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Internal Taper Measuring Question

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  • loose nut
    replied
    A better way to set the top slide for a taper AND how to measure the large end hole diam.

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  • neshkoro
    replied
    Are you trying to set the compound or measure the taper? I read the answers and got lost.


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  • loose nut
    replied
    To damage my "expensive" Digimatic caliper or not to damage my "expensive" Digimatic caliper, that is the question. Worth thinking about.

    Alas poor yogurt I knew you well.

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  • Edwin Dirnbeck
    replied
    Originally posted by TGTool View Post
    The taper would have to be dead sharp at the large end. If it's rounded or a burr around the hole it would move the apparent diameter down or up the stub you're measuring.
    Here is how I measured many taper I mean hundreds The Caliper projection should be undercut and the front of the Caliper should be dead sharp


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  • TGTool
    replied
    Originally posted by loose nut View Post
    Ok that's simple enough. Thanks.

    Would turning a steep stub taper, bluing it (or marker might be better) then putting it into the large end hole and twisting it to leave a mark so that the diam. at the mark could be measured with a caliper, be accurate enough for everyday jobs? I heard about this method but have not tried it.
    The taper would have to be dead sharp at the large end. If it's rounded or a burr around the hole it would move the apparent diameter down or up the stub you're measuring.

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  • loose nut
    replied
    Originally posted by Edwin Dirnbeck View Post
    I have been earning my living doing it this way for 60 years it is the fastest and easiest method that I have found


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    Ok that's simple enough. Thanks.

    Would turning a steep stub taper, bluing it (or marker might be better) then putting it into the large end hole and twisting it to leave a mark so that the diam. at the mark could be measured with a caliper, be accurate enough for everyday jobs? I heard about this method but have not tried it.

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  • dian
    replied
    rich, i didnt get no. 2.

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  • Edwin Dirnbeck
    replied
    More options

    Originally posted by Erich View Post
    You can also use Edwin's method on the side of the tailstock ram.
    Yes indeed. any machined surface that is parallel with or perpendicular to the ways can be used. Also you can get a little
    better accuracy if you use 2 or 3 inch compound travel.Just double or triple your indicater movement value. JUST REMEMBER WHEN USEING THE COMPOUND TRAVEL METHOD ,USE THE SIN YES THE SIN OFTHE ANGLE. Good luck Edwin Dirnbeck

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  • Erich
    replied
    You can also use Edwin's method on the side of the tailstock ram.

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  • Edwin Dirnbeck
    replied
    For angles closer to 90°


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  • Edwin Dirnbeck
    replied
    I have been earning my living doing it this way for 60 years it is the fastest and easiest method that I have found


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  • Edwin Dirnbeck
    replied
    I have been earning my living doing it this way for 60 years this is the fastest and easiest method that I have found[IMG]]


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  • Edwin Dirnbeck
    replied
    I've been earning my living doing it this way for 60 years this is the fastest and easiest method that I have found[IMG]


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    Last edited by Edwin Dirnbeck; 11-13-2017, 11:11 AM.

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  • Rich Carlstedt
    replied
    Originally posted by loose nut View Post
    .................................................. .......................... So is the only way to do it, turn a a male taper and shove it into the female taper and then measure across the interface between the too???
    Is there a simpler way???............................................ ....................................

    Part 2.

    Adjusting the top slide to the right taper. I can measure the taper angle accurately with a DRO function but then to set the angle you loosen and tap the slide, then remeasure and repeat the tapping and so on and so on etc. always missing the mark. Is there a way to adjust the top slide and get it correct without the trial and error method.........................................
    Yes Loose Nut----There are other ways.
    1.
    You need to make a taper measurement tool...and it's rather simple...let me throw out some imaginary numbers
    say the tapered bore goes from 9/16 to 13 /16 . You want two disks mounted on a threaded rod.
    get a 1/4 inch threaded rod, say 4 inches long and CAREFULLY center-drill both ends. now make two round disks that are bored/drilled to slide on the threaded rod, but no slop .. but first mount them on a threaded rod stub in the lathe and turn them to diameter ( 5/8 and 3/4 ie) leaving SHARP EDGES ( BUT NO BURR ) they can be 1/4'"thick, or 1/8" or whatever, just have a clean sharp edge.
    Take 4 nuts and put two in the middle of the rod, then place the small disk on one end and capture it with a nut on the end and one of the middle nuts,
    Place the tool into the bore to be measured, and the small disk will bottom on the taper,. now place the larger disk in the bore and follow it with a nutand snug it up against the large disk. Remove the tool and run the middle nut up to the big disk.. You now have a accurate measurement by measuring the front edge distance between the disks. You ,may want to play with it a bit, but you get the drift. Having the rod center-drilled allows you to use it between centers
    This tool is neat, because you get to measure a bore you wish to match or the one you are working on and it can be used to set your tool-slide as well or between centers.

    2.
    For setting tapers easily, you need to rework your tool-slide ( On some lathes !) I have on mine.
    Take the tool-slide off. You can mill it, but grinding is better. Set the positive side of the dovetail surface on a dowel pin and grind the outside parrallel and perpendicular to the positive side, then flip and grind the other side, Now you have a tool-slide with perfectly parrallel surfaces to the way surface.
    To do a taper, I clamp a ground piece of flat stock ( say 1/4 x 6 x 6 ) to the side of the slide with a C clamp and swivel it against the form which is chucked in the lathe . My tool-slide EXACTLY matches the taper as I clamp the slide. Remove the plate and cut your work......so fast and no hunting at all.

    Hint #3 if you do not want to do # 2 above, clamp a temporary bar of about 18" in length to the tool slide. use the end for leverage to get very small movement of the slide. keeps the slide from jumping too !

    Rich

    I like my disks to be about 3/8" to 1/2" thick. Part off drill rod and clean the OD as size means nothing !

    Be careful using aluminum (no-no) as it can wedge and give a false reading
    Last edited by Rich Carlstedt; 11-12-2017, 09:21 PM.

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  • Ohio Mike
    replied
    Use an indicator to check the change in diameter over a known distance. To do this the easiest way is to center the indicator in the bottom of the taper. Run the cross slide in and out and the smallest reading on the indicator is the lowest point aka "on center". A Starrett 670 hole attachment would be handy here. Then run the carriage in/out with 2nd indicator on the bed. You now have the change in radius over a known distance.

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