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  • Adapter for lathe center

    I am in need of an adapter for a lathe.The spindle is threaded and bored for a #5 Morse and I need to go down to a #2 Morse for a dead center. What I want to do is to put on a face plate and use a dog to turn between centers. The only adapters (sleeves) I can find in the catalogs are way too long. My other option I have is to make one, something I don't want to do because I'm not into heat treating. Can anyone guide me?

  • #2
    I will be interested to hear what the experienced members have to say but I would not bother heat treating anything.

    I have a few tapers for various things that I have not heat treated and the the dead centre you want to be soft, at least on the point, so that you can turn it for true centre everytime you use it.

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    • #3
      MT sleeves are available hardened and unhardened or with just the tang hardened. They can be cut down to the length desired. If making your own adaptor, there is no need for it to be hardened.
      Jim H.

      Comment


      • #4
        I agree with all the above, except Artful is being a bit alarmist. It's right that a dead centre for the spindle would normally be soft, but that's so you can true it when you need to. If you need to true it every time you use it, something's wrong.

        You might as well get practiced at turning your MT5 taper, as it's likely you'll need another special some time, and a simple dead centre is the right place to start.
        Richard

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        • #5
          While I turn between centers on occasion, I rarely use a dog plate or faceplate. I have a flanged spud with a 60* point I chuck in the three jaw and true in place. I use one of the jaws to drive the dog.

          As far as truing the center after installation, it is good practice as the main reason for turning between centers is to achieve maximum concentricity. Original equipment with lathes should be a hard center for use in the tailstock and a soft center for use in the spindle. In the past, the tailstock center was termed the dead center and the spindle center was the live center. This can lead to confusion when reading some of the older machining texts.
          Jim H.

          Comment


          • #6
            Originally posted by JCHannum
            This can lead to confusion when reading some of the older machining texts.
            Confusion indeed! This has always been a source of irritation to me.

            I first got the impression, based on reading wood turning lore, that it was live or dead, depending on whether it went 'round & round. So a solid center in the tailstock was dead, but a ball bearing center was live.

            Then when I developed an interest in metal machining and lathes it seemed the definitions were different, and the tailstock center is always "dead". To me if that tailstock center is turning (ball bearing), it should be called "live".

            Comment


            • #7
              this may give someone an idea. i wound up with 2 old mt3 tailstock rams in a junk box buy. one i cut down to 5" to enable use of mt3 tools in the chuck. the other i cut down and made a slotted face plate that i welded to it.

              Comment


              • #8
                I did this myself last year (for a Jarno external taper) and would suggest the following method -
                • In a suitable blank, bore (and ream) your MT2 taper
                • Putting that to one side, put a piece of material in the chuck and machine a male MT2 mandrel
                • Leaving the mandrel in the chuck, mount your blank on the mandrel
                • Turn the MT5 taper

                This should ensure that both tapers are concentric and give you somewhere to hold the adaptor while turning. I second the thought that heat treatment is probably not necessary. If you are still concerned you could make the adaptor from a harder steel 4140 or similar.
                A handy thing I then do is use the mandrel to mount a centre drill with a grub screw or similar in it - quicker than putting a chuck and drill in the tailstock.

                Michael

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                • #9
                  The Morse adapters that are supplied for the headstock by the lathe maker are stubby. They generally fit up flush or sticking out slightly from the spindle bore. A standard adapter will stick out to far and machining it shorter will not help because the ID taper will have to be opened up so the center sets in deeper.

                  You need to look for an adapter that is made for the headstock. You can check with some lathe companies and see if they have the adapter you need. It doesn't matter what lathe company as long as you can find a #5 to #2 adapter for the headstock.
                  It's only ink and paper

                  Comment


                  • #10
                    Why not use a driving center instead of a lathe dog, as that allows working on length finished pieces and keeps the whole surface free for working.
                    Amount of experience is in direct proportion to the value of broken equipment.

                    Comment


                    • #11
                      Originally posted by lynnl
                      C
                      I first got the impression, based on reading wood turning lore, that it was live or dead, depending on whether it went 'round & round. So a solid center in the tailstock was dead, but a ball bearing center was live.

                      Then when I developed an interest in metal machining and lathes it seemed the definitions were different, and the tailstock center is always "dead". To me if that tailstock center is turning (ball bearing), it should be called "live".
                      If you have a ball bearing center in the tail stock, then it is live by the definition that it turns with the work rather than rubbing against the work (and is typically sold as "live"). So, you have two live centers, one with ball bearings in the tail stock and one in the headstock which does not have ball bearings (and thus was probably purchased as "dead") but uses the headstock bearings. But technically, only part of a ball bearing center goes round and round, not the whole thing. So the devices sold as "live centers" in tool catalogs are all ball bearing (dead) centers and the ones sold as dead are live when you insert them in your headstock.

                      As far as friction, heat, wear, and lubrication are concerned, the ball bearing center, and any type of center inserted in the headstock, might as well be live in that it revolves with the work piece rather than rubbing against it. As far as motive force is concerned, only the one piece center inserted in the headstock or in an actively driven tailstock would be live. As far as whether the center is inserted into a rotating or stationary taper is concerned, the headstock center is always live (unless there is no driven headstock, such as in certain grinders) and the tailstock center is always dead (unless you have a power driven tailstock). And by some definitions it is live if it is in the headstock end and dead if it is at the tailstock end.

                      We have 4 degrees of liveness/deadness in application:
                      Fully live: inserted in a driven spindle. driven rotating tip, driven rotating shank. Provides some motive force to the work though rarely the primary source of motive force.
                      Half live: inserted in a non-driven spindle or a rotating spindle but doesn't transmit the motive force of the spindle. non-driven rotating tip, possibly non-driven rotating shank. Rotates with the work so it doesn't rub, but provides no motive force.
                      Half dead: rotating tip, non-rotating shank. Rotates with the work so it doesn't rub but provides no motive force. Slight drag from bearings.
                      fully dead: non rotating tip, non rotating shank. Not only provides no motive force, it rubs against the work and provides significant drag, heat, and were.
                      The simple one-piece center is fully live in most headstocks and fully dead in most tailstocks and the ball bearing center is half dead in the tailstock and effectively half live in the headstock (even though the shank is driven).
                      The combinations boil down to three fundamental behaviors:
                      - Center provides (partial) driving force to the work (normally used in conjunction with a lathe dog). non-ball-bearing center in driven headstock.
                      - Center provides neither (partial) driving force nor substantial drag to the work. Ball bearing center in either headstock or tailstock, or any type in a non-driven rotating headstock or tailstock spindle.
                      - Center resists the driving force of the spindle. non-ball-bearing center in non-rotating tailstock.
                      As far as the parts themselves are concerned, there is no live or dead until you put it in a machine and turn the machine on, there is just the ball-bearing center and the non-ball-bearing center.


                      Colvin, Fred and Frank Stanley, American Machinists' Handbook and Dictionary of Shop Terms, 3rd. Ed, 1956:

                      Center, Dead - The back center or the stationary center on which the work revolves. On many grinding machines both centers are dead.

                      Center, Live - The center in the revolving spindle of a lathe or similar machine. It is highly important that this should run true or it will cause the work to move in an eccentric path.
                      These are the same definitions as used in the 1908 edition. So, the definition of "live center" was apparently the same for 48 years across 9 editions of two books.

                      Colvin, Fred; Machinist's Dictionary, 1956:
                      CENTER, LIVE - The center in the revolving spindle of a lathe or other machine. It is important that all live centers run true to avoid rotating the work in an eccentric path.

                      CENTER, DEAD - In lathe or similar machine work, the center which does not revolve with the work. In mechanisms involving a crank and a connecting rod ...

                      CENTER, BALL BEARING-A center for lathe and similar work in which the dead, or tailstock, center contains a ball bearing. Instead of the work revolving on the sharp pointed center the center revolves with the work.
                      So, technically, (by 1956 definitions) the ball bearing center in the tailstock is apparently dead. It would be live if you had a rotating spindle in the tailstock, particularly a motor driven one synchronized with the headstock.

                      Wikipedia's definitions are more in line with what you see in catalogs today (but not consistent with traditional use), with the ball bearing center considered live and the solid center considered dead no matter which end of the lathe it is installed in:
                      http://en.wikipedia.org/wiki/Lathe_center
                      A dead center (one that does not turn freely, i.e., dead) may be used to support the workpiece at either the fixed or rotating end of the machine. When used in the fixed position, a dead center produces friction between the workpiece and center, due to the rotation of the workpiece. Lubrication is therefore required between the center and workpiece to prevent friction welding from occurring. Additionally the tip of the center may have an insert of carbide which will reduce the friction slightly and allow for faster speeds. Dead centers may also be fully hardened to prevent damage to the important mating surfaces taper of the taper and to preserve the 60° nose taper.

                      A live center or revolving center is constructed so that the 60° center runs in its own bearings and is used at the non driven or tailstock end of a machine.[2] It allows higher turning speeds without the need for separate lubrication, and also greater clamping pressures. CNC lathes use this type of center almost exclusively and they may be used for general machining operations as well. Spring loaded live centers are designed to compensate for center variations, without damage to the work piece or center tip. This assures the operator of uniform constant tension while machining. Some live centers also have interchangeable shafts. This is valuable when situations require a design other than a 60° male tip.
                      Dictionary.com/Random House Unabridged 2011:
                      a tapered rod, mounted in the headstock spindle (live center) or the tailstock spindle (dead center) of a lathe, upon which the work to be turned is placed.
                      Tool catalog use is based on construction, not application.

                      Still confused? Join the club. :-) Machine Shop lexicography has been more or less dead for about 55 years. Fred Herbert Colvin died in 1965 and Machinists' Dictionary was his last, of about 75 books (including new editions, about 45 1st editions) between 1895 and 1956 plus he was editor of both competing major machining publications of his time. He 70 and retired before world war II but was pulled out of retirement to aid the war production and still wrote new books/editions. His biography "60 years of men and machines" is a good read. Who else has the chops to be the Noah Webster of machining? His last dictionary was 496 pages. He started as an apprentice in a machine shop on July 5, 1883.

                      Comment


                      • #12
                        whitis

                        What a wonderful explanation, you've absolutely nailed it.

                        But with an analytical mind such as yours, having a meal must be a real bummer - all those permutations


                        john
                        John

                        I used to be indecisive. Now I'm not so sure , but I'm not a complete idiot - some bits are still missing

                        Comment


                        • #13
                          I agree with JCHannum

                          1) Turn a piece of CRS to a shoulder and cut it off.

                          2) Put the piece in a three jaw chuck holding on the turned diameter with the shoulder against the front of the chuck jaws.

                          3) Turn a 60 degree angle on the front of the piece.

                          The turned angular section is now running dead true to the spindle of the lathe within the limits of the lathe's accuracy.

                          4) Mount your part centered on this angle with a lathe dog attached making sure the tail of the lathe dog hits the side of the closest jaw of the 3 jaw.

                          5) You are ready to work on your project.

                          The next time you want to turn between centers put the same piece back in the 3 jaw and simply turn a new surface on the 60 degree angle to re-true it.,

                          Comment


                          • #14
                            Originally posted by JCHannum
                            While I turn between centers on occasion, I rarely use a dog plate or faceplate. I have a flanged spud with a 60* point I chuck in the three jaw and true in place. I use one of the jaws to drive the dog.

                            As far as truing the center after installation, it is good practice as the main reason for turning between centers is to achieve maximum concentricity. Original equipment with lathes should be a hard center for use in the tailstock and a soft center for use in the spindle. In the past, the tailstock center was termed the dead center and the spindle center was the live center. This can lead to confusion when reading some of the older machining texts.
                            what Jim said. spud in the three jaw is quicker and always dead on because you skim it. Live centre is the one in the headstock, dead in the tailstock, and the ones with bearings are rotating centres not live centres....but the correct use of these terms has been almost so completely abandon that its a bit swimming upstream worrying about it - I confess to occausionaly, when tired, sloppily referring to the rotating centre as live; a serious machine shop lexicon faux pas!

                            Artful, hardening the adapter would only serve the purpose of preventing dings and warts caused by ham fisted students or employees knocking them about, not an issue for a careful man in his own shop. If anything, you could argue it would be better to have it soft - the presence of a chip might then do more damage to the adapter than spindle taper, not sure how worked up I'd get about that argument, but I see no reason to worry about hardening them for you own use.
                            Last edited by Mcgyver; 06-10-2011, 08:06 AM.
                            .

                            Comment


                            • #15
                              [QUOTE=Mr Ron]I am in need of an adapter for a lathe.The spindle is threaded and bored for a #5 Morse and I need to go down to a #2 Morse for a dead center. What I want to do is to put on a face plate and use a dog to turn between centers. The only adapters (sleeves) I can find in the catalogs are way too long. My other option I have is to make one, something I don't want to do because I'm not into heat treating. Can anyone guide me?[/QUOTE]
                              Be careful, some lathe manufacturerers use odd sizes. I had a very old Colchester which I thought was 5MT but it turned out was bored 4 1/2MT, so I had to make an adaptor. As others have said, whats the need for hardening, theres no moving parts involved and its not as if you'll be fitting and removing this on a daily basis for years and years. If you make the adapter OD first, and then put in in the spindle to bore the 2MT, make a mark on the adapter and on the end of the spindle nose so that you can put it back in the same place each time. Then there should be no question about it running true. I know that traditionally the spindle centre was left soft, but 2 reasons, one so that you could true it up, two there was no need to harden it
                              because nothing rotated on it. To be honest I haven't found the need to true one up for many years, and I don't even think I have a soft centre, they are all HSS.

                              Richard

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