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Lathe chucks leave marks on work ?

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  • Lathe chucks leave marks on work ?

    After 3 years of collecting accessories and refurbishing, I'm starting to use my old South Bend heavy 10 lathe. I have a 3 jaw chuck, a 4 jaw chuck, and a set of 5C collets. It's fairly obvious that the jaws on both chucks will leave marks on any shaft I chuck up . The 3 jaw chuck has an aggressive toothed pattern on the jaws. What's the best procedure for avoiding leaving jaw marks if I'm turning something that won't be parted off ? I can see wrapping the shaft with thin brass or aluminum shim stock, or attaching pieces of shim stock directly to the jaws using spray on glue or thin double sided tape. But those are only guesses, since I've never tried either. Any suggestions ?

  • #2
    jaws

    Learn to bore soft jaws to shaft size.
    Jim

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    • #3
      Yes you have right idea. You can also get thick (like 4 gauge) copper wire and put a ring of it around the end in the chuck. Especially good if you have a center in the other end.

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      • #4
        For anything not demanding on the runout, I use pieces of cardboard. Usually from soda boxes.

        If it need to be close, break out the scissors and a beer can. Cut strips of that.

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        • #5
          I prefer to use copper or lead shims instead of aluminum or brass as the copper & lead are softer.

          2X on boring soft jaws, but keep in mind a lot of work can be done in a three jaw and any marks will not be an issue.

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          • #6
            Thanks for the ideas. I think they all will work in different situations. ( The beer can strips certainly has special appeal.) A material that sticks magnetically to the chuck jaws might be convenient. If there was one material that might cover all the bases, perhaps it would be thin shim stock made of magnetized dead soft steel, covered on one side with copper. Maybe there's an idea for a new product ? Refrigerator magnet material is probably too soft, and might not compress evenly.

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            • #7
              I always used to use a thicker paper, but last summer my 6 year old was in my shop while I was doing something and she left a few playing cards there. A couple months ago I was searching for some paper and I came across the joker from my daughter's deck. I used it and it worked great, I got a deck of cards from the house and now I keep them in the shop just for that.

              I should say I also use the beer/pop cans when I think Aluminum would be better.

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              • #8
                I buy sheets of 5 mil brass from the hobby shop and use that, cut to appropriate size. I usually get 5 to 8 uses on 3/8 bolts when clamping to the threaded end. Soda can material is 3 mil aluminum and beer cans are 4 mil domestic (US) and ~5 mil imported.

                Pops

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                • #9
                  When a machinist says "mil" it's millionth of an inch. Catch up here.

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                  • #10
                    Yup. Pad the jaws. Annealed copper works best for brass, bronze, and steel. Stout cardboard and gasket material works well also. Send me your eMail addy and I'll send you Word.doc files with photos of two articles I wrote for HSM; one on the three jaw chuck, one on the four jaw.

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                    • #11
                      Originally posted by tdmidget
                      When a machinist says "mil" it's millionth of an inch. Catch up here.
                      Machinery's Handbook - page 2403 - 1 mil = 0.001 inch

                      Dad's cousin, master machinist for NASA projects - 1 mil = 0.001 inch

                      Dictionary - online "1. A unit of length equal to one thousandth (10-3) of an inch (0.0254 millimeter), used, for example, to specify the diameter of wire or the thickness of materials sold in sheets."

                      Webster's - "Definition of MIL
                      1: thousand <found a salinity of 38.4 per mil>
                      2: a monetary unit formerly used in Cyprus equal to 1⁄1000 pound
                      3: a unit of length equal to 1⁄1000 inch used especially in measuring thickness (as of plastic films)

                      Common usage by the machinists teaching at our high school, community college and at several of the professional shops I pester regularly: 1 mil = 0.001 inch.

                      I'll stick with what I know, thank you.

                      Pops

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                      • #12
                        Originally posted by tdmidget
                        When a machinist says "mil" it's millionth of an inch. Catch up here.
                        You must learn to interpret things in their proper context.
                        Lynn (Huntsville, AL)

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                        • #13
                          My old business cards from my former employer are too stiff & scratchy for toilet paper, but just right to use in the milling machine vise and as pads on the three and four jaw chucks in the lathe.

                          David
                          David Kaiser
                          “You can have peace. Or you can have freedom. Don't ever count on having both at once.”
                          ― Robert A. Heinlein

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                          • #14
                            Originally posted by armedandsafe
                            Machinery's Handbook - page 2403 - 1 mil = 0.001 inch

                            Dad's cousin, master machinist for NASA projects - 1 mil = 0.001 inch

                            Dictionary - online "1. A unit of length equal to one thousandth (10-3) of an inch (0.0254 millimeter), used, for example, to specify the diameter of wire or the thickness of materials sold in sheets."

                            Webster's - "Definition of MIL
                            1: thousand <found a salinity of 38.4 per mil>
                            2: a monetary unit formerly used in Cyprus equal to 1⁄1000 pound
                            3: a unit of length equal to 1⁄1000 inch used especially in measuring thickness (as of plastic films)

                            Common usage by the machinists teaching at our high school, community college and at several of the professional shops I pester regularly: 1 mil = 0.001 inch.

                            I'll stick with what I know, thank you.

                            Pops
                            We disagree.
                            Last edited by tdmidget; 12-24-2011, 09:49 PM.

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                            • #15
                              Be nice, guys. Santa is watching .

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