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Thread: Daydreaming about making headers - what tools and fabrication method?

  1. #31
    Unregistered User Permit Roadsailing's Avatar
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    Gallium would be better than lead or Wood's metal, might be a bit expensive though.

  2. #32
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    Pure gallium shrinks as it solidifies, making it not suitable for this purpose. Wood's, Field's, and a few other low-temp alloys contain bismuth, partly to lower the melting point and partly to provide the benefit of expanding very slightly on solidification, for a short amount of time. For the low-melt alloy I have in the shop the sticker on the tub says expands 5% for the first 24hrs then shrinks 3 to 5% after complete precipitation (solid solution precipitation, too much metallurgy to try to explain in a short post.) By expanding slightly, the alloy keeps the tube filled and won't slip out of the straight tube, or displace and cause kinks or ripples in the steel tubing when bending.

    Other tips:

    -lightly oil the inside of the tube to help prevent rips and tears when using low-temp alloys to bend tubing with.
    -Don't use gallium based alloys with aluminum tube-it'll turn it to tissue paper if there's a scratch or nick in the tube wall.
    -Don't use a torch to melt out the alloy-you can cause it to liquefy in the middle and build up enough pressure to explode if the ends of the alloy bar don't melt to relieve the pressure.
    -Don't use a torch to melt the alloy ever, it has a low vapor pressure and even mild overheating can cause toxic metal vapors.

    For sand bending, you need to plug the ends of the tube and fill them with HOT sand-don't use it cold unless you pre-heat the tube with the sand in it prior to sealing the ends. Steam explosions, bad shit happens. And you need to plug both ends of the tube tight enough that the sand won't displace the plug-it needs to be packed firmly, but not rock solid, and it should not be allowed to squeeze out or you'll get kinks, ripples, and collapsed tube. Pack it too tightly, and the tube will just split when you go to bend it. Takes a practiced hand.

    If you're going to cut bends and weld them together, get one of the nifty cutting layout tools that's a flat plate with the bend profile cut out of it and the degree marks lined up on the inner and outer radii of the bend. I just got a stack of these and I wish I'd had these 10 years ago when I started...they make tube layout so much easier and so much more repeatable. I set mine up for band-saw usage on the vertical bandsaw by cutting through the plate so I could insert the band into the plate, slide it back into the degree marker cutout, insert the bend, cut the tube straight and square to the tangent, and it cuts my joint prep by half or more. So nice.

    Also, all mandrel bends I get here in the states are greased inside with what smells suspiciously like the Colonel's own recipe. If you don't clean out that grease, your header tubes smell like fried chicken or french fries, and you can get weld contamination or even fires going just from the hot grease.

    This post brought to you at 3AM by Mount Gay and Coca-Cola.
    Last edited by Xnke; 16-02-18 at 07:14 PM.

  3. #33
    free hugs! Paddington's Avatar
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    Also timely thread for me. Larger motor going into small hole, nothing off the shelf etc.

    I can buy stainless exhaust flanges from the UK no problem, but some of them look pretty rough, so I think I'd rather have my own made here in Melb.

    I also like TIG and I need to practice. Has anyone got some handy youtube vids of how people take a round stainless pipe and square the ends? Rover V8's have a very square/rectangular exhaust port.
    Quote Originally Posted by Stix Z
    i'm upset i lost that video of that aboriginal woman taking a dump on a train that was on youtube
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    Sorry, am late to this thread. I have been protesting against whitey oppressors all morning with my people. I shall serenade this thread with my didge until nash comes in and puts it all into perspective.

  4. #34
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    finigans garage recent video shows how he does round to square forming... basically hit it with a hammer. when I have done it I made a form out of solid and pressed a short section of round over it with a garage press.

  5. #35
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    Basically get some square stock, grind the corners into a suitable radius, and whap it with a hammer til it's close enough to tack in. Then heat and beat til it's correct.

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