Announcement

Collapse
No announcement yet.

Grind jacobs 14N chuck jaws?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by Bented View Post
    This would be an excellent use of Penurioustic Machining.
    Seriously?

    Comment


    • #17
      Originally posted by challenger View Post

      Seriously?
      Of course (-:

      penurious

      ADJECTIVE
      • 1 formal Extremely poor; poverty-stricken.
        ‘a penurious old tramp’
        More example sentences
        Synonyms
        1. 1.1 Characterized by poverty.‘penurious years’
      • 2 formal Unwilling to spend money; mean.
        ‘a tight-fisted, penurious boss whose wage scale is well below other bandleaders’

      Comment


      • #18
        I have just bought a NOS Jacobs No.34 0-1/2" and have drilled the body to remove the MT3 arbor for replacement with a MT2 one. The chuck is one of the British made ones, not the current type. I have been trying the jaws with a length of 8mm diameter centreless ground carbide, and if I have it just holding with the front of the bar level with the front of the jaws, I can rock it about a little. The jaws touch at the front first. There is probably about 0.005" slope on the jaws, which disappears as the jaws are tightened. As the British ones were made to the same quality standards as the USA manufactured ones, I assume the slope in the jaws is intentional, there would be no way to be sure it that is correct if the chuck had been used.

        Comment


        • #19
          2 formal Unwilling to spend money;
          Or maybe some of us just have a thing about fixing things rather than throwing them out, no matter how impractical the repair might be...
          "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

          Comment


          • #20
            Originally posted by old mart View Post
            I have just bought a NOS Jacobs No.34 0-1/2" and have drilled the body to remove the MT3 arbor for replacement with a MT2 one. The chuck is one of the British made ones, not the current type. I have been trying the jaws with a length of 8mm diameter centreless ground carbide, and if I have it just holding with the front of the bar level with the front of the jaws, I can rock it about a little. The jaws touch at the front first. There is probably about 0.005" slope on the jaws, which disappears as the jaws are tightened. As the British ones were made to the same quality standards as the USA manufactured ones, I assume the slope in the jaws is intentional, there would be no way to be sure it that is correct if the chuck had been used.
            The slope you speak of may also be how the body is ground and not the jaws.

            Comment


            • #21
              If I can find the piece of tube for taking this type of chuck apart when I get back to the museum, I will take the chuck apart to clean and regrease it. I will then be able to measure the angle of the gripping edge of the jaws relative to the opposite side.

              Comment


              • #22
                Get yourself some of these-
                https://www.mcmaster.com/4522A123-8921A162

                Chuck the stone in the lathe chuck, put the Jacobs in the tail stock, open the Jacobs up, crank the tail stock out and slip it over the stone. Measure and see to it that the full grip length of the Jacobs jaws will be contacted by the stone. Start lathe up running 5-600 rpm, slowly close the Jacobs up until the stone lightly contacts the jaws, stroke the tail stock back and forth so the full length of the Jacobs jaws are covered. Rinse and repeat a couple times, then loosen off the Jacobs and slide the tail stock back. Check to see that the grip face of each jaw has been cleaned up over it's full length. If they have, flush it with mineral spirits and blow it out with compressed air, return to service.

                Be aware however that there are a lot of old Jacobs chucks floating around that were used in production since WWII. A lot of them were wornout, were thrown out and made it into the machine tool afterlife in garages and basements. Once the body is worn, the chuck is junk and there is no improving it.

                For new chucks have a look at LFA. Made in France and quite good, KBC sells them as well as several others-

                http://www.lfachucks.com/super-chucks.html
                I just need one more tool,just one!

                Comment


                • #23
                  Originally posted by old mart View Post
                  If I can find the piece of tube for taking this type of chuck apart when I get back to the museum, I will take the chuck apart to clean and regrease it. I will then be able to measure the angle of the gripping edge of the jaws relative to the opposite side.
                  I took s Jacobs chuck apart in front of an old machinist
                  using a copper hammer, and he could not believe his eyes.
                  He was dumbfounded that a few well placed hits with the
                  copper hammer was all it took. He told me he had never
                  seen someone take one apart, let alone so quick and easy.
                  It is just one of my engineer party tricks to try and make
                  friends with the machinists. The place I work now, I just
                  bought the machinists tee shirts with pictures of Bridgeports
                  on them. It is not buying friends, it is just getting off on the
                  right foot.

                  --Doozer
                  DZER

                  Comment

                  Working...
                  X