Welding vs. Brazing

Smooth Transition

Originally uploaded by anthony.maietta

Last night saw the completion of Brianna’s fixed gear frame. I thought this photo highlighted someting quite well: the difference between welding and brazing. As you probably know by now my preferred method of tube joining is TIG welding the joints. You can also very successfully build a frame by brazing the joint together with brass fillets or with lugs and silver solder. In the latter two cases the tubes are held together with a secondary material (brass or silver) as a glue. The brazz or silver is heated above it’s melting temperature, and in an environment of flux, the brass or silver attaches to the tubes. Once everything is cool there is a joint, but the adjoining tubes/lug are still technically sperate piece of metal. They were never heated above their melting temperatures. Welding, however, does heat the tubes (or in the case of this picture the dropouts) above their melting temperatures right at the joint. These molten area meld together and fuse into one new continuous piece of metal. In the picture there were three pieces of steel all coming together: a chain stay, the dropout and the seat stay. You will notice that there is no transition line between the stays and dropout because during the welding all three became one piece of steel.

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