Types of Schwinn frame construction

[Miq]

This one applied for in 39 introduced the new welding technique:

I think he wished it would "leave little or no flash".

 

[SirMike1983]

"Butt flash welding" sounds more like when you sit down on a vinyl car seat on a hot day.

 

[AS-1]

Thanks, @AS-1 the Electro Forged terminology was used back in the late 1950's to my memory. I would bet it was something Schwinn developed during their war product production period.

John

I think the technology for joining two halves of a pipe elbow has been around for a while. The war effort advanced spot welding, stitch welding and rod (electrode) welding a long way. In other words, welding together of mirror images (pairs) was not specific to either the bicycle industry generally or Schwinn specifically. Is that a fair statement?

 

[Schwinn Sales West]

This one applied for in 39 introduced the new welding technique:
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I think he wished it would "leave little or no flash".

I do not know of any Schwinn models that used frames that were built with a (separate) sleeve inside the tube as described in this patent application. The Electro Forged welding was never used on "Butted Tubing" or "Swaged Tubing", only thicker walled straight gauge tubing. The Electro Forged welding technique did not use a "V" out welding area which was "filled in with a filler rod" by going around the tube (as shown in Figure 5. Electro Forge was a nothing more than a glorified big spot weld, all done in one charge of electricity. Remember, this was intended to be a high-volume production process on a low price point unit. No clean-up, or minimal weld clean-up was the goal.

I believe you will find hundreds of different patent applications from the late 1800's to the mid 1950's bicycle inventors. The idea was to cover every possible way to build something with a patent or even just a patent application/pending. It was like money in the bank that you could sell, trade, or barter with other companies that wanted or needed to use some part of the patent you owned. It was just business and covering your bases.

John

 

[Schwinn Sales West]

How about pics of the bikes built with the different techniques?

@GTs58 please correct me and add in details I'm missing here. Electro-forging (EF) started in the lightweights on the dropouts prewar (1940). During the wartime the bottom bracket EF started. Not every joint, but slowly more and more over time. The first New World on our list with an EF bottom bracket was an I serial early wartime bike in bright green. By the end of the I serials many of the joints were EF. Here are some EF pics:
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@GTs58 got more pic examples of the stays EF joints?

Thanks @Miq for adding the photos to this thread, it really helps to show the different processes I have tried to explain in words.

I have actual Schwinn plastic Uni-Lug slugs that were used to make the ceramic molds for the steel lug casting process. I do not have the ability to post photos, but is should be included with this thread to help everyone understand how things were built.

John

 

[Schwinn Sales West]

This patent applied for in 41 shows Frank trying to protect ideas related to using EF as a mass production method. This patent is for a tool to clean the flash off of the outisde of an EF tube joint. Frank usues the term "butt flash welding" which is not nearly as futuristic as Electro-forging.
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And by 1943, it was still called Butt Welding in an industrial application, not Electro Forging.

Somebody at Schwinn, likely in the marketing/product management/advertising area spun Butt Welding, into sexy Electro Forged welding. Hey, they got a good run out of it, 75 years later we are still discussing it. LOL

John

 

[Miq]

Making the patent as broad as possible is always the goal. The reason I posted the ones above was to show the timing for when Schwinn started using the electro-forging process and the fact that they invested in protecting the ideas they were generating while using it.

I am really interested to see the Uni-Lug bikes. What models and years would that be found on?

 

[Schwinn Sales West]

Making the patent as broad as possible is always the goal. The reason I posted the ones above was to show the timing for when Schwinn started using the electro-forging process and the fact that they invested in protecting the ideas they were generating while using it.

I am really interested to see the Uni-Lug bikes. What models and years would that be found on?

You have been looking at them for 30 plus years.

All of the Greenville assembled bikes (except the welded aluminum framed numbered 564, etc models) used frames built with the Uni-Lug process. The cast lugs were the head tube (one piece), the seat lug, and the bottom bracket. They made different frame sized head lugs.

Note, Uni-Lug is my coined term, it was not a Schwinn term. To my knowledge Schwinn did not advertise or promote the process. I do not believe you will find much Schwinn literature promoting it. They wanted the lug frames to be accepted as "just another lug frame". Schwinn was trying hard to shed their "heavy bike" image and be more than your father's Oldsmobile.

John

 

[AS-1]

 

[cyclingday]

The Cleveland Welding Company pioneered the Electro Forging process in 1938.