Miller Electric

Welding Discussion Forums

Home » Resources » Communities » Welding Discussion Forums

The forum is currently undergoing maintenance and is in a 'read-only' mode for the time being. Sorry for the inconvenience.


  • If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Announcement

Announcement Module
Collapse
No announcement yet.

Aluminum Tig ? for the pros or whoever

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • Aluminum Tig ? for the pros or whoever

    I'll try to explain without pics..... I have a 6" diameter aluminum disk x .125 thick. I also have a 6" ID x .125 wall aluminum tube. The disk will fit into the
    end of the tube flush with the end. It's a snug fit. I want to tig these together. I also want the weld to be flush. Do I v taper the inside of the tube
    and taper the disk so when they come together there will be a V to fill and then grind flush. This has to be perfect. It will be spinning about 1000 rpm
    What sequence... do I spot, then weld to have it stay true? Explain. This is the gear enclosure for my helicopter project that will hold oil..
    KB hellllllllllllllllllllp!!
    Thanks ..............................Nick

  • #2
    It will work the way you are describing with the "v" groove. Six long tacks (about 1" each) evenly spaced & then weld it up.

    Comment


    • #3
      You can also line up the inside corner of the plate with the inside corner of the tube so will have an "outside corner weld". This leaves you with a nice area to fill up with weld & less sanding.

      Comment


      • #4
        +1 for the outside corner idea. Also it might not be a bad idea to leave a 1/16" gap or so to make sure you get good penetration into the joint, because welding both sides would be difficult given the tight space inside the tube. A gap will make it easier to make it not leak as well.
        The outside corner could be "trued" in a lathe, without removing much of the weld, leaving a stronger joint in the end.

        If you need help, I'd be glad to lend a hand. I love projects like this, and it makes it even better that it's for a helicopter.

        Later,
        Kev

        Comment


        • #5
          I understand the corner but the end plate is only 1/8" thick and it would be difficult to extend it out of the tube to make a corner joint and keep it square with the tube. As far as the gap idea which is good..............I have the problem of keeping the disk centered in the tube without elaborate jigging. This needs to run very true as it spins. The tube is about 5" deep
          so welding is out..... at least for me it is.

          Another question.......The tube will have about 3" of oil in it. I'm torn between
          thinking the oil will be slung to the outside and not having lube in the center where it is needed...............but I'm also thinking the oil can't really grab the walls of the tube and will never reach the speed/force to totally stay at the outside wall. What are your ideas? I guess I need to spin a can with liquid in it and see the results. I might be going with the second thought.
          thanks for the replies.
          Nick

          Comment


          • #6
            I just made a model with a cordless drill and a plastic cup with water.

            The water spins to the outside wall alright! That was only at about 200 rpm. Any faster and the water would have climbed out the top.

            I also like the idea of a corner joint/weld. Accuracy in fit-up is no problem, just use three spacers exactly the same length on the inside at 120 deg.

            Comment


            • #7
              Tack it up evenly spaced around the diameter taping it into place as you go, Spread your heat out too. Tack one side then the other. you could set the tube upright one end over and other 5" tube or pipe this would hold and support the end cap as you weld.

              Penetration should not be and issue with 1/8" material, Blow through maybe but not lack of penetration.

              I've done jobs like this before where you just have to shim everything to fit.
              It can be done and no elaborate fixture required.

              And 1000 RPM's is not that fast considering it's weight. If you were off and 1/8" on the weld you would never see any vibration 3000 rpm maybe but not 1000.
              And yes oil will stick to the side of the tube two ways to over come this with out lowering the speed is one use thinner oil or two use more oil.

              Exactly what is this thing going to be????
              Last edited by kcstott; 09-11-2008, 06:24 PM.

              Comment


              • #8
                Originally posted by kcstott View Post
                Exactly what is this thing going to be????
                "This is the gear enclosure for my helicopter project that will hold oil.. "

                Comment


                • #9
                  Nick, how about some more details for the curiosity in all of us? You know we can't possibly do this job justice until we know all the details...

                  Comment


                  • #10
                    Originally posted by Marcel Bauer View Post
                    Nick, how about some more details for the curiosity in all of us? You know we can't possibly do this job justice until we know all the details...
                    See "Flying Project" thread I started on 8-08. Pics there of the rotor head
                    I'm making.

                    Comment


                    • #11
                      Think about how a torque converter works on a car. Centrifugal force creates enough fluid drag via pressure to propel your vehicle. Inside the spinning tube will be no different.

                      I think the solution would be to use a heavier oil (sticks to things better) and then have the gears protrude into where the oil is being held on the sides of the tube to splash it around, or at least become bathed in it as it passes through.

                      Too much, or too thick of oil will cause excessive resistance (especially cold) that will waste engine power, so that's another concern to think about.

                      And, yes, I am aware thinner oil lubricates better.

                      Comment


                      • #12
                        I believe a torque converter has blades/fins like a turbine. Mine doesn't. I'm sure some of the lube will be slung outwards but the oil toward the center will not have as much speed. I feel it will be like a whirlpool as viewed from above.
                        Now if it had BBs instead of oil, it would be a lot worse situation. Just my thoughts.
                        Last edited by monte55; 09-12-2008, 01:48 PM.

                        Comment


                        • #13
                          Nick, you missed the point. The oil is still being slung against the outside wall with the same force. You're simply not taking advantage of the pressure like a converter does.

                          Whatever started in the middle will end up held firmly against the outside wall at your 1000rpm. Like I said before, your best bet (IMO) is to design the gearbox so that the oil layer is thick enough on the outside of the housing to encounter the gears path. This is a simple calculation of volume distributed about the ID of the tube.

                          Comment


                          • #14
                            Originally posted by Fishy Jim View Post
                            Nick, you missed the point. The oil is still being slung against the outside wall with the same force. You're simply not taking advantage of the pressure like a converter does.

                            Whatever started in the middle will end up held firmly against the outside wall at your 1000rpm. Like I said before, your best bet (IMO) is to design the gearbox so that the oil layer is thick enough on the outside of the housing to encounter the gears path. This is a simple calculation of volume distributed about the ID of the tube.
                            Ok.........Fishy Jim gets a blue star next to his name. I did a test where I took a 2.5" diameter x 3.5" tall transparent plastic measuring cup with plumb
                            side walls. Drilled a hole in the bottom, ran a bolt through to chuck in a drill, put in about 1" of water and started spinning. True, the fluid will move to the outside of the container. I knew this would happen. At lower speeds the
                            fluid would dish in the middle and some ride up on the walls. As the speed increased to probably the rpms I'll turn, the fluid dish would move down untill the center bottom was absent of fluid. I figured fluid would be slung out but I didn't think the center would clear that much. I'm not sure of exact rpms, only what is on drill side...0-350 & 0-1100 rpm. Now this test is with a smooth bottom and nothing in the fluid path which allows it to get up to
                            speed. Different viscosity fluids may react a little differently according to their weight and speed. They may do exactly the same but take a little longer to get there. Now.........at the higher speed the fluid at the wall side wanted to creep up and be slung out the top. Not good. I placed a rubber donut in the top of the container. Now when I spin it up, the fluid wall thickness being thinner than the donut, kept all fluid inside. I feel an inside
                            ring thicker than the fluid wall will be and a slinger disk over that should keep all fluid inside even though it's not really sealed at the top. I'm going to put some dye in the water and do more tests.

                            Comment


                            • #15
                              It's part of any first semester physics class.

                              Comment

                              Working...
                              X
                              Special Offers: See the latest Miller deals and promotions.