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  • cliffrod
    replied
    Here's a couple of pics, Bill. Close up of the semicircular failed weld and then larger pic pointing to location of this flawed welding attempt. It appears to be a clean gap, now wheeled/ planished into itself. This was within the area where I filled or welded up a 3/4" melted hole, so probably had some failure of flux or contamination that interfered with the repair integrity. If I can clean & flux it, It will probably melt back in ok- certainly not aviation-spec, but ok for this seat this time.

    As far as welding method, I've been doing things pretty much as you describe above. I set my pressures with a vacuum/pressure gauge, which helps a lot. The smallest tip I have is the one I use and it seems to work fine. I am adjusting the cone to expedite or slow tacking or welding progress & keeping things well brushed and clean from contamination. I haven't cleaned anything with alcohol, so will get some and use it. Contamination doesn't seem to be as much of an issue as managing heat & rate of weld, which I realize is a matter of practice if the method & prep is right..

    In part, this seat effort is practice for later welding of the gas tank.



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  • Bill Tromblay
    replied
    Hi,

    Pictures would help a bunch. Cracks are caused by excessive over heat or back cracking due thermal expansion and contraction. To weld up the cracks, wash off all the flux, clean with a wire brush, reflux and start fresh. No need to vee, do to the thin material thickness for penetration. It is sometimes needed to cut away ugly metal to expose good aluminum to reweld.

    Cleanleness is very important. You must wire brush off any oxide, then clean with alcohol or other cleaners. I even file the edge of the sheet to prevent contamination from the sheared edge. Be sure you are using bottle water in your flux with no steel brushes or steel other wise present, steel oxide will kill the flux, which causes crap welds. With Oxy/acetylene, pick your tip size and regulator pressure per the recommend charts. For tacking set the cone length to 3 times the material thickness, to weld set the cone length to 2 times the material thickness. By shortning the cone length, torch is at a lower temp and slows down the weld process. Always set a feather on your torch to prevent oxidation.

    hope it makes sense,

    Bill

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  • cliffrod
    started a topic Bubble gum, cracks & holes....s

    Bubble gum, cracks & holes....s

    instead of possibly burying this query in a project build thread, it deserves its own thread...

    I have gas welded the now less-than-063 thick aluminum seat pieces for my Guzzi build. Since its the first time I've done anything like this, I made this one from scrap I had on purpose- no idea what it actually is but It forms and welds easily without seeming prone to work hardening. Seems very comparable to the known 3003 H14 I've worked with. This seat and fender are intended to be practice pieces that will be used if they are successful or be used as patterns for the next pieces. There's a lot of fitting , cutting and development needed for this seat-fender-taillight assembly that I didn't think could be achieved without real parts in hand.

    Most of the weld is ok, not great but serviceable. After tacking, I tried to weld it in short lengths to limit the bigger holes. I have a couple of burned edges and interior holes that I've built back up with an ample amount of weld.... Not perfect welds but there's now more metal than hole. In these places, there are a couple of cracks that look more like areas of failed weld (probably contamination during the attempt to fix the holes) than cracks that have been created by working the welded area. I don't have any pics right now, but will get some shortly.

    Is it more practical to make/cut & install a larger patch or to try to open & clean the cracks? I expect trying to vee & clean the cracks will be a folly on material this thin. The goal is to be able to properly fix problems like this when I encounter them, even if this actual seat becomes wall art in the end.

    TIA, guys.
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