Welders of high production frames usually weld only 1/3 or so of two to three joints on a frame and the frame "tumbles" from bench to bench. They usually use a amperage pulser or a cold wire feed unit and fully robotic frame welding machines are also used (though more costly than kidnapped children) It's really the same as modern production lug work as it's an employee learning a simple part of a complicated process. Pretty much like any other type production (white or blue collar) job. There was a time when lugged frames were being built at a rate comparable to modern TIG production frame output and with the same care and artistic consideration (something between sporadic and none) though somehow the years have transformed them to art. ( ask me, I have several examples)

I make custom aluminum frames quite a bit. I also design and fabricate ALL the pieces of the frame except the cable stops. I also draw the tubes to the desired shape as well as bend/form the chainstays and do the stay end work. I design and make all the fixtures for manufacturing/welding/inspection/heat treating and final assembly. I don't usually work from a kit (there are exceptions) of any type and every single materials thickness, fastener shape and diameter is also my decision. I design my own cutters and weld my saw blades. There is nothing automatic about my welding process. The metal is applied to the joint with a filler rod just like fillet brazing (bronze welding?) and I control the amperage of a 10,000 degree arc held between my finger tips. I have worked with welding machine designers to improve the species as well as metallurgists and tube designers to provide a welders input. I have hundreds of variables to control while welding. and another dozen on the control panel. I contour the shape of my welding current (as one would view on oscilloscope) to meet my needs. I also mix my inert shielding gasses as needed. I have filed a few welds and with the filler being the same color as the base material on aluminum, requires far more skill than finishing brass on steel. Brass is soft,steel is much harder as well.

When "real" frame builders come for a visit they remove their hat and it stays in hand until they walk out the door.

I didn't write this to insult other craftsmen or methods, I just thought folks might like some insight to a process at this point far more rare than traditional frame building. I am looking forward to building a lugged frame at some point when I calm down (LOL)

I don't want to shock anyone with ghastly images so here is a link.
http://www.flickr.com/photos/frankth...n/photostream/