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A question about live centers

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  • A question about live centers

    Over the years I have purchased and used many live centers,I have never seen one that will eject from the tailstock.I allways have had to make a screw on projection or if there wasnt a tapped hole in the end I have tig welded somthing on so that it would eject. I was wondering what other have done or am I missing something.

  • #2
    My simple remedy for that problem...a plastic fallers wedge with a slot cut in it. One light pop with a hammer and out comes the center.

    Ernie (VE7ERN)

    May the wind be always at your back

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    • #3
      my live center ejects at about 0.5" remaining of the tailstock.. *shrugs*
      the drill chuck.. INCLUDED with my lathe, on the otherhand, had to have the tang ground down to even FIT into the tailstock properly, And ejected at like 1".. So I choped it down to eject at exactly 0
      Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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      • #4
        Dockrat, I think it's your lathe.

        Both my south bends will kick out a center right at the '0' mark on the ram. They eject a typical #2 morse taper drill chuck at about the 1/4" mark. I've noticed that some suppliers, (Little Machine Shop for one) offer a 'short' #2 morse taper for use in lathes, and I think that is what your live centers have (no tang).

        It's my understanding that the tang on a morse taper is merely a driving surface for ejecting the tool, not an anti-rotation device. (That's the job of the taper.) So, on your tailstock, which does not allow access for a wedge, there is no need for the tang or the extra length.

        I do have a couple tools that don't eject as soon as I'd like. One had a tapped hole on the end already, and I tapped the other. A couple of 10-24 round head screws and some little brass spacers and now everything ejects just beyond the '0' mark.

        Edit to add: You only see it on the centers because they come with the 'short' taper, most likely because they are a 'lathe only' tool, unlike a drill chuck. Am I making sense?
        Last edited by fciron; 02-28-2011, 09:02 PM.

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        • #5
          I have seen the same problem. Twice I have had to make a brass insert to press in the end of a live center to make it long enough to use the quill screw to force the taper out of the quill.

          Not all manufacturers make the taper long enough for some reason, cutting corners is my guess. I have slid a slug of brass in the quill and then socked the taper in so I could pop the taper out when I was done.
          It's only ink and paper

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          • #6
            Interesting point - I thought it was just me getting annoyed by this!

            Same problem - I had to put a short brass button in the end of my live centre to get it to autoeject.

            I have a dead centre (5 morse) that actually has an external thread just behind the point, and a knurled collar with holes for a C spanner. Seems a had way of doing a simple job, but it will eject from a socket that doesn't have any other means of ejecting.

            I still don't know if tangs on drills were designed to drive or not - if not, then why don't centres also have tangs?

            Ian
            All of the gear, no idea...

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            • #7
              I don't think centers need tangs since centers don't impart rotational force.
              When turning between centers it is the dog+drive plate that does all the driving.

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              • #8
                now im happy

                I thought I was the only one. I like the plastic wedge, but wont work with
                all my dead centers that i made. I never gave that a thought when I made
                them being just a little too short so I glue buttons on them no need for
                overkill they now come right out.

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                • #9
                  Over and over this comes up. The tang IS NOT for driving the tool. It is for ejection only. If your taper doesn't hold the tang will twist right off. If the tapers are in good condition, properly machined and clean, they are the next best thing to a weld, except that you can pop it out when needed.
                  Dockrat has the right idea.

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                  • #10
                    My centers seem to eject OK from the Logan, but I have drill chucks that I had to cut the tang on to eject with a sensible amount of remaining travel (like under 0.5 inch).

                    I don't plan to use those chucks in the drill presses, so the short tang is no problem, no need for ejection from a DP spindle.

                    "tdm" is correct, although there are eternal optimists....... if the drill's taper looks like a corn cob, as it generally does in "Bubba's" shop, the tang is likely the only thing driving the drill..... and it is going to break off pretty soon, if it has not already. That doesn't make it right.
                    1601

                    Keep eye on ball.
                    Hashim Khan

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                    • #11
                      Originally posted by Ian B
                      I still don't know if tangs on drills were designed to drive or not - if not, then why don't centres also have tangs?
                      Centers don't have tangs because they are not ejected by hammering on a wedge. They're pushed out by retracting the tailstock, nice, easy and controlled.

                      The tang is a relieved end so that any burrs or dents incurred by hammering do not lock your taper into your drill press quill. (I once had to cut the end of a tang off with a little cape chisel to save an old drill press. )

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                      • #12
                        It's true the live center tapers don't have a tang and are sometimes to short because they don't have the tang. The taper is usually hollow and it's easy to press or screw a plug into it to extend it so the tailstock quill screw can eject the live center out of the quill.

                        It's not a big issue, just make an extension or slide a slug of brass into the quill taper before you insert the live center.

                        You can use a wedge if you want to, it's just a matter of preference.

                        As they say, what ever blows your dress up will work.
                        It's only ink and paper

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                        • #13
                          Not a "solution" but an additional question/point.

                          Does the lack of ejection have to do with the screw in the tailstock?

                          I have noticed on the one I am replacing, the length past the end of the threaded section (Acme; the portion that would be in the ram nearest where the end of the center would be) is quite short and judging from wear, would have been maybe a 1/4" longer at one point in its history.

                          Rather than threading or inserting a screw into the center, could one "cap" the end of the tailstock screw, making it that bit longer?

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                          • #14
                            Originally posted by Carld
                            As they say, what ever blows your dress up will work.
                            If it works, it's right.

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                            • #15
                              I guess I made another new-bee mistake. I made a steel button instead of the proper brass one like the rest of you.

                              Oh, woe is me!
                              Paul A.

                              Make it fit.
                              You can't win and there is a penalty for trying!

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