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RE: [7x10minilathe] Chuck Grinding

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  • Old Boats
    It actually seems to have made the Craftsman worse, unless 0.013 or 0.020 are typos.. How did you actually do the grind? Did you use a fine wheel on the
    Message 1 of 6 , May 1, 2013
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      It actually seems to have made the Craftsman worse, unless 0.013" or 0.020" are typos..

      How did you actually do the grind? Did you use a fine wheel on the toolpost, open the chuck to about 1" and skim the chuck jaws?


      To: 7x10minilathe@yahoogroups.com
      From: buffumjr18@...
      Date: Wed, 1 May 2013 01:06:23 +0000
      Subject: [7x10minilathe] Chuck Grinding

       
      I have seen this mentioned in Home Shop Machinist, Machinists Worksghop, and some Lindsay books. Well, I had built a tool post grinder last year, so I thot I'd give it a try.

      Before I did, here are the runouts.

      Craftsman 3 jaw chuck
      .0033 at the chuck
      .013 at 9"

      Chinese "Semi-Steel" 6" 4 jaw
      N/A at the chuck. You "dial in" a 4 jaw.
      .038" at 9"

      After

      Craftsman
      .0015 at the jaws
      .020" at 9"

      Chinese 4 jaw
      .015 at 9"

      On all 4 9" measurements, I loosened the jaws, and rotated the round rod 90°, then retightened. In the case of the 4 jaw, redialed in. The defelection did not follow the side of the rod.

      I didn't use a forcing ring. I set the lathe to rotate as fast as it would go. The centrifugal force nearly duplicated the distortion of a load.

      By golly, it worked just like they said it would. I'm not getting collet-like accuracy, but it isn't as annoyingly off as it was.


    • bigmanfun
      What diameter opening did you use for the grinding? What size stone did you decide to use? Did you disassemble either of them after and clean them? How much
      Message 2 of 6 , May 1, 2013
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        What diameter opening did you use for the grinding?

        What size stone did you decide to use?

        Did you disassemble either of them after and clean them?

        How much metal, approximately, do you think you removed?

        Any other things you learned?

        Thanks,
        Thomas

        --- In 7x10minilathe@yahoogroups.com, "buffumjr18" <buffumjr18@...> wrote:
        >
        > I have seen this mentioned in Home Shop Machinist, Machinists Worksghop, and some Lindsay books. Well, I had built a tool post grinder last year, so I thot I'd give it a try.
        >
        > Before I did, here are the runouts.
        >
        > Craftsman 3 jaw chuck
        > .0033 at the chuck
        > .013 at 9"
        >
        > Chinese "Semi-Steel" 6" 4 jaw
        > N/A at the chuck. You "dial in" a 4 jaw.
        > .038" at 9"
        >
        > After
        >
        > Craftsman
        > .0015 at the jaws
        > .020" at 9"
        >
        > Chinese 4 jaw
        > .015 at 9"
        >
        > On all 4 9" measurements, I loosened the jaws, and rotated the round rod 90°, then retightened. In the case of the 4 jaw, redialed in. The defelection did not follow the side of the rod.
        >
        > I didn't use a forcing ring. I set the lathe to rotate as fast as it would go. The centrifugal force nearly duplicated the distortion of a load.
        >
        > By golly, it worked just like they said it would. I'm not getting collet-like accuracy, but it isn't as annoyingly off as it was.
        >
      • buffumjr18
        The new runout is actually just over .001. The runout at 9 was a little over .002 . The pre-grind runout was over two hundredths. About .0015 for an OLD
        Message 3 of 6 , May 2, 2013
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          The new runout is actually just over .001. The runout at 9" was a little over .002". The pre-grind runout was over two hundredths. About .0015 for an OLD (1950's) 3 jaw chuck is not too bad. Without CNC equipment to regrind it, there's nothing you can do about the irregular wear on the spiral.

          I used a ball wheel. The toolpost grinder appeared in Home Shop Machinist over a year ago. Two spindles. A collet for 1/4" glued on stones, and a spindle for wheels. The largest you can open the three wheels and still grind their full length is a little over an inch.

          The only downside to ANY grinding is you have to disassemble and detail clean your lathe after. The grinding dust gets EVERYWHERE, even in the apron gears. Clean with mineral spirits, and wash with dishwashing soap after. Yeah, I spoil my lathe, but it deserves it. Otherwise, the dust grinds patiently for years.

          --- In 7x10minilathe@yahoogroups.com, Old Boats <eezebilt@...> wrote:
          >
          > It actually seems to have made the Craftsman worse, unless 0.013" or 0.020" are typos..
          >
          > How did you actually do the grind? Did you use a fine wheel on the toolpost, open the chuck to about 1" and skim the chuck jaws?
          >
          > To: 7x10minilathe@yahoogroups.com
          > From: buffumjr18@...
          > Date: Wed, 1 May 2013 01:06:23 +0000
          > Subject: [7x10minilathe] Chuck Grinding
          >
          >
          >
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          >
          >
          > I have seen this mentioned in Home Shop Machinist, Machinists Worksghop, and some Lindsay books. Well, I had built a tool post grinder last year, so I thot I'd give it a try.
          >
          >
          >
          > Before I did, here are the runouts.
          >
          >
          >
          > Craftsman 3 jaw chuck
          >
          > .0033 at the chuck
          >
          > .013 at 9"
          >
          >
          >
          > Chinese "Semi-Steel" 6" 4 jaw
          >
          > N/A at the chuck. You "dial in" a 4 jaw.
          >
          > .038" at 9"
          >
          >
          >
          > After
          >
          >
          >
          > Craftsman
          >
          > .0015 at the jaws
          >
          > .020" at 9"
          >
          >
          >
          > Chinese 4 jaw
          >
          > .015 at 9"
          >
          >
          >
          > On all 4 9" measurements, I loosened the jaws, and rotated the round rod 90°, then retightened. In the case of the 4 jaw, redialed in. The defelection did not follow the side of the rod.
          >
          >
          >
          > I didn't use a forcing ring. I set the lathe to rotate as fast as it would go. The centrifugal force nearly duplicated the distortion of a load.
          >
          >
          >
          > By golly, it worked just like they said it would. I'm not getting collet-like accuracy, but it isn't as annoyingly off as it was.
          >
        • buffumjr18
          A typo. Not three wheels, three jaws. Disassembled the chuck before and after. Most of the grinding dust caught there.
          Message 4 of 6 , May 2, 2013
          • 0 Attachment
            A typo. Not three wheels, three jaws. Disassembled the chuck before and after. Most of the grinding dust caught there.

            --- In 7x10minilathe@yahoogroups.com, "buffumjr18" <buffumjr18@...> wrote:
            >
            > The new runout is actually just over .001. The runout at 9" was a little over .002". The pre-grind runout was over two hundredths. About .0015 for an OLD (1950's) 3 jaw chuck is not too bad. Without CNC equipment to regrind it, there's nothing you can do about the irregular wear on the spiral.
            >
            > I used a ball wheel. The toolpost grinder appeared in Home Shop Machinist over a year ago. Two spindles. A collet for 1/4" glued on stones, and a spindle for wheels. The largest you can open the three wheels and still grind their full length is a little over an inch.
            >
            > The only downside to ANY grinding is you have to disassemble and detail clean your lathe after. The grinding dust gets EVERYWHERE, even in the apron gears. Clean with mineral spirits, and wash with dishwashing soap after. Yeah, I spoil my lathe, but it deserves it. Otherwise, the dust grinds patiently for years.
            >
            > --- In 7x10minilathe@yahoogroups.com, Old Boats <eezebilt@> wrote:
            > >
            > > It actually seems to have made the Craftsman worse, unless 0.013" or 0.020" are typos..
            > >
            > > How did you actually do the grind? Did you use a fine wheel on the toolpost, open the chuck to about 1" and skim the chuck jaws?
            > >
            > > To: 7x10minilathe@yahoogroups.com
            > > From: buffumjr18@
            > > Date: Wed, 1 May 2013 01:06:23 +0000
            > > Subject: [7x10minilathe] Chuck Grinding
            > >
            > >
            > >
            > >
            > >
            > >
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            > >
            > >
            > >
            > > I have seen this mentioned in Home Shop Machinist, Machinists Worksghop, and some Lindsay books. Well, I had built a tool post grinder last year, so I thot I'd give it a try.
            > >
            > >
            > >
            > > Before I did, here are the runouts.
            > >
            > >
            > >
            > > Craftsman 3 jaw chuck
            > >
            > > .0033 at the chuck
            > >
            > > .013 at 9"
            > >
            > >
            > >
            > > Chinese "Semi-Steel" 6" 4 jaw
            > >
            > > N/A at the chuck. You "dial in" a 4 jaw.
            > >
            > > .038" at 9"
            > >
            > >
            > >
            > > After
            > >
            > >
            > >
            > > Craftsman
            > >
            > > .0015 at the jaws
            > >
            > > .020" at 9"
            > >
            > >
            > >
            > > Chinese 4 jaw
            > >
            > > .015 at 9"
            > >
            > >
            > >
            > > On all 4 9" measurements, I loosened the jaws, and rotated the round rod 90°, then retightened. In the case of the 4 jaw, redialed in. The defelection did not follow the side of the rod.
            > >
            > >
            > >
            > > I didn't use a forcing ring. I set the lathe to rotate as fast as it would go. The centrifugal force nearly duplicated the distortion of a load.
            > >
            > >
            > >
            > > By golly, it worked just like they said it would. I'm not getting collet-like accuracy, but it isn't as annoyingly off as it was.
            > >
            >
          • buffumjr18
            A typo. Not three wheels, three jaws. Disassembled the chuck before and after. Most of the grinding dust caught there.
            Message 5 of 6 , May 2, 2013
            • 0 Attachment
              A typo. Not three wheels, three jaws. Disassembled the chuck before and after. Most of the grinding dust caught there.

              --- In 7x10minilathe@yahoogroups.com, "buffumjr18" <buffumjr18@...> wrote:
              >
              > The new runout is actually just over .001. The runout at 9" was a little over .002". The pre-grind runout was over two hundredths. About .0015 for an OLD (1950's) 3 jaw chuck is not too bad. Without CNC equipment to regrind it, there's nothing you can do about the irregular wear on the spiral.
              >
              > I used a ball wheel. The toolpost grinder appeared in Home Shop Machinist over a year ago. Two spindles. A collet for 1/4" glued on stones, and a spindle for wheels. The largest you can open the three wheels and still grind their full length is a little over an inch.
              >
              > The only downside to ANY grinding is you have to disassemble and detail clean your lathe after. The grinding dust gets EVERYWHERE, even in the apron gears. Clean with mineral spirits, and wash with dishwashing soap after. Yeah, I spoil my lathe, but it deserves it. Otherwise, the dust grinds patiently for years.
              >
              > --- In 7x10minilathe@yahoogroups.com, Old Boats <eezebilt@> wrote:
              > >
              > > It actually seems to have made the Craftsman worse, unless 0.013" or 0.020" are typos..
              > >
              > > How did you actually do the grind? Did you use a fine wheel on the toolpost, open the chuck to about 1" and skim the chuck jaws?
              > >
              > > To: 7x10minilathe@yahoogroups.com
              > > From: buffumjr18@
              > > Date: Wed, 1 May 2013 01:06:23 +0000
              > > Subject: [7x10minilathe] Chuck Grinding
              > >
              > >
              > >
              > >
              > >
              > >
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              > >
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              > >
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              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > >
              > > I have seen this mentioned in Home Shop Machinist, Machinists Worksghop, and some Lindsay books. Well, I had built a tool post grinder last year, so I thot I'd give it a try.
              > >
              > >
              > >
              > > Before I did, here are the runouts.
              > >
              > >
              > >
              > > Craftsman 3 jaw chuck
              > >
              > > .0033 at the chuck
              > >
              > > .013 at 9"
              > >
              > >
              > >
              > > Chinese "Semi-Steel" 6" 4 jaw
              > >
              > > N/A at the chuck. You "dial in" a 4 jaw.
              > >
              > > .038" at 9"
              > >
              > >
              > >
              > > After
              > >
              > >
              > >
              > > Craftsman
              > >
              > > .0015 at the jaws
              > >
              > > .020" at 9"
              > >
              > >
              > >
              > > Chinese 4 jaw
              > >
              > > .015 at 9"
              > >
              > >
              > >
              > > On all 4 9" measurements, I loosened the jaws, and rotated the round rod 90°, then retightened. In the case of the 4 jaw, redialed in. The defelection did not follow the side of the rod.
              > >
              > >
              > >
              > > I didn't use a forcing ring. I set the lathe to rotate as fast as it would go. The centrifugal force nearly duplicated the distortion of a load.
              > >
              > >
              > >
              > > By golly, it worked just like they said it would. I'm not getting collet-like accuracy, but it isn't as annoyingly off as it was.
              > >
              >
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