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  • Internal Taper Measuring Question

    I am boring some internal tapers.

    Now measuring the small end, both ends are accessible, is simple but the large end is a problem. You can't use a caliper as it won't touch exactly on the end and then you have a false reading. 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.

    I can see that when machinists, pro or amateur, go to hell that is what happens to us. Spending all eternity trying to get the top slide set to the right angle and never getting it right.
    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

  • #2
    Originally posted by loose nut View Post
    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.
    Sure, after the DRO tells you what the current angle is, mount a sensitive digital compass on top of the compound and use that to offset the
    number of degrees required to get you to your goal. Surely someone makes an app so you can do that with a cell phone.
    Location: Long Island, N.Y.

    Comment


    • #3
      Originally posted by loose nut View Post
      I am boring some internal tapers.

      Now measuring the small end, both ends are accessible, is simple but the large end is a problem. You can't use a caliper as it won't touch exactly on the end and then you have a false reading. 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.

      I can see that when machinists, pro or amateur, go to hell that is what happens to us. Spending all eternity trying to get the top slide set to the right angle and never getting it right.
      You use a sine bar and dial in the compound. Depending on your lathe you might have to get creative to set it up. Might end up looking quite rube goldberg ish, but if it works, it works.

      To measure the big end, use different sized ball bearings and depth mic off the face. Do some math, and you can figure out your taper. If you have the mating male part, you're way ahead of the game, as you can just check directly by bluing and checking the fit.

      Comment


      • #4
        If you have the male part or a correct female part you can put that in a collet or 4 jaw chuck and indicate it to run true. Then put a mag base dial indicator on the compound slide and adjust the slide so it reads zero all along the taper.
        Kansas City area

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        • #5
          Use a dial indicator (like a Bestest) mounted to the carriage to check taper over any portion of the hole. No need to touch the cross slide angle.
          12" x 35" Logan 2557V lathe
          Index "Super 55" mill
          18" Vectrax vertical bandsaw
          7" x 10" Vectrax mitering bandsaw
          24" State disc sander

          Comment


          • #6
            An indicator gives a good hint you can probably run with, but if you are talking how to check a part its not reliable as there are no guaranties its dead at the centre height. If you're not on centre with a taper, either the tool or indicator, you'll get a result different than you are expecting.
            in Toronto Ontario - where are you?

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            • #7
              It doesn't have to be centered. You're just moving the carriage.
              12" x 35" Logan 2557V lathe
              Index "Super 55" mill
              18" Vectrax vertical bandsaw
              7" x 10" Vectrax mitering bandsaw
              24" State disc sander

              Comment


              • #8
                Originally posted by ezduzit View Post
                It doesn't have to be centered. You're just moving the carriage.
                ???? maybe I'm not understanding what you are proposing, but the indicator needle does have to be at centre height to reliably measure the taper
                Last edited by Mcgyver; 11-12-2017, 03:01 PM.
                in Toronto Ontario - where are you?

                Comment


                • #9
                  Originally posted by Mcgyver View Post
                  ???? maybe I'm not understanding what you are proposing, but the indicator needle does have to be at centre height to reliably measure the taper
                  Yep, it's critical that the indicator finger be at center height just like Mcgyver is saying. Lining it up by eye to a center in the tail post SHOULD be good enough. But do it fairly critically and with a magnifying glass if the old eyes aren't what they used to be.

                  I've done a few different tapers in my lathe over the years now and using a known good item with the taper on the outside and a test gauge to set the compound for zero runout along the length has worked out well.

                  I did find that even with all this that some Morse Tapers I did needed a touch up using a felt pen, an adapter socket and some light work with a file. But this went smoothly and the result were tapers that pinched in nicely with hardly any snap to the insertion.

                  I think the worst would be a taper for an ER chuck. The collets are too springy to use as a master for setting the angle unless they are "sprung" over something like a piece of proper size drill rod. And then I wouldn't be sure that the collet was not spread more than what is nominal for it or that it was seated correctly along the full length.
                  Chilliwack BC, Canada

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                  • #10
                    By "it" I was referring to the workpiece. ie there's no reason to check runout in the chuck as that doesn't move. Yes, of course you center the needle on the workpiece. But then you simply run the carriage back and forth to check taper.
                    12" x 35" Logan 2557V lathe
                    Index "Super 55" mill
                    18" Vectrax vertical bandsaw
                    7" x 10" Vectrax mitering bandsaw
                    24" State disc sander

                    Comment


                    • #11
                      Originally posted by ezduzit View Post
                      Yes, of course you center the needle on the workpiece. But then you simply run the carriage back and forth to check taper.
                      So was I. that the indicator needle, (a dial test indicator btw not a test indicator which is the one with a plunger) needs to be on centre height is what I said. Also as I said, its probably good enough to go to machine something, but its a poor way to check a part as you don't likely have a way of getting the needle exactly on centre, unless you've a Y axis to sweep the indicator. Not being able to verify you're on centre means you won't know whats creating the reading -good/bad part or needle slightly up/down from centre. He's also using the compound not a taper attachment.

                      imo the best/fastest set up is to rig a way to sweep the indicator, put a know good male one between centres (make and check it on the surface plate if you don't have one), tweak the compound or taper attachment until the indicator sweeps zero out. The compound or taper attachment is now at the angle of taper. So long as your boring bar is on centre, you'll get a perfect taper....check with thinly applied blue on a male of known quality.
                      Last edited by Mcgyver; 11-12-2017, 05:00 PM.
                      in Toronto Ontario - where are you?

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                      • #12
                        Originally posted by Mcgyver View Post
                        ???? maybe I'm not understanding what you are proposing, but the indicator needle does have to be at centre height to reliably measure the taper
                        Not really..... you just have to CONTACT there. Use a plunger type with narrow (but long vertically) "foot", on a male taper that fits the recess. Much nicer than fiddling forever with the indicator.

                        If no male taper, OK, you are stuck with fiddling down in the hole.....
                        Last edited by J Tiers; 11-12-2017, 05:06 PM.
                        CNC machines only go through the motions

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                        • #13
                          The inspection method uses a couple of precision balls, horstman is what we had but there are others, the balls fit in the taper, measure the first depth, then the second depth, there's som trig to work out the diameter at the contact points, you have the distance between, bit more trig, job done, the bore is verified as straight by using a clock, I have all the methods in my old note book from tech college, I can scan them and send them if you like, though Google inspection of tapered bores with precision balls would probably bring up the method,
                          Mark
                          Here's one haven watched it btw
                          https://youtu.be/CVezGPmP0Ck
                          Last edited by boslab; 11-12-2017, 05:09 PM.

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                          • #14
                            The two ball (from ball bearings) is the easiest in my opinion. The small one should be near the small end and the larger so that the surface is a bit below the end of the material. With the known diameter of the two balls and the difference of the depth to their surfaces it calculates very easy.
                            ...lew...

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                            • #15
                              Originally posted by J Tiers View Post
                              Not really..... you just have to CONTACT there. .
                              I've been incorrectly calling the contact point (what I meant and should have said) the needle, duh, I agree there is no requirement for the needle to be on zero. Either way, its not a good approach to checking parts.
                              in Toronto Ontario - where are you?

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