Originally Posted by HMBAtrail

The term "expensive" is a relative term. For some, a 1986 Honda Civic is a treasure. For others a 2 year old Porsche is pedestrian. If you find value in the process then it isn't expensive, if you don't then it is. If you just want a bike frame, then go buy one and problem solved. if you want to learn as you go, then you should be willing to pay for that experience.

Go to Aircraft Spruce and order online. Order some 1", 1 1/8" and 1 1/4" 4130 tubing in .035" thickness. You can buy it by the foot. By a lot of it.

Buy cheap practice lugs. I have a box of them that I will send you for free if you pay the shipping. Braze up 30+ lugs to short sections of the 4130. After you braze up each joint, cut it in half and see how much penetration you are getting. Don't take short cuts, don't depreciate the value of the process. Remember, that is where the value is. If you just find value in the end process (i.e. the frame) then you are wasting your time. Learn as you go. It is the only reason to do this. An even cheaper alternative is to order some .058" walled 4130 in the next size up from Aircraft Spruce. .058" in 1 1/4" O.D., for example, will slide over 1 1/8" tubing. You can use the .058" as a sleeve and then braze it up. It is a very cheap route to learn torch control and capillary action of the filler material.

You can buy silver or bronze filler material. Silver is a bit easier to use but bronze is much cheaper. Dealer's choice on which direction you want to go. Buy 1/16" diameter rod.

Use the black flux from Harris (you can get it at any welding supply store). Technically it is for bronze brazing but use it on silver when you are starting out. If you are just learning how to braze the longer effective zone of the flux will help you out and keep you charring the f*ck out of what you are doing.

If you are starting out without anything, the most expensive portion of the process will be a good torch, regulators and the tanks. Some welding supply shops will lease you tanks. Other places make you purchase the tanks outright with the assurance they will buy them back from you later on if you want to sell. The torches and regs can be bought from your welding supply store or online. But, if you don't know what you want then you can end up spending more online versus just going into the shop and asking for help.

Again, I stress that you use cheap 4130 straight wall tubing and old pressed lugs. You should NOT strike out and start building a bike from the get go. Learn to braze, learn torch control, learn the basics. Once you have that, then start putting it all together. Don't start thinking about how cool the bike will be because most likely it will ride like a bag of wrenches. Don't worry about that. Learn what you did wrong and improve. Don't start thinking about using stainless steel anytime soon. It is much harder to sweat and much easier to f*ck up. Don't start thinking about how you want to start lug carving and making it pretty and fancy. Do that after you learn the basics. You aren't building a Porsche. You are striving for that 1986 Honda Civic.

These are of course just my opinions and I reserve the right to be wrong.