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  • Service Jack Repair

    I borrowed a service jack from my friend John's son, to help us move the machine tools into the new addition, Just about the time we were finished using it, the jack wouldn't raise, when you pumped the handle. Upon inspection we noticed that the screw that attached the handle to the jack had become dislodged and wedged between the two cans that guided the return springs for the pistons. The threads that had held the screw in place were all stripped out.

    0. Missing handle retention screw
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    When we were pumping the jack the screw was denting and damaging one of the spring guidance cans.

    1. Bent spring guidance can
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    2. Indentation in can
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    Miller Thunderbolt
    Smith Oxyacetylene Torch
    Miller Dynasty 200DX
    Lincoln SP-250 MIG Welder
    Lincoln LE 31 MP
    Lincoln 210 MP
    Clausing/Colchester 15" Lathe
    16" DuAll Saw
    15" Drill Press
    7" x 9" Swivel Head Horizontal Band Saw
    20 Ton Arbor Press
    Bridgeport

  • #2
    The can was originally made by rolling over the edge of a cylinder to trap a washer.
    We decided to make a new can by welding a piece of 1-1/4" EMT conduit to a new washer to simulate the rolled over edge and to use the original washer on top of the new washer. I had to soak the EMT conduit in HCL acid to remove the galvanizing. Next I turned a mandrel on the lathe to allow me to hold the flimsy washer so that I could turn the OD.

    3. Mandrel to machine washer
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    4. Starting to turn washer
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    5. Done turning washer
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    6. Turned Washer
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    Miller Thunderbolt
    Smith Oxyacetylene Torch
    Miller Dynasty 200DX
    Lincoln SP-250 MIG Welder
    Lincoln LE 31 MP
    Lincoln 210 MP
    Clausing/Colchester 15" Lathe
    16" DuAll Saw
    15" Drill Press
    7" x 9" Swivel Head Horizontal Band Saw
    20 Ton Arbor Press
    Bridgeport

    Comment


    • #3
      The next two pictures show the new washer welded to the EMT conduit.

      7. Washer welded to EMT conduit
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      8. Penetration of weld on back side
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      Next I pressed the original washer into the top of the new can.

      9. Original washer installed
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ID:	607121
      Miller Thunderbolt
      Smith Oxyacetylene Torch
      Miller Dynasty 200DX
      Lincoln SP-250 MIG Welder
      Lincoln LE 31 MP
      Lincoln 210 MP
      Clausing/Colchester 15" Lathe
      16" DuAll Saw
      15" Drill Press
      7" x 9" Swivel Head Horizontal Band Saw
      20 Ton Arbor Press
      Bridgeport

      Comment


      • #4
        So the way it works is that the spring pushes on the new can. The new can pushes on the original washer, which has a counter bore on the top which holds a clip ring. The clip ring pushes on a groove in the piston. When you push the jack handle down it compresses a piston, which lifts the load. When you lift the handle up the spring returns the piston to the extended position.

        To solve the root cause of the problem I tapped the hole in the handle with a 3/8"-16 UNC thread and installed a spring plunger the I purchased from McMaster Carr. When the plunger is extended it holds the jack handle in place. When you pull the knob out and rotate the knob 90°, it retracts the plunger, so the handle can be removed.

        10. Spring plunger installed
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        11. Plunger extended
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        12. Knob position for extended plunger
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        13. Knob position for retracted plunger
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        Miller Thunderbolt
        Smith Oxyacetylene Torch
        Miller Dynasty 200DX
        Lincoln SP-250 MIG Welder
        Lincoln LE 31 MP
        Lincoln 210 MP
        Clausing/Colchester 15" Lathe
        16" DuAll Saw
        15" Drill Press
        7" x 9" Swivel Head Horizontal Band Saw
        20 Ton Arbor Press
        Bridgeport

        Comment


        • #5
          The last step was re-assembling the jack with the new spring guidance can. If you didn't know any better, you couldn't tell the new can from the old one.

          14. New can installed
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          And here is the jack all done.

          15. Jack all done
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ID:	607129
          Miller Thunderbolt
          Smith Oxyacetylene Torch
          Miller Dynasty 200DX
          Lincoln SP-250 MIG Welder
          Lincoln LE 31 MP
          Lincoln 210 MP
          Clausing/Colchester 15" Lathe
          16" DuAll Saw
          15" Drill Press
          7" x 9" Swivel Head Horizontal Band Saw
          20 Ton Arbor Press
          Bridgeport

          Comment


          • #6
            Don, thanks for posting! Your beautiful work and outstanding pictures are always a treat! Thank you!

            Comment


            • #7
              Great work, that is why I don't borrow or loan tools, over the year tools have come back broken and guess what the fellow borrowed never notice and did not offer anything to help solve the problem, you are the very, very, rare case, you a good man.

              Comment


              • #8
                Fine work...Bob
                Bob Wright

                Comment


                • #9
                  Good job Don. I’m with you on other people’s tools, I always return them in better condition than I borrowed it.

                  Comment

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