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Re: [multimachine] quality of threaded rod

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  • Bruce Bellows
    Anti backlash nuts can be used to eliminate backlash even on low precision acme thread if that is all that is required. A precision class acme thread will have
    Message 1 of 27 , Jun 24, 2013
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      Anti backlash nuts can be used to eliminate backlash even on low precision acme thread if that is all that is required.

      A precision class acme thread will have a tighter tolerance between the thread pitches.
      For example  10tpi thread 
      2G class has a tolerance of .0095
      3G class has a tolerance of .0044
      2G class has a tolerance of .0032

      Bruce

      On 6/23/2013 1:05 AM, Pierre Coueffin wrote:  

      If you have a disk indicator with a long stroke, it might be interesting to measure how consistent the travel is per revolution of the screw. Also, measuring the play along the axis could be useful.

    • Chris Tofu
      ... Wow, aren t those tolerances huge!? Would definitely need a lot more accuracy to produce a diffraction grating. 100,000 or more threads per inch.
      Message 2 of 27 , Jun 24, 2013
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        On Mon, Jun 24, 2013 7:20 AM PDT Bruce Bellows wrote:

        >A precision class acme thread will have a tighter tolerance between the thread pitches.
        >For example 10tpi thread
        >2G class has a tolerance of .0095
        >3G class has a tolerance of .0044
        >2G class has a tolerance of .0032

        Wow, aren't those tolerances huge!? Would definitely need a lot more accuracy to produce a diffraction grating. 100,000 or more threads per inch.
      • David G. LeVine
        ... No, they are not. Differential accuracy is MUCH better with a preloaded nut. If you move a foot, you could see 0.01 error, while moving a few
        Message 3 of 27 , Jun 25, 2013
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          On 06/24/2013 11:36 AM, Chris Tofu wrote:
          >> A precision class acme thread will have a tighter tolerance between the thread pitches.
          >> >For example 10tpi thread
          >> >2G class has a tolerance of .0095
          >> >3G class has a tolerance of .0044
          >> >2G class has a tolerance of .0032
          > Wow, aren't those tolerances huge!? Would definitely need a lot more accuracy to produce a diffraction grating. 100,000 or more threads per inch.

          No, they are not. Differential accuracy is MUCH better with a preloaded
          nut. If you move a foot, you could see 0.01" error, while moving a few
          thousandths would more likely be in the tenths or hundredths of a
          thousandth range or smaller.

          Dave 8{)

          --

          "A word to the wise ain't necessary - it's the stupid ones that need the
          advice."

          Bill Cosby
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