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How do I make this shape?

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  • #16
    Don't know if it's been mentioned yet but you should probably Google "Melting point of aluminium" and "exhaust gas temperature".

    Read somewhere someone tried this and the end result was a failure.

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    • #17
      Originally posted by oxford View Post
      If you do it out of sheet and are worried about the weld seem not matching when polished, just get some small strips sheared out of the same sheet for filler. It will match perfectly when ground down and polished.

      That is something worth a try! I'll try this out on some scrap and see what happens.


      Originally posted by Mech View Post
      Don't know if it's been mentioned yet but you should probably Google "Melting point of aluminium" and "exhaust gas temperature".

      Read somewhere someone tried this and the end result was a failure.
      I have been building aluminum exhausts for cars for years now without any problems.





      And bikes too.

      Andy

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      • #18
        Finally got at making up this exhaust "shape" today. It was actually easier than I expected. Two press operations, one strait onto the pipe to squish it and make it oval, the second op to squish just one side of the oval down to more of a V shape. It took me much longer and was more difficult to polish the pipe to an exceptionable state. I would like it to be like a mirror but that is hard to get in aluminum and then it wouldn't match the other mediocre polishing I did on the other parts.



        Andy

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        • #19
          That looks great. A lot nicer than the castings it mates up with.
          Location: Long Island, N.Y.

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          • #20
            I used to have an old reynolds aluminium catalogue, if i remember right the shape you show was very very similar to one of their standard extrusions, available in a number of alloys, either it was for light aircraft, or yachts, might be worth sending a drawing to as many extruders as you can, even if its not a standard die they may have a custom die similar (custom meaning owned by a customer), normally they will tell you who has it so you can buy lengths off their die, you don't want to be buying a die! Big port hole single cavity dies are expensive, i.e. thousands.
            Im betting what you need is out there somewhere
            Even if you hydro form it your still going to need a die, hydraulic power pack hoses etc, we tried freeze forming in the 70s the cavity filled with water, frozen to expand the annealed Ali into the shape, the good thing was the low temperature stopped the Ali age hardening, aircraft rivets were kept refrigerated too, mind that was with Duralumin an Ali copper alloy.
            We did burst a few dies too till we discovered that putting an 1" diameter hole in the die allowed the Ali to blow without busting the former.
            Mark

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            • #21
              Originally posted by RichR View Post
              That looks great. A lot nicer than the castings it mates up with.
              Are you suggesting I sand down and polish the castings now?

              Originally posted by boslab View Post
              I used to have an old reynolds aluminium catalogue, if i remember right the shape you show was very very similar to one of their standard extrusions, available in a number of alloys, either it was for light aircraft, or yachts, might be worth sending a drawing to as many extruders as you can, even if its not a standard die they may have a custom die similar (custom meaning owned by a customer), normally they will tell you who has it so you can buy lengths off their die, you don't want to be buying a die! Big port hole single cavity dies are expensive, i.e. thousands.
              Im betting what you need is out there somewhere
              Even if you hydro form it your still going to need a die, hydraulic power pack hoses etc, we tried freeze forming in the 70s the cavity filled with water, frozen to expand the annealed Ali into the shape, the good thing was the low temperature stopped the Ali age hardening, aircraft rivets were kept refrigerated too, mind that was with Duralumin an Ali copper alloy.
              We did burst a few dies too till we discovered that putting an 1" diameter hole in the die allowed the Ali to blow without busting the former.
              Mark

              I believe it was aircraft spruce I was looking at that had the extrusions in the shape I was looking for however the size was off just enough that it wouldn't work well for me. They called them "struts" I assume for the landing gear of a plane. Their strut extrusions were either 1/4 to wide or 1/4 to wide the other way.

              I just ended up getting some round 2" tube with the right wall thickness that would fit right around the top casting and inside the lower casting of the motor. It was surprisingly easy to just press the tube into the shape I needed.
              Andy

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              • #22
                Are you suggesting I sand down and polish the castings now?
                Dealers choice. Maybe paint the bottom casting to match the lower unit.
                Location: Long Island, N.Y.

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                • #23
                  Just spray it all dayglow orange.
                  Paul A.
                  SE Texas

                  And if you look REAL close at an analog signal,
                  You will find that it has discrete steps.

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                  • #24
                    Originally posted by Paul Alciatore View Post
                    Just spray it all dayglow orange.
                    Top to bottom prop plug wire spark plug and all? I could put it on craigslist listed with fresh paint.
                    Andy

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                    • #25
                      Looks really nice! But I think you'll need a lot more horsepower to get that workbench up on plane...

                      Oh, the strut material is for wing struts.

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                      • #26
                        Originally posted by Wayne Sippola View Post
                        Looks really nice! But I think you'll need a lot more horsepower to get that workbench up on plane...

                        Oh, the strut material is for wing struts.


                        Thats what the others are for!





                        The wings makes more sense than suspension. I was thinking it was quite thin of material for wheel suspension.
                        Andy

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                        • #27
                          They have that shape in several sizes for sailboat masts too.
                          Kansas City area

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                          • #28
                            Yeah, but sailboat masts have a slot for the hanks of the mainsail.
                            Location: Long Island, N.Y.

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