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ID micrometer, is it worth buying one?

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  • GadgetBuilder
    replied
    There's a picture of a bottoming lap on my site if you scroll down here:
    http://www.gadgetbuilder.com/Lapping.html

    Laps need to be shorter than the item being lapped (to avoid bellmouth) so you'd need to make an appropriate lap, something like the bottoming lap shown with the brass turned down except for a 5mm shoulder at the end which would be the active section. Shop made laps don't look as slick as commercial laps but they work fine. Rollie Gaucher is a master of this technique - his shop made laps aren't necessarily pretty but they work well. Some pictures here:
    http://neme-s.org/2008_February_Meet...ly_meeting.htm

    You could make a lap holder from steel: solder a 5mm or so wide strip of sheet brass on the end, add setscrews to adjust, and have a workable bottoming lap without too much effort. I haven't actually made a lap like this but it's how I would approach the task you're working on - seems worth a try since it isn't too difficult. I've had good results with lapping when working to close tolerances, so much so that when working under a thou I often try to figure out if it can be lapped.

    Monroe is the next town south of us, we often eat at the El Coyote Mexican restaurant there. We have a friend who moved back to Izmir, Turkey after her husband passed, she'll be visiting here in April. The world is smaller than we realize.

    John

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  • taydin
    replied
    Originally posted by Jaakko Fagerlund View Post
    I would say that the result you got is typical for digital calipers, they are almost always 0.01..0.02 mm off and the outside jaws vs. inside jaws don't zero out the same. If you want to zero out the outside jaws, you have to use a ring to do it, but the zero reference is then at that diameter, so don't get confused with your readings.
    Yup, well within the manufacturer's stated accuracy limits. But I really liked the fact that I can make repeated measurements and get the same result. Not that this is a replacement for a mic, but it is definitely better than my Mitutoyo vernier caliper. What I don't like about it is the refresh rate of the display is very slow.
    Last edited by taydin; 03-09-2013, 05:05 AM.

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  • taydin
    replied
    Originally posted by GadgetBuilder View Post
    Have you considered making a bottoming lap and lapping the hole to size? Seems it would address several issues: holes may not be as round as we expect (surprisingly difficult to measure), surface finish makes accurate measurement challenging (and also affects fit), boring in small increments is difficult while laps naturally work in small (and predictable) increments.
    Couldn't find anyting about a bottoming lap at google. Is this a shaft with sandpaper mounted on it, where one end of the sandpaper is flying free?

    BTW, Newtown, CT ... I have worked in Monroe, CT, right across the Clearwaters Restaurant for six years Newtown is a beautiful town!

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  • GadgetBuilder
    replied
    Have you considered making a bottoming lap and lapping the hole to size? Seems it would address several issues: holes may not be as round as we expect (surprisingly difficult to measure), surface finish makes accurate measurement challenging (and also affects fit), boring in small increments is difficult while laps naturally work in small (and predictable) increments.

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  • Jaakko Fagerlund
    replied
    Originally posted by taydin View Post
    Well, how about this one? As Dave suggested, I have done 5 measurements using the caliper. I made sure the caliper is parallel to the surface of the part and found the maximum by shifting back and forth. Everytime, I got a result of 51.99mm or 52.00mm. So there is a discrepancy between the upper jaws and the lower jaws of this caliper. Don't have a reference ring to qualify the upper jaws. How would you interpret this?
    I would say that the result you got is typical for digital calipers, they are almost always 0.01..0.02 mm off and the outside jaws vs. inside jaws don't zero out the same. If you want to zero out the outside jaws, you have to use a ring to do it, but the zero reference is then at that diameter, so don't get confused with your readings.

    And just because of these variances I never trust (digital) calipers as such, especially for ID measurement, but insead use an outside mic to get the reading and the caliper itself just provides safety for the 0.5 mm error that is always lurking behind the corner when using a mic.

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  • taydin
    replied
    I am having too much fun today I closed the caliper, zeroed it, opened it to 50.00mm and locked it using the screw. Then I used my micrometer to measure the inner jaws. 50.01mm. So there is a slight difference between the upper and lower jaws, but it's all within the accuracy of a typical caliper, which is stated as 0.02 or 0.03mm in most models...

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  • taydin
    replied
    Originally posted by becksmachine View Post
    Now to the fun part. When you measured your bearing bore you came up twice with a number that should have let the bearing fall into the hole. If I remember correctly you said that you had to drive the bearing in with a hammer? In my experience, a ball bearing is one step removed from a master or standard.
    Dave, I definitely had to hammer this in. But I have looked at the inner edge under the microscope, and it is quite rough. So it might be that the burrs were resisting to the bearing coming in. So this definitely calls for the plan B that was suggested by some member, glue it in

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  • taydin
    replied
    Well, how about this one? As Dave suggested, I have done 5 measurements using the caliper. I made sure the caliper is parallel to the surface of the part and found the maximum by shifting back and forth. Everytime, I got a result of 51.99mm or 52.00mm. So there is a discrepancy between the upper jaws and the lower jaws of this caliper. Don't have a reference ring to qualify the upper jaws. How would you interpret this?

    Leave a comment:


  • Jaakko Fagerlund
    replied
    Originally posted by becksmachine View Post
    Just for fun, try measuring the diameter of the hole directly with the id jaws of the digital caliper as is advocated by so many members here. Try it 3 or five times to see if you can come up with a consistent result.
    Don't even need digitals for that one, if it has a screw lock and you have the outside mic at hand.

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  • becksmachine
    replied
    Hi Taydin, I would like to compliment you on your habit of always following up on your posts, thank you!

    Speaking strictly for myself, it makes me much more likely to want to take the time to offer advice/help if I know I will hear the final result, either good or bad.

    Wow, does it really take a month to get simple stuff shipped to you? How do you stand the anticipation?

    Now to the fun part. When you measured your bearing bore you came up twice with a number that should have let the bearing fall into the hole. If I remember correctly you said that you had to drive the bearing in with a hammer? In my experience, a ball bearing is one step removed from a master or standard.

    Just for fun, try measuring the diameter of the hole directly with the id jaws of the digital caliper as is advocated by so many members here. Try it 3 or five times to see if you can come up with a consistent result.

    Dave

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  • taydin
    replied
    My telescoping gages have finally arrived!



    Immediately set out to measure the quality of my bearing seat using a micrometer. Result: 52.03mm



    Just for fun, repeated the measurement using a 30$ digital caliper. 52.02mm! I even measured the 50mm reference rod, and again, it was only off by 0.01mm. I will continue using the micrometer for these types of measurements, but this cheap digital is pretty good!



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  • dian
    replied
    insize: weird company, i wrote them an email asking for prices, didn get any answer.

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  • Mcgyver
    replied
    Originally posted by Gordon DK View Post
    Bow or curtsy - up to you
    No approprite response comes to mind that wouldn`t be offensive to the rest of the members.

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  • Gordon DK
    replied
    Originally posted by Mcgyver View Post
    so are we supposed to bow when BF enters?
    Bow or curtsy - up to you

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  • Black Forest
    replied
    Originally posted by Mcgyver View Post
    so are we supposed to bow when BF enters?
    NO NO I try to keep a low profile on this site. And you Mcgyver must not in my presence either. But A.K. Boomer must bow and kiss my feet.

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