Tom Porter's Recumbent Bike Plans - SWB versions
Tom Porter's Recumbent Bike Homebuilder Plans

Welding and Brazing Steel
The steel I use on these projects is joined by both methods, though the welding I use only to join the main tube miter cuts. These cuts are then reinforced with what Iíll call a wrapping gusset that is brazed around the welded miter. Brazing is easier than welding but requires more cleanup but I seem to remember some types of flux reduce this considerably. Custom frame builders contend that fillet brazing is stronger because of the lack of metal crystallization.

Welding/brazing requires gas and oxygen to really be efficient. Acetylene burns at a slightly hotter temperature than MAPP, but MAPP is a denser gas. I myself use MAPP/oxygen and have built 12+ frames with same cylinder of gas. The tank size I use is called medium. Easily portable setups come in small and medium tank sizes. MAPP is more difficult to weld with but can be done.

The welding torch I use is a Victor J 100 C. This allows one to use a smaller tip than the general run of the mill that everyone uses. The tips I use are the OO, this tip gives a small heat affected zone allowing the brass to flow in a small fillet giving a TIG like appearance and makes it more difficult to blow holes in the metal ( a common problem of too big a tip). For a small wall thickness as .035 or .028, I also use a heating tip (has six holes) for the heating of metal for forming. The whole setup of torch and tanks weighs about 80 pounds. The bad news is this will cost about 400+ USD. The good news is a TIG rig will cost 1700+ USD. A cutting torch will be used on any of these builds.

As an aside I did use a cheap torch setup for a project ten years I purchased at a home improvement center that used small cylinders of MAPP and oxygen. Tip is small enough for brazing (I donít know about welding) thin wall tubing. The trouble stems from when you have to preheat the bottom bracket shell and dropouts as this type of torch uses ghastly amounts of the oxygen cylinders at 7 USD a bottle, I then borrowed (for 4 years) a friends dormant setup till I finally purchased my present setup. 

If you would like obtain much more information on all aspects regarding bicycle framebuilding I would recommend the frame builders discussion area at www.bikelist.org/framebuilders, this is a very intense internet group with input by many people with much experience dealing with almost any process involved with bicycle frame building. Do this especially if your metal joining experience is rather limited.

The major beef with brazing concerns cleaning off of the joint area of flux and scale afterwards. There are a couple of solutions that I will be trying as I go along. The first is using a rag soaked with cold water that is applied to the area immediately after youíre finished brazing the joint and a product called flux remover that is available at aaccobraze.com which is located in Butler, WI. This is in the Milwaukee metro area about an hour from where I live, so I will probably have some more to add to this discussion about this problem later on.

Filler rods I use are 1/16Ē 4130 for the steel welding, a very small amount of this is used, and brass for brazing. Standard brass is rated at 60K tensile strength and has always been adequate for me. Flux is used to clean the metal for brazing and comes in several forms, I use the coated 1/16Ē stuff but Iíll have to look into other forms that seem to make for less of a mess. A pound of brazing rod will last a long time for bike building.

If you donít know how to weld/braze, take classes at your local technical school, I learned all forms of welding this way years ago. Alternatively you could press gang a friend or as a last resort pay (gasp) someone to do it for you. It is quite simple to learn how to gas weld.

More esoteric detail about the processes will be given/illustrated during the progress of building.

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