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  • Jacobs Chuck Delimna

    I have a Jacobs 3B chuck with 45/68-16 THD thread mount and has the same stamped on it.

    t's a 5/8" capacity chuck.

    Jacobs only lists a 3B as having 5/8-16 thead mount.

    What the heck do I have here? I can't find any reference to an arbor I can use or what this chuck was for.

    I called Jacobs but both tech guys are out untl Monday.

    Any words of wisdom?
    I'm in it for the parking....

  • #2
    Originally posted by kcleere
    I have a Jacobs 3B chuck with 45/68-16 THD thread mount and has the same stamped on it.

    t's a 5/8" capacity chuck.

    Jacobs only lists a 3B as having 5/8-16 thead mount.

    What the heck do I have here? I can't find any reference to an arbor I can use or what this chuck was for.

    I called Jacobs but both tech guys are out untl Monday.

    Any words of wisdom?
    I've got at least a word of curiosity. How! How did you determine that you had a 45/68-16 thread? Are you saying it has "45/68" stamped on the chuck body?
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

    Comment


    • #3
      Originally posted by TGTool
      I've got at least a word of curiosity. How! How did you determine that you had a 45/68-16 thread? Are you saying it has "45/68" stamped on the chuck body?
      Yes as stated in my opening line.....
      I'm in it for the parking....

      Comment


      • #4
        Can You verify that it is 16 tpi?
        Can You measure the bore with a inside caliper or hole guage etc. ?
        I was going to ask if You were just yanking our chains, but I am curious as to what You have.

        Steve

        Comment


        • #5
          LOL...nah...not jerking chains. I went ahead and took a pic. The pic makes it look like 45/84 but that 8 is really a 6 and when I measure the bore I get the 45/64th. As far as the threads go yes I can poke a thread gauge down there lather tonight and check it but I have no reason to think oherwise due to the markings on the chuck. It's a nice smooth chuck that does not look used at all but considering the thread size I think we know why.

          I'm in it for the parking....

          Comment


          • #6
            It should be 45/64 not 45/68. It is a Jacobs option on some of the 3B & 3xB series chucks. So what's the problem?

            Comment


            • #7
              That's a 45/64-16. Someone stamped over the 6.

              Comment


              • #8
                Originally posted by CCWKen
                It should be 45/64 not 45/68. It is a Jacobs option on some of the 3B & 3xB series chucks. So what's the problem?
                Problem is I'd like to use it eiher with an MT2 or 1/2" straight shank and I can't find any arbors to fit much less any reference to that thread size.

                And yea fatfingered the 68 in the original.
                I'm in it for the parking....

                Comment


                • #9
                  45/64" is 1/64" over 11/16" and IF the bore measures 45/64, as you say it does, which is .703 then you may have a 3/4"-16 thread. That's because the 3/4"-16 thread uses an 11/16" drill to thread the hole.

                  Have you tried a 3/4"-16 bolt in the hole?
                  It's only ink and paper

                  Comment


                  • #10
                    Originally posted by Carld
                    45/64" is 1/64" over 11/16" and IF the bore measures 45/64, as you say it does, which is .703 then you may have a 3/4"-16 thread. That's because the 3/4"-16 thread uses an 11/16" drill to thread the hole.

                    Have you tried a 3/4"-16 bolt in the hole?
                    You could be right...and that's worth a try.
                    Thanks
                    I'm in it for the parking....

                    Comment


                    • #11
                      Problem is I'd like to use it eiher with an MT2 or 1/2" straight shank
                      Why can't you make a special 45/64-16 threaded straight shank on your lathe?
                      Problem solved.

                      Comment


                      • #12
                        It is easy to make a shaft to put it on, 1/2 or any size. The thread fit should not be snug The most important thing is to have it fit against a shoulder, then it will be true. I recomend you single point the threads and cut the shoulder it rests against.
                        scariest thing to hear " I am from the government and i am here to help"

                        Comment


                        • #13
                          Chuck

                          I expect the chuck was made for an OEM product by Jacobs.

                          JRW

                          Comment


                          • #14
                            It could well have been made for a special machine. As in, "You need a new chuck? Sure, we have the specials and they list for a thousand bucks".

                            I recently bought some tooling with a 5/8-23 thread on the shank. I called the manufacturer to verify what I was seeing, they grudgingly admitted it was so they would be the only source for replacement parts. Unless you have a CNC lathe, that is....


                            A simple solution here is to get a blank #2 or #3 Morse arbor and thread it accordingly.

                            Comment


                            • #15
                              The 3B only comes in 5/8-16 and 45/64-16--No 3/4-16. You can get a 36B in 3/4-16. These chucks are still sold. The 3B, 45/64-16 is about $200 new.

                              My next question is: Why did you buy it?

                              As DR says, just cut a MT-to-JT arbor down and thread it. What size is your Morse Taper? The JT side will probably need to be a 4JT. I've only seen this size with an MT3 shank though. If you need MT2, you may have to make your own.

                              Comment

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