What is the best method to measure this hole
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  1. #1
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    Default What is the best method to measure this hole

    How do you measure the hole with out removing the bar?image_20190808_142205_1565299393557.jpg

    I'm asking for a buddy
    Thanks Ron

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    Measure the bar and add the telescoping gauge readings to each side of the bar. Not great, but better than eyeball. If the bar setup is any good, you should be able to withdraw the bar and measure and put the bar back. Depending on the drive and bushing setups, you might not get back on the exact same centerline, but the size will stay the same if you don't disturb the cutter. Hopefully the cutter increment for the next cut is bigger than the centerline shift from putting the bushings back if you had to move the bushings. DTI sweep to the rescue on that issue.

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    make a series of plug gages with relief for bar and cutter
    how tight of tolerances ?

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    It looks like there is enough room to use an internal spring caliper and transfer to a micrometer. Old school but should be able to get well within earth moving equipment tolerances. Takes some practice. (It looks like a earthmoving part)

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    Portable CMM, or a tape measure.

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    Carefully.

    Line boring manufacturers have complete lines of measuring equipment they sell with their machines. York and Climax are the better manufacturers. Have your buddy look at some of their youtube stuff for measuring equipment.

    Some of the methods I have used include spring calipers, telescope gages in tool holes in the bar, measuring the gap between the bar and bore (be careful of bar runout), and fitting a near size tapered hollow pin on the bar before assembly. I have also used a special bore gage that clears the bar. No one method works all the time, so the more methods the better.

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    Quote Originally Posted by Larry Dickman View Post
    Portable CMM, or a tape measure.
    But is it really one of "Those" jobs...

    It obviously looks like its on some tractor that is beat to hell..

    I'd make a GO gage, with a few steps. Maybe .005, .010, and 20 under..
    Then hog out the guts so it will fit around the boring bar..

    It doesn't look like it will ever have to fly, so as long as the bearing
    stays where it is supposed to and does what its supposed to, who cares..

    This is a "Make it Work" job.. Not a "To Print" job..

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    Quote Originally Posted by howieranger View Post
    It looks like there is enough room to use an internal spring caliper and transfer to a micrometer. Old school but should be able to get well within earth moving equipment tolerances. Takes some practice. (It looks like a earthmoving part)
    +1

    With some practice you can do +/- 0.001 with this. Joe M would say, 0.001 TIR!

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    1) Direct measure: 24", 36" or 42" vernier caliper to get long, stiff jaws. Pair of bearing balls at the tips so I can work at an angle. Outside Mic to confirm. Multiple readings off marked locations. Check for error and variation.

    2) Indirect measure: Flexbar Indi-Cal with DI mounted. Measure left and right bar to wall, more than one place off Sharpie-marked locations. Outside mic the bar, same set of locations. Do the addition, Check for error and variation.

    If I did not already have the verniers and a pair of Indi-Cals, then:

    Attach outward pins to an OD spring caliper if my ID one won't clear the bar, 'coz it looks as if it may not, and I no longer have but one or two sizes.

    ELSE

    Fab a fixture that can transfer stable measurement to an existing mic.

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    These snap gages can be used in an empty hole in the bar. One end is spring loaded so you when you release it, both ends get pushed against the bore. They are good to a half thou.

    dsc01178-small-.jpg

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    Quote Originally Posted by slowmotion View Post
    These snap gages can be used in an empty hole in the bar. One end is spring loaded so you when you release it, both ends get pushed against the bore. They are good to a half thou.

    dsc01178-small-.jpg
    Learn what a snap gage is:


    L

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    Quote Originally Posted by slowmotion View Post
    These snap gages can be used in an empty hole in the bar. One end is spring loaded so you when you release it, both ends get pushed against the bore. They are good to a half thou.

    dsc01178-small-.jpg
    "Telescoping gages", you mean. Asymmetrical ones in this case, is all.

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    Default What is the best method to measure this hole

    How is a telescoping gauge going to work with the boring bar in the way?

    Edit: unless you mean like mentioned above. Measure gap on both sides of bar and add bar diameter. Make potential for 3x any inaccuracies
    Sent from my iPhone using Tapatalk Pro

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    Internal calipers and a micrometer.
    Bill D

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    Quote Originally Posted by ripperj View Post
    How is a telescoping gauge going to work with the boring bar in the way?

    Edit: unless you mean like mentioned above. Measure gap on both sides of bar and add bar diameter. Make potential for 3x any inaccuracies
    Poster of it mentioned operating it through an existing hole in the boring bar. Balanced (looking) types can sometimes do that, too.

    My approach, and those of most others, does not expect handy holes, nor need such.

    "Stacking" erorr is wot it is.

    One counter to it is tedious patience, multiple readings taken and reviewed such that even marginal metrology (story of my life, etc.) serves.

    Owning two Indi-Cals and a dozen or so DI, the DI substitutes for dodgy repeatability of "feel". Ve gang too soon Elt, und too late rich mit stoff.

    Care in use and multiple test points are still required, but they take less time. If the bar were more easily asided and restored, I'd use an ignorant bore gage - faster-yet.

    But if the bar could...etc. so would the OP have done, yah!


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    Another method would be to use a Pi tape.

    Sent from my SM-G930P using Tapatalk

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    Quote Originally Posted by Silent_Man View Post
    Another method would be to use a Pi tape.

    Sent from my SM-G930P using Tapatalk
    If you have ever done this, please explain. How do you push the Pi tape in the hole and get it squared up, and still read the markings?

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    Well the OP question was "best"...
    If i could not pull the bar (should repeat)
    I would go with this gauge.....Part of the kit for my "BC4 Berco" line boring machine.

    Adjustable for different sized bores. Set size using ring gauge or micrometer.
    Has two centering points to center in the bore and one moving finger that is connected to the dial gauge....

    Opening clears the bar fingers read the bore...






    Cheers Ross

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    I like that Berco gage.

    These work good too.

    Internal Caliper Gage | 57-015-072 | Travers Tool Co., Inc.

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    Quote Originally Posted by lazz View Post
    How do you measure the hole with out removing the bar?image_20190808_142205_1565299393557.jpg

    I'm asking for a buddy
    Thanks Ron
    Depends on the tolerance or how accurately you want to measure.


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