Looking for air cylinder with a hollow ram

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  • Carld
    Senior Member
    • Aug 2006
    • 6061

    Looking for air cylinder with a hollow ram

    I need an air cylinder with a hollow threaded ram for a machine I need to modify. It has to be double acting. I can't seem to find anything with a hollow ram, is there such a critter?
    It's only ink and paper
  • lane
    Senior Member
    • Aug 2005
    • 2691

    #2
    Check with SMC I seemed to remember using one from them years ago. Sorry I do not have a link.
    Every Mans Work Is A Portrait of Him Self
    http://sites.google.com/site/machinistsite/TWO-BUDDIES
    http://s178.photobucket.com/user/lan...?sort=3&page=1

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    • Doozer
      Junior Member
      • Jan 2005
      • 10595

      #3
      Bimba.

      --Doozer
      DZER

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      • Carld
        Senior Member
        • Aug 2006
        • 6061

        #4
        I have looked on about 10 web sites and just gave up and figured someone here may have seen or used one.

        I guess I will have to go back and email or call each company. Oh well, it's sure easier now than it was 20 years ago. All we had was the Thomas books and now we have the net and ThomasNet.com

        Geez, I hate making all those calls and emails and then end up making the cylinders myself. Since they have to fit into a compact area I suppose I'll be making them.
        It's only ink and paper

        Comment

        • Ken_Shea
          Senior Member
          • Aug 2006
          • 2591

          #5
          Have 10 or 12 various size and makes of air cylinders, none have hollow rams, Carl, is the length such that it would prohibit drilling?

          oops, over lap


          Curious, what would be the use of one with a hollow ram?

          Comment

          • JCHannum
            Senior Member
            • Nov 2001
            • 10091

            #6
            Lane's memory of SMC is a good place to start. Check the Yellow Pages for pneumatics & hydraulics suppliers in your area. There are a lot of options available that might not show up in an on line catalog search.

            Does the ram need to be hollow the full length, or just female threads? I have a 4" X 3/4" pancake cylinder here with a deep 1/2" female thread on each end. It could probably be drilled through a smaller diameter for air flow. The problem with a through bore is the method used to attach the piston. If retaining rings are used, the diameter of the piston rod is reduced in this area.
            Jim H.

            Comment

            • Carld
              Senior Member
              • Aug 2006
              • 6061

              #7
              It's going on a welding table that rotates to tig weld tubes. I made some 3 piece collets to hold the tube so the screws don't deform the tubing. I uses 3/4" all thread for the screws and they have to screw them in and out a lot to remove the tubing. The boss got the idea of using air cyl. to move it in and out after they get it adjusted.

              Now I have to figure out how to make it all come together. I'm not sure just how much stroke I will need but at least 2" on each cyl, maybe 3" to clear the flange on the tube.

              If I make the cyl. I can shrink fit the piston on the shaft and use a double lip seal to seal both directions. Seals on the ends of the shaft is no problem.

              The problem is the length and OD of the outside of the cyl. and I am not even sure if all this will work. It's a work in process but sure would like to find a cyl. the size I need. I don't think they will like the cost of doing this.

              I am also looking at simpler ways to back the collets off and I have some ideas there.
              It's only ink and paper

              Comment

              • mechanicalmagic
                Senior Member
                • Oct 2007
                • 441

                #8
                Have you looked at Enerpac hollow Hydraulic cylinders?

                They seem to have many sizes.

                Comment

                • John Stevenson
                  Senior Member
                  • Mar 2001
                  • 16177

                  #9
                  Carl, when I have wanted something similar in the past I have finished up modifying an existing cylinder, in fact the last one I needed which was 6" diameter but only 1 1/2" stroke i just bought the tube from the local SMC agent and cast the two end plates as they needed to be very thick to carry part of the machine on them.

                  In my case it was easier to have them cast instead of machining them out of 7" square alloy bar which I didn't have anyway.



                  The cylinder is just visible at the top of this machine.

                  .
                  .

                  Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                  Comment

                  • Carld
                    Senior Member
                    • Aug 2006
                    • 6061

                    #10
                    He wants to use air but I'm not locked on just air.

                    John, I am hoping to just modify an existing cyl. and I will check the sites suggested and some of the sites I found.
                    It's only ink and paper

                    Comment

                    • TGTool
                      Senior Member
                      • Aug 2005
                      • 3613

                      #11
                      Originally posted by Carld
                      He wants to use air but I'm not locked on just air.

                      John, I am hoping to just modify an existing cyl. and I will check the sites suggested and some of the sites I found.
                      You can use air on hydraulic cylinders if you find one that otherwise fits your needs. OTOH, the hydraulic cylinder could give you the force you need in a smaller package. Air over oil might be an option at the detriment of more parts and cost.
                      .
                      "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

                      Comment

                      • Black_Moons
                        Senior Member
                        • Aug 2009
                        • 9096

                        #12
                        Have you considered other methods to move bar?

                        Like say, a pnumatic cylinders on either side of the bar?

                        Id think the simplest non binding setup would be 2 cylinders to move it forward and back, and another 2 to actuate a clamp.
                        Of course if you only need to move one way, some kind of spring loaded knurled (rubber coated?) eccentric shaft could be used to make a simple (automaticly adjusting to diffrent diamiter) one way clamp.
                        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

                        Comment

                        • Carld
                          Senior Member
                          • Aug 2006
                          • 6061

                          #13
                          Spring loaded return would work and I have that in mind. One problem is I only have an area of about 6" long x 2" square to contain the cylinder in. Nothing can stick out to hang on the welders hands, arms or clothing and there is shields around the rotating table to deal with.

                          The more I have thought about this and read suggestions here. It may have to be a spring loaded cyl. for simplicity and compactness and I will probably have to make the cyl.
                          Last edited by Carld; 12-27-2009, 11:48 AM.
                          It's only ink and paper

                          Comment

                          • Black_Moons
                            Senior Member
                            • Aug 2009
                            • 9096

                            #14
                            they make VERY small cylinders if the force required is low enough, like 1" diamiter is common.
                            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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