Originally Posted by
FBinNY
You're mixing terms with different meanings.
Butt weld refers to the type of the joint, namely 2 members meeting end to end, or at an angle with no overlap or reinforcement save the weld itself.
TiG welding refers to the welding process itself, which uses an inert gas to protect the weld area from harmful exposure to the surrounding air.
Whether TiG welded or not, most modern welded frames are butt welded
Yes, but TIG welding involves filler rod (for structural use). The Schwinn electro-forged process used resistance welding with no filler. You can do TIG welding with no filler, but it is generally not used for structural welds. I have not heard of any TIG welded bikes with no filler rod used for the joints.
You are correct on the nomenclature, a butt weld is a geometry, but the electro-forged process is not the same as most other welding techniques. It is more akin to spot welding, in that it did not use filler material and it was a resistance weld.
As far as I can tell, the techniques used in mass produced metal bicycle frames were thus:
Fillet brazed
silver brazed with lugs
Tig welding
Schwinn's Electro-forged
Adhesive bonding with lugs
And I'm not sure of MIG welding, but I wouldn't be surprised if it is used in the mass production of consumer aluminum frames today.