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  1. #1

    Default Swap-meet aluminum "brazing" rod

    You've all seen the guy with the booth at the local swapmeet, demonstrating one or other brand of low-temp pre-fluxed aluminum and/or pot-metal "repair" rod that's applied via an air/propane torch. Often the demonstrator uses aluminum soda cans, since the nearly pure aluminum in them "tins" easily. A couple of times I have bought the minimum number of rods, and found that whether with a propane torch or with oxy-acetylene at very low pressures, these rods do work well on the soda cans but seem not to do so well on other aluminum alloys. Maybe I just haven't found the good combination.

    Does anyone here work regularly, even professionally, with low-temp aluminum rod? I'd like to find a rod, and a technique, that "tins" well (given well-cleaned base metal, of course) and will draw itself well into crevices (say .003-.008") by capillary action as with ordinary bronze welding on steel. As to your specific favorite brand of rod, I want it for aluminum, not pot-metal, which I expect might call for a rod with a lot more zinc. If this brand is not pre-fluxed, or even if it is, whose flux do you like? Do you pre-flux, or even pre-tin the pieces where you want the filler to draw itself in? Also, while I don't currently own an air-acetylene torch, I could get one if that's the way to go. Or I suppose I could get a little bottle of hydrogen, if you prefer oxy-hydrogen, as the old-timers did for gas-WELDING aluminum.

    (If it's not fully clear, I'm NOT asking about gas-WELDING aluminum, but the low-temp process, . . . although, just as a comment, for anybody who has tried gas-WELDING aluminum in school years ago, you might not know that you now can get gas-welding rod that is pre-fluxed!! With all of the cleaning and prep that aluminum requires, I thought it was a drag to also have to clean the ROD, heat it up, and tediously brush on the flux (which you had to mix with water) and wait for it to dry. The pre-fluxed rod is great!)
    Last edited by old jupiter; 03-01-2015 at 10:49 AM.

  2. #2
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    Default

    Like THIS or THIS?

    All you need is a hand held propane type torch for small pieces.

    Produces a sound joint that is stronger than the parent metal.

    No fluxes are required.

    There are no fumes.

    Low 732°F. working temperature.

    Joins thin or thick parts.

  3. #3
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    May 2013
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    Cantonment, FL
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    Default

    Both those products look to be great!

  4. #4
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    Quote Originally Posted by mbramble View Post
    Both those products look to be great!
    Do not know about a specific brand BUT.....

    I sure have had to grind a bunch of that stuff out of aluminum parts that had been repaired with that lo temp aluminum rod and failed soon thereafter..

    You cannot TIG after that zinc bearing stuff without grinding it completely out to clean aluminum with a carbide burr or mill....

    Am not a fan of that stuff... if something sounds too good to be true... well you know....

    Another problem with it is color match... those lo temp ones tend to turn black or dark grey over time...
    .

    *******************************************
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  5. #5
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    Quote Originally Posted by H80N View Post
    Do not know about a specific brand BUT.....

    I sure have had to grind a bunch of that stuff out of aluminum parts that had been repaired with that lo temp aluminum rod and failed soon thereafter..

    You cannot TIG after that zinc bearing stuff without grinding it completely out to clean aluminum with a carbide burr or mill....

    Am not a fan of that stuff... if something sounds too good to be true... well you know....

    Another problem with it is color match... those lo temp ones tend to turn black or dark grey over time...
    I guess I was thinking of the cast aluminum or pot metal type applications for this stuff, we've all at one time or another tried to TIG this stuff and it just doesn't work...this is the company I was originally trying to find, maybe it's the same rod

  6. #6
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    Quote Originally Posted by Ltbadd View Post
    I guess I was thinking of the cast aluminum or pot metal type applications for this stuff, we've all at one time or another tried to TIG this stuff and it just doesn't work...this is the company I was originally trying to find, maybe it's the same rod
    I could see using it on diecast Zinc/Potmetal/Zamak trim like old car door handle repair before re-plating...

    but for my money it is death on aluminum...
    Last edited by H80N; 03-01-2015 at 06:17 PM.
    .

    *******************************************
    The more you know, The better you know, How little you know

    “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

    Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

    My Blue Stuff:
    Dynasty 350DX Tigrunner
    Dynasty 200DX
    Millermatic 350P w/25ft Alumapro & 30A
    Millermatic 200

    TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

  7. #7
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    Apr 2009
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    Oswego IL
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    Quote Originally Posted by H80N View Post
    I could see using it on diecast Zinc/Potmetal/Zamak trim like old car door handle repair before re-plating...

    but for my money it is death on aluminum...
    Ah your just mad you bought a dynasty when all you needed was a propane torch! Actually have used a product called alum-alloy, on a very thin rivoted aluminum boat, and it did work. However i would consider it a heat on glue, but in some repairs, it does what it is needed. Basically we used it to build up the edges where the rocks scraped it thin.
    Kevin
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  8. #8

    Default

    Thanks for your interest and comments. I looked at all the links.

    [QUOTE=H80N;328342] I sure have had to grind a bunch of that stuff out of aluminum parts that had been repaired with that lo temp aluminum rod and failed soon thereafter.. QUOTE]

    The problem with that is, was the guy who made the repair that you had to try to salvage a real welder who knows enough to clean and prep the part as you do for TIG, and who understands getting the stuff to "tin," and even knows he might have to re-do the thing as many times as needed to float out any crud that his cleanup missed? Or was he just a homeowner who bought some miracle rod at a swapmeet? I'm guessing it is mostly the novices who use this kind of rod. And novices who sell it; some of the of the salesmen actually claim that no pre-weld cleanup is necessary. If the maker of the rod encourages their salesmen to make that assertion, it sure would make me question their credibility.

    That's why I'm hoping to talk to a welder who uses some version of this rod on a regular basis . . . if there is such a person.
    Last edited by old jupiter; 03-02-2015 at 12:00 AM.

  9. #9
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    Quote Originally Posted by old jupiter View Post
    Thanks for your interest and comments. I looked at all the links.


    The problem with that is, was the guy who made the repair that you had to try to salvage a real welder who knows enough to clean and prep the part as you do for TIG, and who understands getting the stuff to "tin," and even knows he might have to re-do the thing as many times as needed to float out any crud that his cleanup missed? Or was he just a homeowner who bought some miracle rod at a swapmeet? I'm guessing it is mostly the novices who use this kind of rod. And novices who sell it; some of the of the salesmen actually claim that no pre-weld cleanup is necessary. If the maker of the rod encourages their salesmen to make that assertion, it sure would make me question their credibility.

    That's why I'm hoping to talk to a welder who uses some version of this rod on a regular basis . . . if there is such a person.
    To be clear...

    I was not speaking of one or two poorly prepped examples... I was talking about DOZENS of them over the years .... many that appeared very well prepped... and failed within the soldered area...

    That stuff is a very poor metalurgical match to aluminum and in my opinion should never be used in a structural application... Zinc is brittle.. not so much Aluminum..
    Very different coefficients of expansion/contraction.... elasticity.. ductility...microcrystaline grain structure.. fatigue strength.. crack sensitivity.. etc..

    Cosmetic Applications...Repairing a diecast zinc headlight bezel on your 56 Oldsmobile...?? or granny's diecast Chatchki..??... YOU BET....
    But engine brackets... Cylinder heads.. etc...anything structural...
    AT Your Own Peril..!!!

    Go down to the LWS in your area and ask them... see what they tell you...
    if there are local users.. they would know..

    It does have some valid applications... HVAC folks use similar Solder to join Aluminum and Copper tubing..

    Why do you think they sell it at the Flea Market but not at the LWS..??

    Finding the proper filler for joining aluminum can be very complex and depends on MANY factors... there is no one size fits all...
    this selector chart and guide will help to illustrate that.. there is a dizzying array of possibles based on alloy and application..

    http://www.hobartbrothers.com/downlo...ler__eNttQ.pdf

    http://maxal.com/files/QuickSiteImag...g_9-12_doc.pdf

    This page should be helpful as well..

    http://www.hobartbrothers.com/produc...m-mig-tig.html


    Just my 2cents worth...
    Last edited by H80N; 03-02-2015 at 07:16 AM.
    .

    *******************************************
    The more you know, The better you know, How little you know

    “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

    Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

    My Blue Stuff:
    Dynasty 350DX Tigrunner
    Dynasty 200DX
    Millermatic 350P w/25ft Alumapro & 30A
    Millermatic 200

    TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

  10. #10

    Default

    [QUOTE].... many that appeared very well prepped... and failed within the soldered area... (end quote)

    Interesting. You say they (the well-prepped examples) failed within the soldered area; do you mean the deposited metal failed, or that the adhesion to the basemetal failed, or both? I ask because my intended use would be building-up and reshaping transfer ports inside methanol-fueled 2-stroke engines. Some tuners have a favorite epoxy product they use for this purpose; I was hoping the low-temp rod might be more trustworthy in it's adhesion (tensile strength not being too important here) (though the effect of exposure to methanol and its usual additives could be).

    (QUOTE) That stuff is a very poor metalurgical match to aluminum and in my opinion should never be used in a structural application... Zinc is brittle.. not so much Aluminum..
    Very different coefficients of expansion/contraction.... elasticity.. ductility...microcrystaline grain structure.. fatigue strength.. crack sensitivity.. etc.. (QUOTE]

    Right, and that's why in the initial post I asked if anyone knew of a good low-temp product intended particularly for aluminum, as opposed to the swapmeet rods that are zinc-rich. One of Ltbadd's links is to an outfit that swears their rod is a new-generation version "with seven expensive secret alloying elements instead of the usual three," and goes on to cite all of the big corporations that use it. Well, okay, . . . elsewhere they claim that while you should prep the weld site, remaining impurities have no effect. Mmm . . .

    I know that different aluminum alloys call for different TIG filler-metals for various purposes; in fact I'm currently trying to guess at what to load in my spool gun to try to save an "alloy-X" part. So I would not be surprised to be told that for a low-temp rod to tin properly it would have to be as alloy-specific as TIG rods are. That's why I started out expressing skepticism before asking if anybody had found any low-temp rod that's workable. You didn't rain on my parade, H80N, and I appreciate your taking time to tell me of your experiences.
    Last edited by old jupiter; 03-02-2015 at 10:36 AM.

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