Micrometer "feel" - Page 7
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  1. #121
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    If it reads off-zero, that probably means somebody used it for a C-clamp.

    If the error is more than one or two tenths the frame is likely bent, so I'd trash it and use another one.

    - Leigh

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    It sounds like everyone is answering the afterposts not the original question. Where did standards come from? Anyways. I have the same set of mics. Try using spring calipers for a moment. See how the metal to metal contact feels. It will give u a good idea what mics are suppose to feel like. Position the mic close to the apex of the radius. Start moving horizontally with slight movements turning anvil down. The moment it starts to get stuck, decrease horizontal and radial movements to slight twitches gradually turning thimble. Once you feel consistency in the rubbing gently pull the mic off the material while watching the dial.. Straight on straight off because there is no lock. Your mics are fine just have them calibrated regularly and keep them clean and oiled.

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    get someone to show you.

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    Quote Originally Posted by QC Dude View Post
    Also, especially if I'm using someone elses instrument, the first thing I do is acquaint myself with it's zero and try to replicate the same pressure when measuring.
    Your never going to get your hands on my Micrometer period. You are Q.C. Dude and you don't have your own?

    Robert

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    Quote Originally Posted by litlerob View Post
    Your never going to get your hands on my Micrometer period. You are Q.C. Dude and you don't have your own?

    Robert
    Haha! I do! Sometimes I make spot checks at the machines and use the operators.

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    Quote Originally Posted by Gordon B. Clarke View Post
    If you really work with QC are you verifying that the guy that owns the micrometer makes parts to "his" spec or that the parts are in fact to spec?

    Alarm bells should be going off in your head if what is or has been used to measure seems incorrect.

    Do you in fact work within QC?

    Gordon
    Always to spec and all the instruments on the floor are calibrated by us (our QC guys).

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    How about larger/heavier micrometers like 2 feet / 600mm.

    I can’t trust to myself so much that I could measure with feel, I use ratchet always. Also I bring the micrometer few hours or day before measuring to lathe with standards which came with micrometers. Before measuring, I always check the micrometer to standard, micrometer usually laying on table. If I’m measuring some more critical like tens of thousands dollars/euros worth of workpiece and gonna measure it with arc to top, I also calibrate the micrometer with arc on top, because it gives different results depenging on the measuring position. Today it showed 0,005mm difference on 600mm micrometer.
    I check the calibration once in a while, because micrometer can get warmed up or when doors are open it can get colder.

    How other machinists measure with these larger micrometers, with feel or ratchet etc?

    On page 9, pdf page 11 is about how support position effects to results.

    https://www.mitutoyo.com/wp-content/...QuickGuide.pdf

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    Quote Originally Posted by Jani73 View Post
    How about larger/heavier micrometers like 2 feet / 600mm.

    I can’t trust to myself so much that I could measure with feel, I use ratchet always. Also I bring the micrometer few hours or day before measuring to lathe with standards which came with micrometers. Before measuring, I always check the micrometer to standard, micrometer usually laying on table. If I’m measuring some more critical like tens of thousands dollars/euros worth of workpiece and gonna measure it with arc to top, I also calibrate the micrometer with arc on top, because it gives different results depenging on the measuring position. Today it showed 0,005mm difference on 600mm micrometer.
    I check the calibration once in a while, because micrometer can get warmed up or when doors are open it can get colder.

    How other machinists measure with these larger micrometers, with feel or ratchet etc?

    On page 9, pdf page 11 is about how support position effects to results.

    https://www.mitutoyo.com/wp-content/...QuickGuide.pdf
    Good luck with trying to get anyone to change their opinion or mind re "How they've always done it".

    Personally, if a micrometer has a ratchet I use the ratchet. That's how it was tested where it was made.

    din863.jpg

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    Quote Originally Posted by Jani73 View Post
    How about larger/heavier micrometers like 2 feet / 600mm.

    How other machinists measure with these larger micrometers, with feel or ratchet etc?

    On page 9, pdf page 11 is about how support position effects to results.

    https://www.mitutoyo.com/wp-content/...QuickGuide.pdf
    The friction or ratchet is the preferred method. Whatever you do you should use the mic like it was set (or checked & mentally adjust if you prefer it that way).

    Your linked pages show what happens when you support the bottom, mid-frame etc. for setting & then measure holding/turning another way, the larger the mic the worse it gets.

    From 1”-6” I generally support the bottom, then from 6 -12” I hold the mic mid-frame, I prefer to set all those horizontally on a mic tree. Larger than that you should properly support the rod standards for the way you use the mic, then check & use the mic with the same support & orientation as you checked them with.

    Good luck,
    Matt

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    At least he's using the ratchet.

    YouTube

    With the next one I don't even know where to begin

    YouTube

    The items in this aren't something anyone can measure.

    YouTube

    Depending on the accuracy required of course measuring the circumference of something round is one way to go.

    Circometer: IPT Institut fur Pruftechnik Geratebau GmbH & Co. KG

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    We have also circometers. Used those, when I turned some large rubber drums.

    We have Mitutoyos micrometers up to 2000mm, those are pretty straightforward to use on horizontal lathe, because those have adjustable support, so you can measure with it without help from another person.

    On our Tos vertical lathe, there is probe, which can be used to measure workpieces instead of micrometers.

    On our new mill, the Y axis is 6000mm/19 feet 8 inch.
    Attached Thumbnails Attached Thumbnails 51da957a-2770-4b21-992e-7808af84a4de.jpg  

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    I use a come here motion with a single finger as my friction clutch with the pinky or ring finger through the frame. It seems to agree with the clutches and ratchets on my Mitutoyos so I've stuck with it.

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    never oil the threads!!!

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    Quote Originally Posted by cmailco View Post
    Good advice thus far.

    Only thing I'd add is that developing a method of consistent measurement is key, regardless the type of measuring tool.

    I don't particularly like 'ratcheting' types, but that's more a personal preference than anything. However, if you calibrate them to some standard method... say, light approach, then 3-clicks... then as long as you use the same methodology when measuring, you should achieve accurate results.


    GL
    I agree. Consistency is critical.
    If your set didn't already come with the length standards, get a set - 1 for the "0" of each micrometer. (If your measurements require reading to .0001", you probably need a 91 piece Gage Block set to allow for checking different points throughout the range of each mic...)
    Next, as previously stated by others-set your micrometers to those standard. Then USE THE SAME AMOUNT OF TORQUE WHEN MEASURING. The fact is, although it is ill-advised: I can make a micrometer accurate using 15 lbs of torque if I set it with the same torque as I measure with.
    As for an exact #, the ratchets and friction thimbles are engineered so that 1 lb of force can make them stop - which is the counterweight used on a MicTrac for most instruments.
    BOTTOM LINE: Make sure to set your 0 with a good standard. Once you have the 0 set, use the same torque to measure with. The best way to learn is just getting in there and measuring

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    Quote Originally Posted by Jtommr View Post
    I have a set of Mitutoyo micrometers with .0001" resolution. They are the most basic model, no lock or ratchet. In order to get accurate, repeatable results at the finest resolution, I'm trying to develop a sense of feel for their use.

    What is the correct amount of pressure to apply to the part being measured? How much is too much?
    Feel the micrometer to a jo-block with your eyes closed until you get the correct feel to correct number. likely to develop a feel good for +- .0002

    Most/many old timers think .00025 is likely with a good quality .001 resolution micrometer.
    Half way between the numbers is .0005
    Some think the hand feel to the thimble is the key and others think the feel of sliding anvils on the part is king.
    A go / no gauge is the feel of the gauge to the part and good for +- .0002 and better..

    friction or ratchet micrometers should also be tested on a jo-block to be sure they are still in tune for correct measure.

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    Quote Originally Posted by Luke.kerbey View Post
    never oil the threads!!!
    Given how many micrometers I've seen rusted from coolant or abuse, dry, with threads packed with carbon, cast iron grit etc., I'd guess there's a reason for Starrett Tool and Instrument Oil?

    Typical mic service is to clean it, lightly lube it with instrument oil, adjust and calibrate as required. If in calibration, it goes back into the shop. If out, it gets pitched or (if employees own their own tools) back to the owner without a calibration sticker. In the old days, mics were even sent out to have the anvils lapped. These days, and with better carbide anvils, a worn mic is more likely replaced. And there really isn't a simple cure for spindle thread wear (which can be very uneven if, say, the same dimension is miked over and over again). Best you can do is keep that thread clean and lubed.

    Mics come from the factory -- and are calibrated -- with a very light coat of oil. They ought to have that same very light coat of oil replaced as needed in the years ahead.

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    Quote Originally Posted by michiganbuck View Post
    friction or ratchet micrometers should also be tested on a jo-block to be sure they are still in tune for correct measure.
    No point in me replying to the rest of your post as we obviously live in very different worlds.

    As to "a jo-block" singular then that isn't calibration. I'm sure somebody like MattiJ can tell you/us how to do a correct calibration.

    There is a standard that as good as all follow (DIN 863) and that includes Mitutoyo. I have it but in German.

    DIN 863-1 - 2017-02 - Beuth.de

    http://www.hartig-germany.com/tutori...icrometers.pdf

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    Gordon perhaps your answer to the OP is send the manual micrometer to a calibration shop and get it rebuilt and reset.
    and still you have not answered the op's question.

    QT: [As to "a jo-block" singular then that isn't calibration.] Agree but at a years, weeks or day's use, perhaps dropped a few times by the apprentice how do you know the micrometer is still correct...We/I would check it with a calibrated Jo block on the shop flood. We/I also would check a part to a Jo block stack for a plate check when needing such.

    I still compare to a Jo block stack with setting zero, using my dial micrometers...

    I made gauges that way and they were final inspected by the inspector with a cmm, some down to 6 to 12 millionths spec and I would try to beat the spec..Yes retired from close work in 2004.

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    Quote Originally Posted by michiganbuck View Post
    Gordon perhaps your answer to the OP is send the manual micrometer to a calibration shop and get it rebuilt and reset.
    and still you have not answered the op's question.

    QT: [As to "a jo-block" singular then that isn't calibration.] Agree but at a years, weeks or day's use, perhaps dropped a few times by the apprentice how do you know the micrometer is still correct...We/I would check it with a calibrated Jo block on the shop flood. We/I also would check a part to a Jo block stack for a plate check when needing such.

    I still compare to a Jo block stack with setting zero, using my dial micrometers...

    I made gauges that way and they were final inspected by the inspector with a cmm, some down to 6 to 12 millionths spec and I would try to beat the spec..Yes retired from close work in 2004.
    The OP's post is from 2012 and I was responding to your post, not his


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