I understand the basic difference between brazing (adhesion with the rod/flux) and welding (fusion with filler). I understand a brazing torch cannot cut metal like an O/A cutting torch or join thicker stock like an stick or 220v mig. But...
Given the most home and hobby metal joining is between thin sheet and thick stock, What I don't understand is why if brazing is strong enough for mountain bicycle brackets, etc; is versatile enough to join dissimilar metals; can be done with simpler equipment (air/fuel torch); and with lighter-duty safety equipment (shade #5 goggles vs. helmet), why then is all the chatter on the use groups about which
110v mig to buy for home shop welding?
What am I missing (as a Newbie here) in the faults, shortcomings, lack of capabilities of brazing with a decent torch and either acetylene/air or mapp/air? TIA
Brazing, if done right, is stronger than the base metal. So is high test silver solder. To answer your question, it's marketing and the search for the newest, fastest, bestest, etc. (kinda like computers)
Tig the BEST weld, but the most expensive and the slowest. Next slowest is ox/acy (but inexpensive). This has been used (developed) during WWII to build combat airplanes. Still is used a lot to build airplanes and race cars, and motorcycles, etc. A lot of dirt track cars are build using brazing rod also, to avoid over heating an area. Same reason it's used to fix body panels on cars. However, the newest cars have an alloy that gets annealed with heat. So, most body shops use a mig to avoid too much heat. (to avoid spreading heat to surrounding areas, the HAZ, or heat affected zone). Mig can look "good" on the surface, but not reach fusion or penetration. You need a bit of practice to tell the difference.
Mig is the fastest to do production work well. However, most battleships are built with stick arc because of it's ability to lay down huge rods on thick steel. And you don't need shielding gas. Plus, rod is convenient to buy, carry, and store.
Bottom line is they all have their place. To fuse, all methods must melt the base metal and add filler. Except for brazing (use a welding tip). To braze, you just need to heat the metal to it's "tinning" temp, around 1500*F or less. Soldering takes even less heat and looks the best (IMHO). Most joints are suitable for this except butt joints (not enough surface area) Although, I've brazed 3" pipe with a butt joint and couldn't break it apart. Your job is to determine which method is most suitable for YOUR project......
A 110 volt Mig machine is the closest thing to a metal hot glue gun that there is. If you get the flux type wire, you don't even need gas, just a plug. You don't need any skill at all to just blast things together (watch Junk Yard Wars for examples of that) - but at the same time Mig is the easiest method to do really bad welds that either look awful, or look good and ARE awful.
Brazing is probably more expensive, harder to learn how to do properly, requires skill and time in fitting of the pieces to be joined, needs better cleaning, and is a lot slower than Mig.
The only saving is in start-up cost. You can do a little brazing for about $50 or less for the Mapp torch setup and some brazing rods - but only a very little before you go broke buying those little bottles for about 30 minutes of flame time!
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