^^^^^^^
This
Why Was MAPP Gas Discontinued?
- Thread starter dr_clyde
- Start date
This
15 thou, that's thin for sure.
That's about 28 gauge.
Even with .023 solid wire and C25 gas, that's still thin for MIG. With the rule-of-thumb of 1 amp per thou metal thickness, that's only 15 amps of current.
Down that thin and that low of an amperage is more TIG IMNSHO.
Brazing? You still have to clean it to bright shiny metal, not rust and crud. Flux helps too, and also gives you the visual clue that when the flux liquifies you are usually at or close to the proper brazing temperature (with the proper flux that is
).
Oxy-acet tip size? Small.
Practice first. And don't get the oxy-acet flame 'tip' on or near the metal, you'll blow a hole right through in an instant. Lincoln/Harris chart suggests that you only need a size #0 23A90 tip for 1/64" thick metal, maybe go up to a #1 (suggested for 1/32" thick metal) and keep the flame slightly farther away. 1 psi on both oxygen and acetylene with those tip sizes. Did I mention to practice first? 
And brazing works best (in general) with tight-fitting joints where the filler flows in via capillary action into the ~2-5 thou gap. Your muffler has much bigger crack than that.
That's about 28 gauge.
Even with .023 solid wire and C25 gas, that's still thin for MIG. With the rule-of-thumb of 1 amp per thou metal thickness, that's only 15 amps of current.
Down that thin and that low of an amperage is more TIG IMNSHO.
Brazing? You still have to clean it to bright shiny metal, not rust and crud. Flux helps too, and also gives you the visual clue that when the flux liquifies you are usually at or close to the proper brazing temperature (with the proper flux that is
).Oxy-acet tip size? Small.
Practice first. And don't get the oxy-acet flame 'tip' on or near the metal, you'll blow a hole right through in an instant. Lincoln/Harris chart suggests that you only need a size #0 23A90 tip for 1/64" thick metal, maybe go up to a #1 (suggested for 1/32" thick metal) and keep the flame slightly farther away. 1 psi on both oxygen and acetylene with those tip sizes. Did I mention to practice first? And brazing works best (in general) with tight-fitting joints where the filler flows in via capillary action into the ~2-5 thou gap. Your muffler has much bigger crack than that.