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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
      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

      "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."- Benjamin Franklin, Historical Review of Pennsylvania, 1759

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    • Nick Andrews
      Actually I was quite surprised at how tight the fit actually is. Not much wiggle in these clamps.
      Message 2 of 27 , Jun 22, 2013

        Actually I was quite surprised at how tight the fit actually is.  Not much wiggle in these clamps.

        On Jun 22, 2013 2:26 PM, "David G. LeVine" <dlevine@...> wrote:
         

        On 06/21/2013 11:30 PM, Nick Andrews 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.

        For short sections, this sounds good.

        The accuracy will be pretty poor, however.

        Dave 8{)

        --

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

        Bill Cosby

      • 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 3 of 27 , Jun 22, 2013

          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 4 of 27 , Jun 24, 2013
            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 5 of 27 , Jun 24, 2013
              ------------------------------
              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 6 of 27 , Jun 25, 2013
                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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