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3771Re: [southbend10k] Knurling Issues

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  • viajoaquin@aol.com
    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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