Making a motorcycle chassis or this is what tools are for.

[KustomsbyKent]

Steveofthenw,
As Tony explains in his document, brazing has some advantages for fatigue and vibration dampening, as well as not taking so much heat into the tube.
While it isn't as strong as a steel filler metal would be for Oxy-Acet or TIG welding, the weld bead can be larger which helps add additional material to make up for the lower strength, and because it is a lower temperature there is less chance of burning through the thin-wall tubing and lessening distortion, which is pretty critical on a racing bike.

If you have a torch, pick up some flux coated brazing rod and give it a try... it is more like soldering than welding though as you tend to heat the filler metal and puddle it on rather than making a puddle on the base material and dipping into the puddle.
You can use Oxy Acetylene or Oxy Propane or the electric arc on the TIG welder.
Plus, Brazing is just fun welding as well!
Altho I just like welding... especially Tig, and Brazing, and MIG and stick. Not so much on flux core because of all the spatter.

Thanks to Tony for posting that nice write-up, quite helpful for anyone building a frame and would like to minimize distortion and maintain accuracy. Lots of good building practices and helpful tips and tricks.

For tube notching, I prefer to use my abrasive tube notcher, and second choice would be the end milling operation. Hole saws are my last choice... rough cut and hard to creep up on the fit. I have used hole saws on large tubes for fitting 2x3 square up to 2" round with 1/4" wall thickness.