Help please with Durafix rods which dont work

  1. Bill Wrench New Member

    Messages:
    3
    Location:
    Devon
    I have purchased the Durafix weld rods. I am trying to weld alloy one inch wide and 3MM thick. I am using a burner which burns at 1933 degrees heat and the rods will not melt as shown on Facebook and you tube. I have followed the instructions and watched videos on you tube. They simply will not melt and flow. Does anyone know why please?
     
  2. brightspark

    brightspark Member

    Messages:
    28,884
    Location:
    yarm
    it must be not sufficient heat as aluminium is a good conductor it will dissipate easily. can you pack round the metal with with fire bricks or broken thermalite blocks to retain the heat. ive used the rods with no problems on small stuff
     
  3. CompoSimmonite Member

    Messages:
    4,365
    Location:
    Werrington, Stoke-on-Trent
    I've struggled with them as well. When I eventually got the aluminium hot enough for the rods to melt the plate being repaired distorted.
    There again I successfully repaired a small complete casting by pre heating it in the domestic oven first.
     
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  4. Bill Wrench New Member

    Messages:
    3
    Location:
    Devon
    The brochure states the rods melt at 732F but they don’t when using two and half times that heat. Thanks for your reply.
     
  5. Bill Wrench New Member

    Messages:
    3
    Location:
    Devon
    Thanks for your reply. They might work on a coke tin because it’s paper thin, but any thicker and it’s total failure.
     
  6. Brad93

    Brad93 M J B Engineering

    Messages:
    7,389
    Location:
    Essex
    Never had any luck with those type of zinc rich rods.
    It’s always been last attempt repair.

    Tig is a much better option.
     
  7. gordon stephenson

    gordon stephenson Forum Supporter

    Messages:
    6,652
    Location:
    Skelton in Cleveland U.K.
    I have always had a very good success rate with Durafix/Lumiweld type rods, As we know, the rods are melted by the heat in the metal itself, Despite what temperature the flame is supposed to produce, the metal must be hot enough to melt the rods, Have you done any practicing on scrap ally, of around the same size as your work-piece, Practice is essential to making a good job.
     
  8. Hopefuldave Intergalactic pot-mender

    Messages:
    1,425
    Location:
    The Shed of Danger, surrey, England
    I've had success with 'em too, things like the banjo-bolt union bosses on radiators, oil coolers, as above you do need to get the work clean then HOT and then break the oxide layer with a stainless tool (brush, scraper, etc.) so the rod can lower the ally melting point. I've used torches from the clip-on-a-disposable-butane-can to a Bullfinch, depending on the work. Preheating as suggested by Compo~ helps.

    Dave H. (the other one)
     
  9. no idea Member

    Messages:
    139
    I've found you need to "start" a reaction by scratching the heated aluminium then bringing the rod into contact with that area first. My understanding was that the rod melted when it was hot enough and in direct contact with the actual aluminium, rather than the oxide layer. They used to include a stainless steel skewer or brush in the kits but I've resorted to using a screwdriver to scratch the aluminium.
     
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  10. RonA

    RonA specialist in repairing sealed for life equipment

    Messages:
    1,500
    Location:
    Stockton on Tees, UK
    I successfully repaired my oil filler horn on my 1930’s car using those rods. The casting is approx 3mm thick ( Mazak I think, it wouldn’t Tig weld) & I used a plumbing heating torch. You do need to clean off the oxide film with the stainless steel brush & I had to wait till it got good & hot to make a make a good joint.
    RonA
     
  11. gordon stephenson

    gordon stephenson Forum Supporter

    Messages:
    6,652
    Location:
    Skelton in Cleveland U.K.
    The oxide scratch rods that I got with the Lumiweld that I bought was just a 250mm length of stainless tig rod, Worked fine,
     
    RonA likes this.
  12. Browser Happiness is an even fillet.

    Messages:
    579
    Location:
    South Lincs, UK.
    Sorry for being late to this conversation, but this morning I had occasion to use one of the Techno Weld kits I bought many many moons ago from Machine Mart. I needed a combined mudguard bridge and speedo sensor bracket for the front of a new bike I've got, and as I can't yet mould carbon fibre, ali seemed the next best thing. I realised after I'd spent quite a while laboriously hand-filing the bracket shape out that if I'd left a little more metal in place I could have simply bent the speedo bracket part to suit rather than having to solder/weld on a piece, but there we go!
    The bracket was made from 3mm ali and I had a try on a test piece first before potentially ruining the real thing. I found that:
    1. You really need an insulator between the workpiece and vice (if you're using one) as the ali happily conducts most of the heat away to said vice meaning heating takes for ever! A plumbers heat-resistant mat works very well, Wickes sell them as do many others.
    2. Holding the pieces together (mine was a tee-joint) is a pain in the jacksie par excellence! I used a mole-grip-type welding clamp and it marked the workpiece.
    3. All the heating anneals the bejeezuz out of the workpiece, and when I say annealed I mean that it's now softer than a blancmange wrapped in a duvet! I had a look at how to re-harden but it seems to involve either beting it with a hammer to re-work harden (not desirable as I'd spent ages polishing it) or a chemical process with cyanide or something else equally charming. I am hoping it will be OK as-is but can see that being this soft could cause problems for other projects depending on what you're making.
    4. It does you well to practice. It takes a while to get your co-ordination and order of doing things sorted, as well as achieving a neat finish.
    If I can cudgel my brain tomorrow I'll take some pics of the finished bit, which has now been painted prior to fitting but you'll still be able to see the results.
    I'd use it again but would do myself well to practice some different joints, and would like to find some better ways of jigging the parts together.
     
    slim_boy_fat likes this.
  13. slim_boy_fat

    slim_boy_fat Forum Supporter

    It's tomorrow, today. :whistle: :D
     
  14. Browser Happiness is an even fillet.

    Messages:
    579
    Location:
    South Lincs, UK.
  15. Hopefuldave Intergalactic pot-mender

    Messages:
    1,425
    Location:
    The Shed of Danger, surrey, England
    Look good, what bike are they going onto?

    Dave H. (the other one)
     
  16. Pigeon_Droppings2 Member

    Messages:
    2,424
    Location:
    london
    Have always worked fine for me....I use mapp gas...and if it's a big part I insulate the part so it heats up.

    Repaired a water pump housing with them...used a steel former and still going well to this day.

    The part needs good heat...and the oxide layer needs to be broken for it to work.
     
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  17. Seadog

    Seadog Forum Supporter

    Messages:
    5,658
    Location:
    NE London - UK
    Insulate well, get it hot then brush it with a clean stainless steel brush and proceed
     
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  18. hermetic

    hermetic Member

    Messages:
    104
    Yorkshire UK
    Is there any branded paperwork or packaging that came with your rods? if they are not melting at the advertised temperature I would say they are ordinary alloy tig rods, and it is either a mistake, or a con. I have used Eutectic branded alloy welding rods and powder flux for welding alliy sheet in the 1970's but I was using O/A for a heat source, and it was easier than brazing, actually more like soldering, so I would say it is either not enough heat, or they are the wrong rods.
    Phil
     
  19. Browser Happiness is an even fillet.

    Messages:
    579
    Location:
    South Lincs, UK.
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  20. dannyp Member

    i decided i dont like zinc rods, they ether work or they dont never found any middel ground with them unfortunatly they dont work often enough for me
     
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