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ID micrometer, is it worth buying one?

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  • Mcgyver
    replied
    Originally posted by Gordon DK View Post
    Thanks for the warm welcome.
    hey come on, got a problem with our goodwill ambassador?

    j/j, welcome to the forum

    Leave a comment:


  • JCHannum
    replied
    Apparently the OP was using a vernier caliper for measurement. While I don't feel any slide caliper is the best choice for ID measurement, the vernier caliper is the most accurate of the three types available. This is not my opinion, it is backed up by Starrett.

    ID measurements are problematic at best, and for the best true measurement, standards are required for calibration regardless of the instrument used to ensure the instrument is reading correctly. When making a measurement with one instrument, such as an OD mic and boring to a dimension measured with another instrument, in this case an ID mic, unless both instruments are calibrated to known standards, the outcome is always in question. That is why several responses suggested the use of Jo-blocks.

    For comparative measurement, proper technique with good quality telescoping gages and either of the three slide calipers will be of sufficient accuracy in the case of the OP's application.

    Welcome to the forum.

    Leave a comment:


  • becksmachine
    replied
    Good eyes Gordon.

    Allow me to offer you a more gracious welcome, glad you are here.

    Dave

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  • Gordon DK
    replied
    Originally posted by Jaakko Fagerlund View Post
    Really shows that you didn't read the replies. NOBODY has suggested using (vernier) calipers for measuring the bore.
    I suggest you read post #9 written by the OP. I also suggest you re-read what I did write in post #64.

    Thanks for the warm welcome.

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  • Jaakko Fagerlund
    replied
    Originally posted by Gordon DK View Post
    This is my first post so here goes.

    Measuring bores intended for bearings with a dial or digital caliper is close to suicide and with a vernier caliper should be against the law.

    A 3 point digital bore micrometer is of course best but a two point micrometer such as Mitutoyo # 145-185 (5 - 30mm) is preferable to a caliper.

    I haven't read all the posts but I'm sure some must have written the same.

    Gordon
    Really shows that you didn't read the replies. NOBODY has suggested using (vernier) calipers for measuring the bore.

    Leave a comment:


  • MrSleepy
    replied
    Optical bore guages are nice to use.. I got a set for a reasonable price of ebay

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  • tdmidget
    replied
    Originally posted by taydin View Post
    It looks like I can get the Asimeto dial bore gauge (50 - 160mm range) for a not so bad price here: Below is the link:

    http://www.asimeto.com/Products/Holt...p?ProductID=89

    But looking at the tip of this, I am confused. Will I be able to use this and my 50 - 75mm micrometer to measure the bearing seat? Or do I need a reference ring with 52mm ID to compare against?
    The linked instrument offers a lot of range in one instrument. However it will be at least as hard to use as a telescoping gage. Telescoping gages are like getting to Carnegie Hall- practice, practice practice. get a set and some known diammeters, like old bearing inner races or such. Practice until you can repeat the proper number reliably. You will be surprised at how well they can be used to measure .0005 easily and .0002 with practice. They look awkward but with proper use they are quite accurate.

    Leave a comment:


  • Gordon DK
    replied
    Originally posted by taydin View Post
    I am currently making seats for 8 bearings, like the ones below. Made the first one, but really struggled with measuring using my caliper. I needed to spend several minutes seating the caliper properly, getting the right feeling about the caliper position and reading the dimension. This first one ended up being a nice tight fit.

    So my question is, will buying an ID micrometer make things easier? Based on how those look, it seems I will still need to spend several minutes positioning the mic to the hole, getting that right feeling and making the measurement.

    This is my first post so here goes.

    Measuring bores intended for bearings with a dial or digital caliper is close to suicide and with a vernier caliper should be against the law.

    A 3 point digital bore micrometer is of course best but a two point micrometer such as Mitutoyo # 145-185 (5 - 30mm) is preferable to a caliper.

    I haven't read all the posts but I'm sure some must have written the same.

    Gordon

    Leave a comment:


  • Boucher
    replied
    It is easy to make a tapered plug gauge. There were several recommendations for Go/No Go gauges in the early postings in this thread. I recently bought an internal micrometer and it is not much better in my hands than the Digital calipers that I was using previously. That may improve with experience and familiarity. Take a cylindrical plug about .010 oversize and turn the outside down at a shallow angle to make a tapered plug that is .006 undersize on the small end. This will measure the bore size accurately and consistently. A .001 shrink fit on parts this size is easy. I put the Outside piece in the oven set at 200°F and the bearing in the freezer for ten minutes and they will slip together. A dedicated tapered gauge will work better and easier for this size range than the more sophisticated measuring devices. For small cuts I use a sharp HSS bit to get within .001 and file or sand to get closer.

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  • loose nut
    replied
    Originally posted by Jaakko Fagerlund View Post
    he can't use them to shave off 0.01's off millimeters at a time.
    If he cant shave off 0.01 MM then how would he do with a really small dim. like 0.0004"

    Leave a comment:


  • RLWP
    replied
    Once upon a time (well before I was born before you ask) engineers would check large cylinder bores with a bit of rod with a point filed on each end. You would put the rod across the diameter and move it from side to side around the circumference to see how much it would move. If you go back and think about my 1/8" spring bow calipers in a 1" bore example (0.004"), the pointy rods were incredibly accurate

    Have we missed a measuring method?

    Richard

    Leave a comment:


  • JCHannum
    replied
    Spring calipers are frequently used for ID measurement and, used properly are just as accurate as telescoping gages. The problem of their square faces is easily addressed by lightly grinding or filing a radius on the tips. This is a common modification. Spring calipers are a basic tool and are frequently modified to suit a particular function.

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  • Toolguy
    replied
    Sometimes if the situation is appropriate, I will expand an adjustable parallel tightly in a bore with one end sticking out and mike across diagonal corners.

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  • Jaakko Fagerlund
    replied
    Originally posted by RLWP View Post
    Being ludicrous for a moment, If the bore were 1" diameter, and the calipers had a width of 1/8", the error would be .004" on the diameter

    I don't have any calipers anywhere near as crude as that, or measure bores that small with them
    The flats are still not an issue when using calipers to transfer the ID of the bore to an OD measurement. The flats are nottouching the bore, so you don't measure across the flats.

    Anyone need a picture?

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  • RLWP
    replied
    Changed my mind

    Richard
    Last edited by RLWP; 02-01-2013, 04:20 PM.

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