Yes I understand what used to be the norm, I brazed up my first 4130 frame back in the early 80's with Nickle bronze wire and Vapourflux. Gas welding using a wire filler was not ever an acceptable option and now 40 years later Industry best practise is to Tig weld. See if you can find a Company producing Club's made in the last 20 years that were 'Gas welded' or even brazed. Just because someone did it before doesn't mean it was the best option, Tig welding was the accepted best option in the 90's.4130 was invented for Oxy acetylene. Because someone tried to weld some tube with a torch that a dock worker would use is not quite apple to apple. There would be no Piper Cubs if you couldn’t weld with OA.
All true.I worked in the Racecar industry for many years and race cars haven't been brazed for many decades as its a much slower process than TIG welding and there is less control of the heating than with a TIG or MIG. Also the flux used also needs to be removed after Brazing even when using Vapourflux.
Gotta dispute this. 4130 and gas welding have been making strong durable airplane fuselages and assemblies for longer than just about all of the folks on this forum have been alive. Museums and airport hangars are loaded with airplanes built this way. An anecdote on one poorly done repair does not make the process unsuitable. There are benefits to both with the whole TIG vs OA argument covered well on the above mentioned threads...I'd also suggest that Oxy Acetelyne welding isn't the solution for 4130 tube thin wall welding. I've seen an aircraft frame repair that had to be cut out and replaced with new tubes due to the amount of heat used distorting the weld area.
Gotta dispute this too. Condition N IS Normalized tube, which is also about what happens when you gas weld an assembly. That is one of the beauties of 4130. Material strength is not changed by welding it.Also as far as normalizing after welding that Shouldn't be done in my opinion as the 4130 tube is supplied in a 'Condition N' and adding large amounts of heat will reduce the strength of the tubing.
We are not talking double butted tubes in bikes here. This is a forum on homebuilt airplane tube structures, and they are made of straight 4130 tubes. The load condition that usually ends up setting the tube sizes are resistance to buckling and crippling under compressive load, which is dominated not by yield strength but by cross section I times the elastic modulus of steel - a pretty much fixed number for all steels.BTW High end 'Steel' bike frames are generally brazed due to the very high tensile tubes used that have high Manganese levels.
A very close friend of mine,who passed away a few years ago,supplied Wag Aero with all of their cub frames and many components to the airframe.See if you can find a Company producing Club's made in the last 20 years that were 'Gas welded' or even brazed.