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  • Turning a Morse taper...

    I managed turn a Morse taper to make an arbor using the tailstock offset method. The task raised a couple of questions.

    How does one calculate the effective length of a bar between centres? I measured as best I could and allowed 2mm then used my DTO to ensure the tailstock the right amount. The result was close but it still wobbled in the socket, I was able to correct by using a DTO mounted on the carriage to measure the taper between taking gnat's whisker cuts.

    The second question is how does a home shopper possibly measure to the standards which have 3 or 4 decimal places? Or should we just shoot for 1:20?

    Thanks..

  • #2
    The effective distance between centres need (should) not be used.

    Put two (pencil) marks 100mm or 50mm or 75mm to suit apart on the job (restore as necessary).

    There is more than one morse taper in terms of angle and "taper per inch" - just a slight taper differenece.

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    • #3
      Originally posted by The Artful Bodger
      The second question is how does a home shopper possibly measure to the standards which have 3 or 4 decimal places? Or should we just shoot for 1:20?

      Thanks..
      With his surface plate, sinebar, gauge blocks, surface gauge and indicator...

      or he just blues up the part and shoves it into a known good socket to see the fit...
      Precision takes time.

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      • #4

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        • #5
          Has been covered a few time here. Chuck up a tapered shaft that you want to duplicate. Adjust your taper setup so sweeping a dial indicator from end to end results in zero deflection. Replace the dummy shaft with a blank and machine.

          Comment


          • #6
            When using the offset tailstock method for taper turning, you cannot use an existing taper to set up your work. The overall length must be determined and the tailstock set over the proper amount to give the desired taper per length.

            The hooker though is that the true overall length is hidden somewhere in the centers drilled in the ends of the workpiece and is slightly shorter than the actual length of the workpiece. This can be overcome by some esoteric calculations, or make the piece a bit over length and fit by trial and re-adjusting the tailstock on the final passes.

            Don't feel too bad, the reason Morse tapers have such odd tapers, and no standard taper between the various sizes is that Mr. Morse couldn't get it just right either.
            Jim H.

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            • #7
              The most effective way seems to be to set up between centers WITHOUT a setover, and use the compound to cut the taper.

              While many compounds do not have quite enough travel for a full MT3, I have found that one can cut as much as travel will allow, and just undercut the small remaining area, leaving the length correct for the drawbar or ejection tang.

              The length of taper you can cut is almost surely enough, unless your compound is VERY short on travel. It isn't generally necessary to try to reset exactly enough to cut the taper in two sections just for the sake of having the full length.

              The small end cannot add as much "grip" and torque-transmission as the large end. And, if you get the small end a tiny amount larger, even if it seems to "fit", you may reduce the torque capability by taking more of the friction on the smaller diameter.

              If you need to make an MT4, well, you should get a taper attachment....
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #8
                I'd hate to have to make a Morse taper from dimensions alone. I'd do as J Tiers suggests -- use the compound. Set the angle by putting an existing Morse taper between centers (NOT offset) and using a dial indicator on the compound, traverse the taper adjusting the angle of the compound until the indicator doesn't move. Cut the taper almost to final size using the compound, then when you're close start using high-spot blue and a test socket to tweak the final finish cuts.

                If you have to do it between centers, do basically the same thing: get it close, then do final tweaking by checking with high-spot blue and a test socket.

                BTW, for offset centers a good trick is to use female centers (hold a stub of bar and center drill it), then mount the work by capturing ball bearings between the ends of the work and the headstock and tailstock centers.
                ----------
                Try to make a living, not a killing. -- Utah Phillips
                Don't believe everything you know. -- Bumper sticker
                Everybody is ignorant, only on different subjects. -- Will Rogers
                There are lots of people who mistake their imagination for their memory. - Josh Billings
                Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                Don't own anything you have to feed or paint. - Hood River Blackie

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                • #9
                  So, with the easy availability of professionally made Morse taper blanks why would anyone go to the trouble of turning one?

                  Okay, I can understand wanting the challenge, but in most cases these are to be used in a taper on a presumably valuable machine. Too much risk for me of damaging the machine's taper with a less than perfect fit of a home-made taper.

                  Comment


                  • #10
                    Originally posted by DR
                    So, with the easy availability of professionally made Morse taper blanks why would anyone go to the trouble of turning one?

                    Okay, I can understand wanting the challenge, but in most cases these are to be used in a taper on a presumably valuable machine. Too much risk for me of damaging the machine's taper with a less than perfect fit of a home-made taper.
                    My thoughts exactly. There are enough challenges out there without re-inventing the wheel...
                    Keith
                    __________________________
                    Just one project too many--that's what finally got him...

                    Comment


                    • #11
                      Here is some more info on turning Morse tapersl

                      http://neme-s.org/Morse%20Tapers.xls shows stack height for setting up a sine bar for Morse tapers.
                      Errol Groff

                      New England Model Engineering Society
                      http://neme-s.org/

                      YouTube channel: http://www.youtube.com/user/GroffErrol?feature=mhee

                      Comment


                      • #12
                        Thanks for the comments everyone.....

                        I cannot use the compound as that requires the compound to be close to parallel to the work piece causing the handle to foul the tail stock, or the chuck/faceplate if I tried from the other end. It puzzles me how anyone can do it but I guess it can be done with the tail stock quil wound right out, overlong work piece used, or a long tool stick out. Easy if the workpiece is not supported.

                        If I could find the length of the work piece between centres I could confidently set the tail stock over then 'do it right, do it once'.

                        There is another complication with my lathe in that I cannot adjust the tail stock set over without releasing the clamp which results in a lot of messing around when trying to make small adjustments.

                        I have used the method of mounting an existing tool between centres to set the compound but (as mentioned) I run into problems using the compound especially when making a Morse Taper 1 dead centre for my old Drummond lathe.

                        For me this is a challenge and/or learning experience. I am not in production but I am a retired olde pharte playing in his shed and hopefully preserving brain and other physical capabilities by doing so.


                        SGW, thanks for the ball bearing scheme as that one gives an easy and accurate method of determining effective length (centre of ball to centre of ball).

                        BTW, the method I use to check the taper is to mount a DTO on the back of the cross slide. I move the carriage until the wheel graduations show zero then move the cross slide out to bring the DTO in contact, zero the DTO then wind the carriage 30mm and check the DTO has moved 0.75mm (actual numbers subject to confirmation! ) This is the most accurate method I have in my home shop.

                        Comment


                        • #13
                          Originally posted by DR
                          So, with the easy availability of professionally made Morse taper blanks why would anyone go to the trouble of turning one?
                          Because its a relatively easy (though it requires a bit of care), cheap, and quick task to do. If youre reasonably careful, and not one of those that seats tapers with a rubber mallet, there is little worry over damaging the machine taper. One could also eliminate the possibility of machine harm by checking using a good known taper socket and not the machine itself.

                          Call me crazy, but I also would rather learn to do something now when I want to (such as this instance of AB's) rather than later when I may need to make a special tool to finish another project. Projects are nice. Projects within projects suck big time.
                          "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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                          • #14
                            Why use the tail-stock at all? If its not needed - get it out of the way.

                            Turn the MT blank progressively from a solid in the 3 or 4 jaw chuck.

                            The blank will be sufficiently "stiff/rigid" to use your compound to turn the taper.

                            The compound top-slide can be set by clamping or holding a good protactor to the top slide using the face of the chuck as a reference:


                            Or use a bevel gauge pre-set from a protractor:




                            And "fine tune" your angle with a good indicator on the compound slide:

                            Comment


                            • #15
                              Originally posted by DR
                              So, with the easy availability of professionally made Morse taper blanks why would anyone go to the trouble of turning one?
                              Because you want something attached to that taper that is concentric, solid, and which is not readily available.....

                              Milling machine arbors with, say, an MT3 taper..... Shell end mill arbors for MT3 (the one source never has stock)..... specialty tooling pieces of various sorts..... The list goes on.

                              Buying a tapered "something else" and then grafting the taper portion onto an arbor shank, etc, results in a dubious hybrid part that may let go on you when you least want it to. And may be impractical for any of many possible reasons.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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