Announcement

Collapse
No announcement yet.

Thread or shrink?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Thread or shrink?

    I'm looking for advice with regards to joining 2 pieces of1.5inch hydraulic ram. My problem is that the rod in the ram is longer than standard by 3". My original idea was to cut the 3" off the old rod and the drill and thread it and screw in onto the new rod. It has been suggested that it would be better to drill it and machine the new rod to .005" over the size of the hole and then heat the piece with the hole to expand it. Slip it on and let it shrink fit. This would alieviate any tendancy to unscrew and may make it easier to guarantee the rod ends up straight.
    The extension doesn't pass through the seals and the ram is single acting only lifting.
    Would .005" be enough and would heating in the household oven achieve the temperature needed to get the neccessary expansion?
    I look forward to your opinions.
    Cheers.
    Ian

  • #2
    Personally, I would still thread it...If your worried about unscrewing then you should loc-tite it or set screw it...I wouldn't go a .005 interference if you plan to shrink fit...I would go about .002 interference...it will never come undone..

    brent

    Comment


    • #3
      Threading it is the way to go with a job like this.
      To invent, you need a good imagination - and a pile of junk. Thomas A. Edison

      Comment


      • #4
        .002 is plenty for steel to steel,you may be better off freezing the small end in liquid nitrogin or CO 2.for insertion. That way your not in danger of weakening you ram from the heat.
        AJ

        Comment


        • #5
          Wato,

          For what you describe I would take the easiest approach. Machine a hole in both pieces, make a close fitting steel pin to go in both and loctite in place. It's under compression, it will stay put.
          Free software for calculating bolt circles and similar: Click Here

          Comment


          • #6
            Turn a .5 to .750 long boss on one and ream a hole .001 under size on the other. Press together making sure sholders contact. Drill and ream appropriate size cross hole through both and press a dowel pin in the hole to secure.

            Comment


            • #7
              Thanks for all the ideas. I went down the shrink fit path mainly because I didn't have the gear to make the internal thread and was a 2 week wait to get taps to suit. The joys of living in the country. Anyway all went well and the ram is working well. Now just need the rain to get the crop in the ground. I'll need to remember all the great ideas you gave me as this type of situation has come up before and no doubt will again.
              Cheers.
              Ian

              Comment

              Working...
              X