one of these "trusted" masters but is there any error in doing so? What makes my use perfect in zeroing? If error as I zero how much?
    Oh my, known unknowns.
    A rabbit hole that is hard to come out of sane.

    End deal is functionally and/or customer or receiving inspection satisfaction.
    I do so hate the going cross country to prove my parts in spec while the dock or some engineer has held them as bad due to their not understanding gage errors.
    Everyone loves a CMM, everyone thinks they can do surface Ra by eyeball.

    Accept that your measuring is not perfect and never will be. Stay a lot away from any tolerance or this me vs them will bite you. 25% sort of the min, 50% better.
    I know that chop all my given print tolerances in half when making seems so insane.

    Gauge block or rounded tip master when mic used on a lathe? As said..... rabbit hole.
    Bob

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    Do you have this specific micrometer tree Bob?

    112E Glastonbury Southern Gage Micrometer Master - English

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    I think I've seen way more errors caused by QC mistaken processes than ever caused by errors of measuring instruments themselves. Not that there couldn't be measuring instrument errors, but if you'd run a statistical analysis of where the errors entered .... Just sayin'

    Like the time the QC first piece analysis of a new molded part flagged a mispositioned hole. First eyeball looks at me, the mold designer. So back to the engineering drawing, add shrink allowance to their dimension, look at the mold insert stackup and no sign of the error on the design side. Next it's time for the toolroom to disassemble the mold (outside build) and measure the true size of inserts and hole locations. Still no sign of the cause. Ask QC to check the molded part again and they get nominally the same number. How the fuck do you fix a problem you can't find the source of? As a last resort, go round to QC and ask to see them measure the part again. Light finally dawns. They measure on the CMM they've recently gotten and are quite proud of, and read the hole position by dropping a tapered probe into the hole. QC does not notice that the mold operator nicely enough filed the flash out of the hole on that side so the location of a filed out widely tapered opening as measured by a tapered pin is anybody's guess.

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    Quote Originally Posted by cgrim3 View Post
    Do you have this specific micrometer tree Bob?

    112E Glastonbury Southern Gage Micrometer Master - English

    No.............

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    Quote Originally Posted by TGTool View Post
    I think I've seen way more errors caused by QC mistaken processes than ever caused by errors of measuring instruments themselves. Not that there couldn't be measuring instrument errors, but if you'd run a statistical analysis of where the errors entered .... Just sayin'

    Like the time the QC first piece analysis of a new molded part flagged a mispositioned hole. First eyeball looks at me, the mold designer. So back to the engineering drawing, add shrink allowance to their dimension, look at the mold insert stackup and no sign of the error on the design side. Next it's time for the toolroom to disassemble the mold (outside build) and measure the true size of inserts and hole locations. Still no sign of the cause. Ask QC to check the molded part again and they get nominally the same number. How the fuck do you fix a problem you can't find the source of? As a last resort, go round to QC and ask to see them measure the part again. Light finally dawns. They measure on the CMM they've recently gotten and are quite proud of, and read the hole position by dropping a tapered probe into the hole. QC does not notice that the mold operator nicely enough filed the flash out of the hole on that side so the location of a filed out widely tapered opening as measured by a tapered pin is anybody's guess.
    Jayzuss.

    No need of a new tire.

    Just pull the one you have and turn it over.
    End of problem!

    It's only flat on the BOTTOM, after all!



    cgrim:

    There are several other styles and more than one maker of micrometer set masters.
    Not a lot of "magic" to them.

    Take note as to what the spcs you linked call for. Ground and lapped to a "tenth". No more than that.

    Space and money wasters some might class them.

    "Depends"

    Your shop, your needs, your choice of solution.

    Whatever works for you, works. For you.

    BFD

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    Can we agree that any is better than none once above a zero to one mic?
    One needs something to believe in.
    Bob

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    Big errors are often not in measuring.
    The errors in a 4jaw held part indicated to .0001 .. but having a .0005 wobble in the chuck.
    A shaft to hold a set high precision bearing with .00015 wobble at each bearing fit.
    a .0002 spec in the design of a precision shaft so putting the very best bearings on a wobble shaft.
    Likely the/a best talent for a lathe guy is to know when to go to between solid centers.

    That Glastonbury is a good gauge..it is difficult to set larger micrometers to JoBlock, so +-.0001 is good/close.
    No, I don't have that gauge.
    With my calibrated JoBlocks I could check a 12" mic..but would have to add the calibration errors.

  13. #72
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    Quote Originally Posted by CarbideBob View Post
    Can we agree that any is better than none once above a zero to one mic?
    One needs something to believe in.
    Bob
    I believed in getting PAID.

    "Realists" just go TF back to work so long as they accept they will never be Dead Nuts, but ARE comfortable they are within a "good enough" margin of error to succeed at whatever TF constitutes a "deliverable'.

    Ultimately, only a gage or metrology instrument maker has to hit "what passes for" an absolute.

    Everyone else?

    Thing "a" must fit thing "b".

    Or the functional equivalent thereof as to the incoming QC of (s)he who releases the payment.

    Or will not.

    As "no one ever WON an argument with a customer"... there's ALWAYS a "price"..

    Reality sets in soon enough. One goes and FINDS OUT what is required to "succeed" in that moment... then JFDI.

    ELSE The classical spiderweb forms across the anus, corporate or personal, either one.

    Starvation having cured shitting.



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