Band saw blades are thin and prone to snapping during use. But you don’t have to run out and purchase a new saw blade every time this happens. Instead you can use an oxyacetylene torch and braze it back together. The area where the blade snapped that you repair is called the join. The join is made by heating soldering wire repeatedly and allowing it to cool, which is called an annealing pass.
Cut a groove out of the centre of the steel bar stock that is 0.035-inch deep by 7/16-inch wide to create a space under the blade to prevent the blade from being soldered to the fixture.
Use a power sander to grind down the broken ends of the blades, creating an angled bevel on one end and a matching bevel on the other broken end so that they fit when placed together.
Place flux onto both sides of the broken blade.
Insert the broken blade, matching up the broken end parts and putting them close together. Cut a piece of solder that is slightly larger than the lap, which is the area that needs to be soldered back together. Slide the piece of solder in between the broken pieces.
Light the oxyacetylene torch. Run the flame over the joint slowly until the solder melts. Once the solder begins to flow, remove the flame. Let the joint cool. Re-heat the joint until the solder melts again and slowly remove the flame so that the joint cools slowly. Repeat this three more times, turning the flame down to a lower heat each time so that the blade cools down at a slow pace. This is done so that the joint you make is strong and won’t snap on you.
Let the blade cool down completely. Remove the excess flux and solder with a file until it is ground down to the thickness of the soldered joint to match the rest of the blade.