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Need to remove 5MT arbor from Jacobs 20N SuperChuck

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  • Need to remove 5MT arbor from Jacobs 20N SuperChuck

    I bought a Jacobs 20N (3/8 to 1 inch capacity, a substantial drill chuck) SuperChuck at auction a while back. The chuck came with a 5MT arbor. I need to remove this arbor so that I can mount the chuck on a 4MT arbor. I am finding it difficult to remove the arbor - this arbor dia in the chuck (tapered) is approx 1.38 inch in diameter. The chuck has been drilled thru the center to the arbor. I have tried to support the back end of the chuck while using a large hammer and punch to drive the arbor off of the chuck. I have done this successfully with slightly smaller drill chucks but this one did not budge. I have tried to use my 30T hyd press to remove the chuck, also no success. I am aware that Jacobs sells tapered wedges for remove drill chucks from an arbor - I am trying to avoid buying the set of tapers for a one time use. I could try to heat up the chuck body and try the hammer and punch again - hoping that the heat does not spread rapidly into the arbor. I did not want to drag out the oxy-acetylene hoses out for a one time use. Any suggestions?
    Metro Detroit

  • #2
    If you can't get the arbor to pop using your 30-ton press it's doubtful that the wedges would do it.
    I would try putting a little heat to the body of the chuck, let it cool and try pressing again.
    You you may have to repeat the process a few times.
    the repeated cycles of expansion and contraction maybe enough to loosen it up.
    Worst worst case scenario, you may have to disassemble the entire chuck so you can heat the entire body up good.

    JL......

    Comment


    • #3
      If the arbour isn't hardened, and you don't need to save it for another use, then cut it off close to the back of the chuck, and put a big drill down the remains, but not quite full depth. That should ease the grip enough for you to be able to drift the stub out.
      'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

      Comment


      • #4
        Whach Out!! Gramatic affect.

        They tend to pop loose with some drama sometime. Mainly when they have been matted up for years.

        No wedge option? Are you sure? Most large onse I have seen might have a very thin wedging surfave. Xause otherwise. its a tap fest. And that works also.

        Check for a very thin slot inbetween the chuck and holder. Sometimes.

        I dont like hitting metal tools. LOL JR

        Comment


        • #5
          Are you sure that its not a threaded arbour?

          With the hole drilled through to the chuck it sounds as if someone has been there before!
          I have tools I don't know how to use!!

          Comment


          • #6
            Originally posted by ptjw7uk View Post
            Are you sure that its not a threaded arbour?

            With the hole drilled through to the chuck it sounds as if someone has been there before!
            Thats actually a very good point.

            Some arbors are threaded/ Very good point..

            I dont think this one is, its just old. Do what you are not supposed to do, side load. Lightly, I mean tap, tap tap around the matting point. It might pop loose.

            I dont think more tonnes are needed Jr

            Comment


            • #7
              The best thing for you to do is send the chuck to me. My lathe takes a MT5 and I need a bigger drill chuck for it. I might even be convinced to pay the postage.
              Location: The Black Forest in Germany

              How to become a millionaire: Start out with 10 million and take up machining as a hobby!

              Comment


              • #8
                Jacobs Super chucks are not made with threaded arbors as an option. JT taper size is marked right on the body of the chuck.
                How do you know how much force you applied, does your H frame press have a gauge?

                The press is the way to go for a large taper.
                Keep applying pressure until the arbor pops out, catch the arbor below in a box padded with carpet if you expect to reuse or sell it.
                Or send it to BF.

                Comment


                • #9
                  30 tons is a lot of force.
                  Without question in my mind,
                  that should be more than enough to pop the taper.
                  I would question your setup, and if all that force
                  is actually acting to separate the arbor and chuck.
                  Take offense to me questioning your setup if you want,
                  you aren't going to hurt my feelings. I just keep coming
                  back to the fact that I have pressed a lot of tapers loose.
                  And 30 tons seems like an awful lot. Make sure everything
                  is straight and perpendicular. If you are using one of those
                  cheap presses with a bottle jack, those are horrible because
                  they have the length of the jack as column stack and will
                  cause side load and potentially buckling. You may not be
                  getting 30 tons with a straight down force vector. Maybe
                  10 tons could be lost to side load friction. Is your pressure
                  gauge calibrated or at least comparatively accurate?
                  Are you properly calculating the size of the ram?
                  Lots of variables there. I venture to say that if you account
                  for enough of them, your chuck arbor will come out.


                  ---Doozer
                  DZER

                  Comment


                  • #10
                    Originally posted by Doozer View Post
                    30 tons is a lot of force.
                    Without question in my mind,
                    that should be more than enough to pop the taper.
                    I would question your setup, and if all that force
                    is actually acting to separate the arbor and chuck.
                    Take offense to me questioning your setup if you want,
                    you aren't going to hurt my feelings. I just keep coming
                    back to the fact that I have pressed a lot of tapers loose.
                    And 30 tons seems like an awful lot. Make sure everything
                    is straight and perpendicular. If you are using one of those
                    cheap presses with a bottle jack, those are horrible because
                    they have the length of the jack as column stack and will
                    cause side load and potentially buckling. You may not be
                    getting 30 tons with a straight down force vector. Maybe
                    10 tons could be lost to side load friction. Is your pressure
                    gauge calibrated or at least comparatively accurate?
                    Are you properly calculating the size of the ram?
                    Lots of variables there. I venture to say that if you account
                    for enough of them, your chuck arbor will come out.


                    ---Doozer
                    Like I said , if 30 tons doesn't move it, wedges won't.

                    JL.............

                    Comment


                    • #11
                      As stated before, set it up in your press, put pressure on it, apply heat to chuck body, maybe even spray the arbor with freeze off or computer duster and Tap it with a hammer
                      when it comes off it will do so rapidly and loudly

                      Comment


                      • #12
                        - for us sitting here, we don't know for sure that the 30T was put toward separating chuck and arbor.
                        - if jacobs, the chuck model will clearly define what's there, i.e. jacobs taper etc. if its a 20N, its 5jt taper
                        - dollars to donuts the arbor is hardened. I tried once, about impossible to find one that wasn't. Home made might not be, but in that size range i doubt it has a home made arbor
                        - The wedges work, almost always. (in fairness, I have chucks that size but can't remember if I've ever needed to remove one)
                        - if you don't want to buy them, make some. They won't fair that well not being hardened but might work. Or buy them, they're not much money compared to the cost of screwing up a 1" ball bearing chuck or the time to make them for that matter. Early on I bought all the sizes, no regrets given a challenging job is dealt with in minutes.
                        - I had one once that was a bear, only time wedges didn't work. I held the arbor in a vise and tightly as I could and worked away with hundreds of blows with copper bar and hammer. arbor kept working out of the vise but eventually it came of. Sometimes the number blows is the trick, not how massive they are. Despite copper being softer, you will risk damaging the body. I didn't care and planned to scrap the chuck and eventually it did work
                        Last edited by Mcgyver; 09-23-2021, 09:44 AM.
                        in Toronto Ontario - where are you?

                        Comment


                        • #13
                          If possible tap the hole and and put a Allen head bolt in and thigh en as hard as you can. Heat the chuck, then dip the arbor in ice water. You may have to drill the hole larger to get a large enough bolt. Some times hitting the end of the arbor will jar it lose, It can take a lot of messing with but it should come a part. Relay tighten the bolt, use a pipe on the a Allen wrench, this puts pressure on it while you are working on it. We used to tap new chucks just in case.

                          Jon
                          SW Mi

                          Comment


                          • #14
                            I would put it back in the press, crank down on it, and apply heat to the chuck body.
                            The most stubborn 16N chucks I ever had required a sledge to remove.
                            25 miles north of Buffalo NY, USA

                            Comment


                            • #15
                              Had the same issue with a 20 N, large chuck so there is a lot of surface (gripping) area. I drilled the chuck for a 3/8 cap screw, and … drilled a cross hole in the arbor (they are not hardened) for a pin for the wedges to bear against, and made a couple of wedges. Put PB blaster in it for a couple of days, then used a bench vise for the wedges and tightened the 3/8 cap screw while heating the lower portion of the chuck body. It took some work, but I got it out.
                              Mike Hunter

                              www.mikehunterrestorations.com

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