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Knurling Issues

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  • Jim B.
    I note that there has not been a post here for over a month. So here is what I have been doing for a while. In my restoration of the South-Bend drill press,
    Message 1 of 4 , Nov 19, 2010
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      I note that there has not been a post here for over a month.
      So here is what I have been doing for a while.
      In my restoration of the South-Bend drill press, the thumbwheels that set the
      quill stops needed work. There were only two, there should be three. One of the
      remaining ones was well buggered.
      I needed to make some. The thumbwheel is 1-1/4 in OD 1/4" thick at the knurl
      and has a 1/2 NC thread. The OD has a straight knurl and there are 80 groves in
      the OD. This corresponds to a 64 pitch knurl.
      http://i50.photobucket.com/albums/f334/eeengineer1/SB-DP-nut.jpg
      The two knurling tools I have for my QC TP had diamond knurls in them. I started
      looking for a matching knurl and found most to be expensive.
      I wound up getting a pair of 36 tooth 3/4" diameter, knurls from the UK for
      about $10.
      That's equivalent to the 48 pitch knurl, a bit coarse.
      I loaded the knurls into one of the holders and I decided to test thing out.
      I tool a piece of CRS scrap 1/2" and tried it out. Results were crap. I then
      tried a good piece of OD ground 1144 stock. Remember The OD matches the knurl,
      more or less.
      http://i50.photobucket.com/albums/f334/eeengineer1/Straight-knurl.jpg
      What I got was ill formed knurls that would randomly change from 48 pitch to 96
      pitch without reason. The picture shows one of each. BTW see that little diamond
      knurled thumbwheel? That was made from the original piece of CRS.
      I thought: "Perhaps the two wheels are not synchronizing up". I started
      knurling, with one knurl on center. I even tried a piece of brass.
      http://i50.photobucket.com/albums/f334/eeengineer1/Straight-knurl.jpg
      Still ugly and double cut.
      Based on somebody's suggestion I spend several hours honing the knurl (it did
      need it).
      I got tired of making 3/4" thumbscrews and tried larger stock suitable for the
      1-1/4" thumbwheels. This was a piece of 1-5/16 stock
      http://i50.photobucket.com/albums/f334/eeengineer1/1-1_4-double-cut-1.jpg
      Double cut a gain but better looking.
      Going to Machineries' Handbook and reading the knurling section, they state that
      diameter is important. I carefully turned the OD to 1.25, I had not done that
      the first time.
      I died the face and brought the knurl lightly into contact. I went one turn plus
      just a bit.
      http://i50.photobucket.com/albums/f334/eeengineer1/dye-marking-1250-diam.jpg
      You can see that the knurl is very close to falling on itself. Over the next
      three knurls I refined the OD just a bit. 0.0025 under 1-1/4 is perfect.
      I was now able to get consistent single knurls and finish the job.
      http://i50.photobucket.com/albums/f334/eeengineer1/All-three.jpg

      Proving that size does matter.





      Jim B.
      Owner
      southbendheavy10@yahoogroups.com
      co-owner.
      NJ_LoganLatheOwners@yahoogroups.com
    • Bob Wright
      Those are really nice Jim thanks for posting. I haven t tore into my SB drill press yet...Bob
      Message 2 of 4 , Nov 19, 2010
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        Those are really nice Jim thanks for posting. I haven't tore into my SB drill press yet...Bob
      • viajoaquin@aol.com
        Jim, Nice job! Makes perfect sense but I would never have thought about it until I got the same crappy results. Something to keep in the back of my mind in the
        Message 3 of 4 , Nov 19, 2010
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          Jim,
          Nice job! Makes perfect sense but I would never have thought about it
          until I got the same crappy results. Something to keep in the back of
          my mind in the event I do some knurling.
          Now, given you have the exact diameter for a successful knurl and know
          the number of teeth of the tool, you should be able to use pi to
          determine the next successful larger or smaller diameter.
          BakoRoy


          -----Original Message-----
          From: Jim B. <btdtrf@...>
          To: southbend10k <southbend10k@yahoogroups.com>
          Sent: Fri, Nov 19, 2010 3:27 pm
          Subject: [southbend10k] Knurling Issues


          I note that there has not been a post here for over a month.
          So here is what I have been doing for a while.
          In my restoration of the South-Bend drill press, the thumbwheels that
          set the
          quill stops needed work. There were only two, there should be three.
          One of the
          remaining ones was well buggered.
          I needed to make some. The thumbwheel is 1-1/4 in OD 1/4" thick at the
          knurl
          and has a 1/2 NC thread. The OD has a straight knurl and there are 80
          groves in
          the OD. This corresponds to a 64 pitch knurl.
          http://i50.photobucket.com/albums/f334/eeengineer1/SB-DP-nut.jpg
          The two knurling tools I have for my QC TP had diamond knurls in them.
          I started
          looking for a matching knurl and found most to be expensive.
          I wound up getting a pair of 36 tooth 3/4" diameter, knurls from the UK
          for
          about $10.
          That's equivalent to the 48 pitch knurl, a bit coarse.
          I loaded the knurls into one of the holders and I decided to test thing
          out.
          I tool a piece of CRS scrap 1/2" and tried it out. Results were crap. I
          then
          tried a good piece of OD ground 1144 stock. Remember The OD matches the
          knurl,
          more or less.
          http://i50.photobucket.com/albums/f334/eeengineer1/Straight-knurl.jpg
          What I got was ill formed knurls that would randomly change from 48
          pitch to 96
          pitch without reason. The picture shows one of each. BTW see that
          little diamond
          knurled thumbwheel? That was made from the original piece of CRS.
          I thought: "Perhaps the two wheels are not synchronizing up". I started
          knurling, with one knurl on center. I even tried a piece of brass.
          http://i50.photobucket.com/albums/f334/eeengineer1/Straight-knurl.jpg
          Still ugly and double cut.
          Based on somebody's suggestion I spend several hours honing the knurl
          (it did
          need it).
          I got tired of making 3/4" thumbscrews and tried larger stock suitable
          for the
          1-1/4" thumbwheels. This was a piece of 1-5/16 stock
          http://i50.photobucket.com/albums/f334/eeengineer1/1-1_4-double-cut-1.jpg
          Double cut a gain but better looking.
          Going to Machineries' Handbook and reading the knurling section, they
          state that
          diameter is important. I carefully turned the OD to 1.25, I had not
          done that
          the first time.
          I died the face and brought the knurl lightly into contact. I went one
          turn plus
          just a bit.
          http://i50.photobucket.com/albums/f334/eeengineer1/dye-marking-1250-diam.jpg
          You can see that the knurl is very close to falling on itself. Over the
          next
          three knurls I refined the OD just a bit. 0.0025 under 1-1/4 is
          perfect.
          I was now able to get consistent single knurls and finish the job.
          http://i50.photobucket.com/albums/f334/eeengineer1/All-three.jpg

          Proving that size does matter.





          Jim B.
          Owner
          southbendheavy10@yahoogroups.com
          co-owner.
          NJ_LoganLatheOwners@yahoogroups.com





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        • Jim B.
          Yes that s true. I started at 1.250, then, I copied the picture into Auto Sketch and scaled the width so it was 2.500 wide. I measured the distance between
          Message 4 of 4 , Nov 19, 2010
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            Yes that’s true.

             

            I started at 1.250, then, I copied the picture into Auto Sketch and scaled the width so it was 2.500” wide. I measured the distance between marks and decided I needed 1.245”, that went the other way. I split the difference and went to 1.27 and it overlayed.

            However the difference in the knurl was not noticeable.

            If you are too far off it will double knurl. How much I don’t know. I ran out of stock.

             

            Jim B.
            Owner
            southbendheavy10@yahoogroups.com
            co-owner.
            NJ_LoganLatheOwners@yahoogroups.com

            Jim,
            Nice job! Makes perfect sense but I would never have thought about it
            until I got the same crappy results. Something to keep in the back of
            my mind in the event I do some knurling.
            Now, given you have the exact diameter for a successful knurl and know
            the number of teeth of the tool, you should be able to use pi to
            determine the next successful larger or smaller diameter.
            BakoRoy

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