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  • wave in the cutting

    Hi all

    In 1969 had basic machine shop training for 2 years, lathe, casting, gas welding, sheet metal, spot welding, tool making, and rod iron bending, and tempering steel.
    Not a lot of time on lathe the last lathe test was making a ball bearing by hand.
    After reading May/June 2012 the home shop machinist cutting speed and feed rates figure 2 pages 58 you see a wave in the cutting.
    Do you get this from manual by hand feeding? and would you get this from a flat cutting tool.

  • #2
    The figure you are referring to in the article is illustrating the differences in surface finish that result from differences in a lathe tool’s nose radius.

    In the figure, the lathe carriage is being fed at a rate of .005” per revolution. At this feed rate, the tool marks left on the material will have a .0006” crest when using a tool with a .005” radius. For a tool with a .010” nose radius, the crest height is reduced to .0003”.

    As Sandro mentions in the article, his lathe has limited ability to change feed rates and when he is not getting a fine enough finish in his slowest available feed rate, he can smooth out the finish by increasing the nose radius of his cutter.

    George
    George

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    • #3
      The nose radius and feed rate are not the only factors that effects the surface finish. Here is a post where I showed a very clear difference in the finish that was primarily due to the consistency of the feed rate as provided by an accessory handle that is several times large than the original. I was doing some milling in the lathe, but the same effect is apparent when turning.

      http://bbs.homeshopmachinist.net/sho...h+lathe+handle

      With the larger handle it is much easier to have a consistent feed rate. You really don't know just how irregular the feed rate is with a small crank until you try using something like this. This effect is probably also responsible for the improvement when using power feed as power feed will be very consistent.
      Last edited by Paul Alciatore; 05-16-2012, 04:42 PM.
      Paul A.

      Make it fit.
      You can't win and there is a penalty for trying!

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      • #4
        Finish off with a single cut fine file and "wet and dry" cutting paper.

        What ever does the job does the job.

        Technique is importand here.

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        • #5
          Originally posted by oldtiffie
          Finish off with a single cut fine file and "wet and dry" cutting paper.

          What ever does the job does the job.

          Technique is importand here.
          Right on right on.
          Every Mans Work Is A Portrait of Him Self
          http://sites.google.com/site/machinistsite/TWO-BUDDIES
          http://s178.photobucket.com/user/lan...?sort=3&page=1

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