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Re: screw loading

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  • mattdbartlett
    Machinist handbook has a whole chapter on the subject, unfortunately no simple chart. As I recall, the rule of thumb is 3 full threads of engagement. As far as
    Message 1 of 7 , Feb 1, 2012
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      Machinist handbook has a whole chapter on the subject, unfortunately no simple chart. As I recall, the rule of thumb is 3 full threads of engagement.

      As far as actual load, I think it's more of a question of what you are threading into. Aluminum will hold less of course than steel. If you have a copy of MH, there are equations in there for calculating minimum engagement and max load.

      -Matt



      --- In mill_drill@yahoogroups.com, Jerry Durand <jdurand@...> wrote:
      >
      > Anyone have a link to a good chart for recommended thread engagement and
      > holding capacity for screws? Especially the smaller ones like M3.
      >
      > --
      > Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
      > tel: +1 408 356-3886, USA toll free: 1 866 356-3886
      > Skype: jerrydurand
      >
    • Jerry Durand
      This is to hold some TDK power supplies inside a NEMA 12 box. Their supplies are nice but their mounting is questionable, the supply weighs 4.5 pounds and has
      Message 2 of 7 , Feb 1, 2012
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        This is to hold some TDK power supplies inside a NEMA 12 box. Their
        supplies are nice but their mounting is questionable, the supply weighs
        4.5 pounds and has only three M3 screws that can penetrate up to 3mm
        into the box. Screwed into a pressed-in steel insert like these
        http://www.experiencerc.com/store/images/0012-2.gif

        I'm thinking of some of the thin double stick tape between the supply
        and the case in addition to the screws, these have to go on theatrical tour.

        On 2/1/2012 10:09 AM, mattdbartlett wrote:
        > Machinist handbook has a whole chapter on the subject, unfortunately no simple chart. As I recall, the rule of thumb is 3 full threads of engagement.
        >
        > As far as actual load, I think it's more of a question of what you are threading into. Aluminum will hold less of course than steel. If you have a copy of MH, there are equations in there for calculating minimum engagement and max load.
        >
        > -Matt
        >
        >

        --
        Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
        tel: +1 408 356-3886, USA toll free: 1 866 356-3886
        Skype: jerrydurand
      • Druid Noibn
        Hi, Often the the manufactures rely on and require metal-to-metal contact to conduct the heat away.  I do not know this particualr unit nor how much it/they
        Message 3 of 7 , Feb 1, 2012
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          Hi,
           
          Often the the manufactures rely on and require metal-to-metal contact to conduct the heat away.  I do not know this particualr unit nor how much it/they will be loaded.
           
          Kind regards,
          DBN

          --- On Wed, 2/1/12, Jerry Durand <jdurand@...> wrote:

          From: Jerry Durand <jdurand@...>
          Subject: Re: [mill_drill] Re: screw loading
          To: mill_drill@yahoogroups.com
          Date: Wednesday, February 1, 2012, 1:54 PM

           
          This is to hold some TDK power supplies inside a NEMA 12 box. Their
          supplies are nice but their mounting is questionable, the supply weighs
          4.5 pounds and has only three M3 screws that can penetrate up to 3mm
          into the box. Screwed into a pressed-in steel insert like these
          http://www.experiencerc.com/store/images/0012-2.gif

          I'm thinking of some of the thin double stick tape between the supply
          and the case in addition to the screws, these have to go on theatrical tour.

          On 2/1/2012 10:09 AM, mattdbartlett wrote:
          > Machinist handbook has a whole chapter on the subject, unfortunately no simple chart. As I recall, the rule of thumb is 3 full threads of engagement.
          >
          > As far as actual load, I think it's more of a question of what you are threading into. Aluminum will hold less of course than steel. If you have a copy of MH, there are equations in there for calculating minimum engagement and max load.
          >
          > -Matt
          >
          >

          --
          Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
          tel: +1 408 356-3886, USA toll free: 1 866 356-3886
          Skype: jerrydurand

        • Jerry Durand
          Fan cooled,1000W, so I would like to transfer heat to the enclosure too. In theory it s only 1.5 pounds/screw...at least until you drop it. The previous
          Message 4 of 7 , Feb 1, 2012
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            Fan cooled,1000W, so I would like to transfer heat to the enclosure too.  In theory it's only 1.5 pounds/screw...at least until you drop it.  The previous supply I used was smaller but had 8 M3 screws.  Those have been on tour 2 years now with no failures. 

            Guess I'll just use the screws with some thread-locker so they don't back out.  3mm isn't all that far to have the supply fall out.

            On 2/1/2012 11:10 AM, Druid Noibn wrote:
            Hi,
             
            Often the the manufactures rely on and require metal-to-metal contact to conduct the heat away.  I do not know this particualr unit nor how much it/they will be loaded.
             
            Kind regards,
            DBN


            -- 
            Jerry Durand, Durand Interstellar, Inc.  www.interstellar.com
            tel: +1 408 356-3886, USA toll free: 1 866 356-3886
            Skype:  jerrydurand 
            
          • leasingham_connelly
            I ve added a file with a couple of tables from the ISO metric thread standard. It defines length of thread engagement for metric threads classed as short,
            Message 5 of 7 , Feb 2, 2012
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              I've added a file with a couple of tables from the ISO metric thread standard. It defines length of thread engagement for metric threads classed as short, normal and long. Holding capacity is a function of applied torque and strength of materials so it is not usually given in a table that I have ever been able to find.

              Hope this helps as a starting point.

              Martin

              --- In mill_drill@yahoogroups.com, Jerry Durand <jdurand@...> wrote:
              >
              > Anyone have a link to a good chart for recommended thread engagement and
              > holding capacity for screws? Especially the smaller ones like M3.
              >
              > --
              > Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
              > tel: +1 408 356-3886, USA toll free: 1 866 356-3886
              > Skype: jerrydurand
              >
            • Jerry Durand
              1.5 threads is all an M3 needs? Seems a bit low but I guess the power supply won t fall out, the mounting doesn t inspire confidence. Thanks for the chart,
              Message 6 of 7 , Feb 2, 2012
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                1.5 threads is all an M3 needs? Seems a bit low but I guess the power
                supply won't fall out, the mounting doesn't inspire confidence.

                Thanks for the chart, much better than the old "2 threads is always
                enough" rule which I see is NOT the case.

                On 02/02/2012 06:15 AM, leasingham_connelly wrote:
                > I've added a file with a couple of tables from the ISO metric thread standard. It defines length of thread engagement for metric threads classed as short, normal and long. Holding capacity is a function of applied torque and strength of materials so it is not usually given in a table that I have ever been able to find.
                >
                > Hope this helps as a starting point.
                >
                > Martin
                >
                > -

                --
                Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
                tel: +1 408 356-3886, USA toll free: 1 866 356-3886
                Skype: jerrydurand
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