Pros, Cons, and Practical Reality of using bandsaw blade welder? - Page 2
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  1. #21
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    I've been welding 1/2" bimetal blades in my standalone welder for years without issue.
    The key is proper annealing after welding and tempering after grinding.

  2. #22
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    A little thing I like to add...

    I have been trying to weld bimetal blades with an oxyacetylene torch. I practiced on a broken blade that I've cut into sections.

    One problem I have with standard torch is that the metal is so thin, that it's very easy to burn through. But here's what I learned in the practice:

    Use a very reducing flame. Meaning you want the outer cone (the feather) to be as long as you can make it before the flame turns from blue to bright white. I don't know why but using a neutral flame is a disaster as the blade stock will burn through as soon as a weld puddle forms. Using a strongly reducing flame gives you significantly more time for a weld puddle to form and not burn through the metal. It seems this works well regardless of the type of steel you are trying to weld, as in it works for mild steel as well.

    Use as small of a torch as you can to get the job done. I found a standard torch even with the smallest tip is still too large and heated up too big of an area. I bought a Chinese copy of Smith's The Little Torch and it does the job much better because you can have a small but very hot flame to heat the area that needs heat and nowhere else. #2 tip worked the best for 1/4" stocks. Using the small torch also meant you have much better maneuverability compared to a full sized torch, so I can weld larger projects too.

    Anneal must be done because when the blade, particularly bimetal is heated enough to weld, it becomes more brittle than potato chips. I've done an experiment on various parts of the waste blade, heated it enough to form a weld puddle and then try to anneal it. What worked is to hold the torch very close to the work, heat it until it almost melts, count to 2, then take the torch away, count 1, then back to the metal, count 2, and move the torch an inch away from the object, and repeat, moving the torch an inch away each time. The idea is heat the blade until it's bright red, then moving the torch so that the metal is cooling slowly, and to prolong its cooling time. After you get it so that your weld goggle is seeing the metal barely glow, remove the weld goggle and continue cooling the metal, and at this point with a shade of 3 a barely glowing metal will glow bright angry red without any goggle. Keep this up until it's barely glowing and keep at it past the point the metal isn't glowing anymore. Then keep moving the torch around, 2 second on, 1 second off, and you'll still see flakes on the metal glow from the torch touching it. Slowly back the torch away and let it cool naturally. When I did it this way the blade stock wouldn't snap cleanly when bent, but would bend as though it was soft wire. I do not know if hardening is necessary to restore the spring-ness of the original blade stock.

    But using The Little Torch I can butt the blade together and fusion weld it in 2 seconds but you need to take at least a minute to anneal it or else the blade will snap.

  3. #23
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    I just finished a complete restoration of a DoAll 1612 contour saw along with the original DBW 1A welder. The saw was built in 1968. It now works like a new saw. I think "MUD" is correct, the key to good butt welds is the annealing. In the case of Bimetal blades, you should anneal right after welding before removing the blade and then again after grinding the weld.

  4. #24
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    A trick I learned. At the right annealing temperature the blade is no longer magnetic. Use a small bar magnet and stop heating when it won’t stick.

  5. #25
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    You know I never heard anyone stick welding bandsaw blades together... anyone tried that?


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