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Re: [multimachine] quality of threaded rod

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  • Steve Wan
    Hi Dave Thanks! I discovered the differences earlier. Lucky did not buy it to swap Metric for Imperial nut for the leadscrew. Nick s idea getting a G-clamp and
    Message 1 of 27 , Jun 22, 2013
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      Hi Dave
       
      Thanks! I discovered the differences earlier. Lucky did not buy it to swap Metric for Imperial nut for the leadscrew. Nick's idea getting a G-clamp and cutting it. Usually leadscrews are far more longer unless a shorter one.
       
      Steve Wan

      On Sat, Jun 22, 2013 at 11:30 AM, Nick Andrews <nickjandrews@...> wrote:


      Speaking of cheap sources of ACME-ish threaded rod, how about Harbor Fright (or better) C-clamps?  They are usually on sale for half price and the 5" clamp has at least a 6" long threaded piece, plus I bet you could cut the clamp and have a ready-made 'nut' for it to weld onto a project or bracket.


      On Fri, Jun 21, 2013 at 9:10 PM, David G. LeVine <dlevine@...> wrote:
      On 06/18/2013 11:17 PM, Steve Wan wrote:
      Speaking of square threads or acme threads, any idea where's the supplier?
      Having problems find it on the net.
      
      Note: Acme threads come in either inches or metric.
      
      Steve Wan

      Sorry, Steve, but Acme is a specific thread for Imperial dimensions, the Metric equivalent, trapezoidal, has a slightly different profile.  See http://www.roton.com/trapezoidal-lead-screws.aspx?line=Trapezoidal and http://www.roton.com/acme-lead-nav.aspx?line=Acme for a discussion.

      Since there are different classes and accuracies, as well as different surface hardnesses, I can't give you all the vendors, there are thousands.  Try going to Use-Enco.Com and looking for COMPONENTS    THREADED ROD & STUDS    ACME THREADED ROD, there are some 338 different sizes there.

      Dave  8{)

      --

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

      Bill Cosby



      --
      Nick A

      "You know what I wish?  I wish that all the scum of the world had but a single throat, and I had my hands about it..."  Rorschach, 1975

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    • Pierre Coueffin
      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
      Message 2 of 27 , Jun 22, 2013
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        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.

      • 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 3 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 4 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 5 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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