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  • #31
    Thanks for all of the input,
    Here's the progress report so far. I had a spacer ring on hand that I used to spin the face plate on backwards and the backside ran within .001 at 8" so the threads seem to be reasonably true to the plate faces. I faced off about .500 of unnecessary length on the snout and bored the clearance for the register at .010". I deburred and cleaned everything, mounted it in the correct orientation and then spent some time turning the OD down from 8.25" to 6.2". The vendor didn't have a 6" when I ordered so I accepted the larger size so I wouldn't have to wait. Not sure I would do that again next time but it wasn't the end all. I faced the mounting surface off to provide a .150 snout for my check register and have the register diameter within a couple thou of my target size. It's going to have to call the spindle nose home for a bit and wait for some more free time for the final fit and tapped mounting holes.

    SM

    Comment


    • #32
      In case anyone is wondering if the "register" actually does have a real purpose, I say YES it does.

      Spindle threads, like virtually all threads, do not continue in full form all the way to the shoulder. So, if there is no relief at the start of the back plate threads, the thread will jam and the rear surface of the back plate will not actually contact the shoulder on the spindle. The likely outcome from this condition is a back plate and the chuck on it will not mount properly and will likely sit at an angle to the axis of the lathe. So the "register" area allows the back plate thread to NOT jam and the rear surface of the back plate will seat tight against the shoulder of the spindle.

      In other words, the "register" IS the necessary clearance needed for the thread to assemble properly.
      Paul A.
      SE Texas

      And if you look REAL close at an analog signal,
      You will find that it has discrete steps.

      Comment


      • #33
        It also provides a "lead -in" to get the chuck aligned and make it easier to start the thread. I understand from one of my shop texts that one brand had a similar space at front and back of the spindle thread. You could get the chuck onto both, then easily start the thread.
        CNC machines only go through the motions

        Comment


        • #34
          Originally posted by Paul Alciatore View Post
          In case anyone is wondering if the "register" actually does have a real purpose, I say YES it does.

          Spindle threads, like virtually all threads, do not continue in full form all the way to the shoulder. So, if there is no relief at the start of the back plate threads, the thread will jam and the rear surface of the back plate will not actually contact the shoulder on the spindle. The likely outcome from this condition is a back plate and the chuck on it will not mount properly and will likely sit at an angle to the axis of the lathe. So the "register" area allows the back plate thread to NOT jam and the rear surface of the back plate will seat tight against the shoulder of the spindle.

          In other words, the "register" IS the necessary clearance needed for the thread to assemble properly.
          Paul , In over 64 years of machine shop experience, I have never seen a threads to the shoulder as you speculated ,
          There is always a clearance area provided by the chuck/faceplate maker so the threads never run to the face of the spindle. the Lathe makers know this
          and would not do that . Your "jam " argument is without real life product . You have fallen for the old wives tale a bit with that thought .

          If this aspect of a lathe is important , and obviously Lathes have multiple chuck attachments , isn't it Logical that such an important
          specification would be known and published ? , well it isn't, because the Lathe makers know more than many Home Shop machinists
          So let me throw this challenge to you .
          Show me a lathe spec where the so called register is diameter is listed ? and while you are at it , lets look at Dividing Heads which have chucks , that must be dead nuts
          in concentricity so the Register Diameter would be important as well -
          . I am not being a smart axx, I am saying Look..--you will not find it !
          Its not there because the Registration argument is a figment of imagination
          Rich

          Edit 1. Here is a Dividing Head- Check it out
          https://www.amazon.com/Vertex-Univer...82557&sr=8-44\

          Edit 2. This discussion / argument reminds me of the Lemming Story that persists after 70 years, that Lemmings commit suicide
          (They are like field mice )
          Lemmings do not commit Suicide !, But the story lives on , and much like Lemmings is the "Register" a fairy tale
          I just wish home shoppers would know the truth .
          Last edited by Rich Carlstedt; 03-21-2021, 11:51 PM.
          Green Bay, WI

          Comment


          • #35
            Originally posted by J Tiers View Post
            It also provides a "lead -in" to get the chuck aligned and make it easier to start the thread. I understand from one of my shop texts that one brand had a similar space at front and back of the spindle thread. You could get the chuck onto both, then easily start the thread.
            Jerry, The only time the Counter bore at the start of the thread helps with starting, is IF the C'Bore is the same size as the OD of the thread itself
            Most Commercial Chucks have bigger C'bores. If you make it the same as the Thread OD, then the whole concept of machining to a Register becomes a non -entity.
            Rich
            Green Bay, WI

            Comment


            • #36
              Originally posted by Rich Carlstedt View Post
              If you happen to get a Face or Chuck Plate that was not "Faced" on the rear (LH) side of the plate ...OR
              The Plate is Too thick and you need to reface it , you must do so with force placed on the threads, else you will have a Mistake in the relationship
              of the threads to the rear face of the plate . The rear face must be perpendicular to the thread axis !
              To do this , use a piece of soft solder and wrap it around the spindle one or two turns ( Equally 360 degrees or 720 !- No extra !)
              Now spin on the plate backwards so the shoulder can be faced properly. Tighten it against the soft solder which will align it self as the threads put pressure
              on the solder and it will allow any uneven surfaces to adjust to the Helical Forces squarely. Now face
              Rich
              Neat idea using soft solder. The one time I had to clean up the back of a chuck plate I threaded it on to the spindle where I had installed a small aluminum collar. The collar had four small lead shot balls, equally spaced, epoxied on to the face that rested against the backwards mounted chuck plate. I didn't over tighten the plate, only enough to feel that it was seated. Not sure if it was more the aluminum giving way as the lead brinnelled into it or the lead mushing against the plate, but it worked. Cleaned up the face nice and square to the threads with light cuts. That's when I learned that it can not be stated strongly enough that when mounting things on threaded spindles the back (registration) face must be perpendicular to the threads. When it's not, I believe we have the single biggest cause of chucks getting "wedged" so tight on to a spindle that damage to some part of the machine occurs when attempting to remove the chuck. After I cleaned up the back of that chuck I never had to struggle with removing it again. What was frustrating is that it was a worn out 9 inch South Bend that was only used for polishing and de-burring parts. Never any heavy loads on the chuck but it seamed like that thing used to wedge in place if you just looked at it wrong.

              Comment


              • #37
                Originally posted by Rich Carlstedt View Post

                Jerry, The only time the Counter bore at the start of the thread helps with starting, is IF the C'Bore is the same size as the OD of the thread itself
                Most Commercial Chucks have bigger C'bores. If you make it the same as the Thread OD, then the whole concept of machining to a Register becomes a non -entity.
                Rich
                Nah, it helps anyhow.

                Dog point screws are a super-loose fit on the nose, but they sure help align the nose of the screw. Same deal. Just a guide that "houses" over the thread and makes it easier to get the chuck threaded on.

                If it were 100 thou radially larger, sure, but normally it is no worse than maybe 30 or maybe 40 thou oversize on the diameter
                Last edited by J Tiers; 03-22-2021, 01:59 AM.
                CNC machines only go through the motions

                Comment


                • #38
                  Rich, I am not quite sure why you are disagreeing with my post. Are you saying that the so called "register" is really not needed? If so, I challenge you to make a back plate for a threaded spindle without that feature. AND MOUNT IT. It simply will not work. Unless you do include a very big bevel or chamfer.

                  If that is not your point, then what is? Are you saying that I should not point out this reason for the feature? Why shouldn't I?

                  I will concede that it does also make the process of mounting a chuck easier. But I also suspect that this is not the original or primary reason why the first such spindle/chuck combination was made this way. The designer of that first screw-on chuck knew that the thread would not go all the way up to the shoulder so he (she?) simply allowed for that practical necessity. Or at the very least, it was added after the problem was made apparent while using that first such mount. That is all I am saying.

                  So, of course a chuck that would jam on the thread is not observed in real life. And it is the "register" that prevents this. That's why you have never seen it and probably never will. That was exactly my point.

                  As for publishing a specification for it, the only real specification that it has is that it should have some clearance but leave enough of the rear face of the back plate to mate with the face/shoulder of the spindle. This fit is so loose that hardly no one would bother to state it other than to say it should be larger than the OD of the thread used on the spindles. Actually a tighter fit would be needed if it's primary purpose was to make mounting and dismounting the chuck easier. In that case I would want a specification making it between 0.002" and, perhaps, 0.010" greater than the OD of the spindle thread. But none of the lathe makers specify that either. In fact, they do not even specify the actual OD of the spindle thread: instead they simply provide a nominal value like 1 1/2".

                  I am sorry, but the lack of a published specification does not prove that there is none.

                  And as far as a "registration" argument is concerned, just why do you think I always put the word "register" in quotation marks when I am referring to that feature of a screw mount. And I did not start that practice in this thread: I have been doing it for years. I do that precisely because I do believe the very word "register" for this feature is one that was very poorly chosen. It is misleading because it leads one to believe that it is somehow aligning something. I do not like using it but do not have another one that would be understood. If you do, I would be glad to use it in the future.



                  Originally posted by Rich Carlstedt View Post

                  Paul , In over 64 years of machine shop experience, I have never seen a threads to the shoulder as you speculated ,
                  There is always a clearance area provided by the chuck/faceplate maker so the threads never run to the face of the spindle. the Lathe makers know this
                  and would not do that . Your "jam " argument is without real life product . You have fallen for the old wives tale a bit with that thought .

                  If this aspect of a lathe is important , and obviously Lathes have multiple chuck attachments , isn't it Logical that such an important
                  specification would be known and published ? , well it isn't, because the Lathe makers know more than many Home Shop machinists
                  So let me throw this challenge to you .
                  Show me a lathe spec where the so called register is diameter is listed ? and while you are at it , lets look at Dividing Heads which have chucks , that must be dead nuts
                  in concentricity so the Register Diameter would be important as well -
                  . I am not being a smart axx, I am saying Look..--you will not find it !
                  Its not there because the Registration argument is a figment of imagination
                  Rich

                  Edit 1. Here is a Dividing Head- Check it out
                  https://www.amazon.com/Vertex-Univer...82557&sr=8-44\

                  Edit 2. This discussion / argument reminds me of the Lemming Story that persists after 70 years, that Lemmings commit suicide
                  (They are like field mice )
                  Lemmings do not commit Suicide !, But the story lives on , and much like Lemmings is the "Register" a fairy tale
                  I just wish home shoppers would know the truth .
                  Paul A.
                  SE Texas

                  And if you look REAL close at an analog signal,
                  You will find that it has discrete steps.

                  Comment


                  • #39
                    I think Rich C missed the fact that you are ascribing NO alignment action whatsoever, but ONLY a clearance to allow the chuck to screw down solidly.

                    The alternative is a recess as on Sherline, where the threads stop short of the face, and are undercut/recessed. In general as you know, and did not dispute, the unthreaded area of the chuck is an unspecified amount larger than the threads as a clearance.

                    I claim additionally that it is easier to mount a chuck with that area unthreaded than with threads all the way to the end, as would be possible with Sherline. A function like a dog-point screw, to somewhat align the threads and reduce the amount that the spindle threads may get bunged-up when mounting chucks.

                    Your point about threads to a surface is good also, that would be not only difficult, but weaker than the usual practice.
                    Last edited by J Tiers; 03-22-2021, 02:10 AM.
                    CNC machines only go through the motions

                    Comment


                    • #40
                      What a gang of angry cranky old men you are. In the time you have spent arguing over this, long ago settled, proven and accepted practice you COULD have used your minds to actually CREATE something. I am out of here,will not waste my time even reading your nonsense, David Powell,

                      Comment


                      • #41
                        Good result, Marsh, shame about all that infernal extra cast iron dust getting down to the OD. The last chuck I bought for a song on ebay, a NOS 100mm, 4" Pratt Burnerd was fitted to a spare 5" backplate and I didn't bother to match the sizes. The 6 screws are because I prefer the chuck/backplate register to be loose for fine adjustment.

                        Click image for larger version  Name:	_IGP2705.JPG Views:	0 Size:	416.1 KB ID:	1935245
                        Last edited by old mart; 03-22-2021, 10:45 AM.

                        Comment


                        • #42
                          Paul, We have no disagreement in principal. There is a "shoulder" on some threaded Spindles, not a register.
                          The very name ( register) promotes falsehood

                          David, You are right , we come across as cranky old guys , and I am sorry about that !
                          In the hope of educating newbe's, we may get carried away with personal beliefs ,opinions, and facts
                          My comments end here....and Thanks !

                          Rich
                          Green Bay, WI

                          Comment


                          • #43
                            Originally posted by David Powell View Post
                            What a gang of angry cranky old men you are. In the time you have spent arguing over this, long ago settled, proven and accepted practice you COULD have used your minds to actually CREATE something. I am out of here,will not waste my time even reading your nonsense, David Powell,
                            Old and cranky, I certainly am, but think of being unable to go near any machinery for 6 months due to covid shutdown restrictions. The museum where I do all my machining has been shut since before Christmas, and won't open till mid May.

                            Comment


                            • #44
                              Originally posted by David Powell View Post
                              What a gang of angry cranky old men you are. In the time you have spent arguing over this, long ago settled, proven and accepted practice you COULD have used your minds to actually CREATE something. I am out of here,will not waste my time even reading your nonsense, David Powell,
                              And you have just added to the total......... just sayin'

                              No anger here, SOME people can discuss, and even "argue" (which really only means to state your case, as in the "argument" that a lawyer may use) without becoming angry so long as the other party does not get nasty. It takes more equanimity than some have if people DO get straight-up nasty.

                              I have never understood the horror and repulsion some thin skinned folks, ("snowflakes" even) have about what they call an "argument".

                              But then, I'm substantially Irish in heritage, and we love discussions. An Irish person who is still talking is not angry.... it's when we shut up that you must worry.
                              Last edited by J Tiers; 03-22-2021, 12:14 PM.
                              CNC machines only go through the motions

                              Comment


                              • #45
                                so its like with the dogs?

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