Wow, First let me say thanks for all of the interest and contributions in this thread. I had no idea how many of you have a dormant interest is this old "technical stuff".
Like I stated earlier, "For Better or Worse" Schwinn is best known for the millions of bicycles they built and sold using some form of the Electro Forged frame technology. Every kid in America either rode a Schwinn, or wanted to ride a Schwinn in the 1960's and 70's. I would guess that this decade also aligns when we Caber's were all kids out riding the wheels off of our bicycles, and the only parental guidance required was to be "home by dark". I personally think the "Schwinn" term Electro Forged is some advertising or marketing spin. When I think Forge, I see a Blacksmith pumping air into his fire and hammering out a new set of horseshoes. But it's hard to argue that the process and the term has been around for a good long time. I was surprised to see that the Captain Kangaroo and Schwinn was barely using the term in 1967. I have a quality Schwinn wall board from the 1970's and it makes no mention of the Electro Forged parts hanging on it. So, although Schwinn might have used Resistance/Butt Welding in the 1940's they surely did not use the term in marketing until much later. It was a technology that grew over time at Schwinn.
I think we are getting hung up on the wording and the technical welding differences and missing the bigger point. Schwinn needed a way to quickly build a high-quality frame "that had the looks" of the Filet Brazed frames they had built their reputation on for the past fifty years. The frame design had to use a method that lowered the labor cost to produce. Electrical Resistance welding was being refined and being adapted to production applications. But the Schwinn coined term Electro Forged was a bigger deal than "just a method to weld metal together". The electronic welding method was an important piece of the puzzle but saving production labor time and cutting costs to allow this technology to be used on lower price point models was the focus. It was designed to be used on bicycles that retailed for under $40. Mitering tubes at different angles and to fit different diameter tubing is an expensive step and requires skilled labor. Schwinn designed the "two piece/welded" head tube in a way that allowed the top and down tubes to be joined (Butt Welded with electronic resistance welding) by a straight Butt Joint. This eliminated the mitering step and indexing steps. Money saved when you're building a million frames every year.
If you look at the many frame examples made from the early 1940's all the way up to the close of the Chicago Factory in 1983 the Resistance Butt Weld frame construction changed and evolved. The early bikes had maybe two or three tubes joined by the Butt-Welding process, and by the 1970's almost every tube was electronically joined. For example, the Cantilever bars eventually were spot/resistance welded to the down tube and also at the seat tubes. The early Electro Forged frames might have only the seat tube, and head tube done by the resistance welding and the cantilever bars still done by hand with brazing (hidden under the tubes to save clean up time). Look at the changes in the pressed nipples on the early 1940's EF bottom bracket shells and compare them to the 1970's frames. The later parts place the welded joints further away from the stress points. It's still an EF type of design, but it was more refined. Schwinn had the best equipped metal Test Laboratory in the bicycle business, and it was "on site". They did their own Rockwell hardness tests on the bearing cups and cones they made. They built a machine that a bicycle frame would be bolt to and then put through pedal load cycles. If the frame broke, they went back to the design and made the necessary changes. It was very important "financially" to make frames that "Did Not Break" because Schwinn offered a Lifetime Replacement Guaranty. The Electro Forged frames, parts, and welding had to pass stringent testing before the design was released into a new model.
The Bottom Bracket shells, the head tubes, and the fork ends were all parts that had to be designed and specially made to work with the new resistance welding process. So, just my opinion, but when we say Electro Forged, we are talking about a frame system that had custom designed parts made specifically to work in concert with the new welding process.
Thanks again, John
