Originally posted by scottm
I missed this thread, its funny how close it came to the FFA.
nitroking, good luck with the project. I am a certified welder myself, so heres what I recommend. Do a lot of practicing before you weld your trike. Tig and mig are your best choices, and each has its advantages/disadvantages. A vehicle frame is subject to flexing and dynamic impacts that lead to cracks, so the quality requirements are much higher than a fence or a table. Don't take any chances. If the weld looks bad it probably is.
Always make your tube joints fit as tight as possible to minimize gaps for good welds. Tools that fishmouth the tubing, called coping, are expensive, but give the best results. You can do it by hand with grinders, but it is tedious - dont get lazy, do it right.
Rectangular and square tubing is generally easier to work with, but round tubing looks better when it is finished, and comes in better grades. But speaking of better grades, avoid chro-moly tubing (4130 and 4140) for your first project, stick with mild steel, 1018 or 1020. There is too much to explain now, other than chro-mo will crack easily if it is not preheated before welding and normalized or stress-relieved after welding.
I personally would weld it with tig and a ductile filler, like ER70-S2 or ER70-S7. You can get good results with a stick welder, but it is much harder. For stick, 7018 and 7024 make beutiful welds, but are more difficult to use on thin parts and in tight areas. Try 6013 and cut the rod in half for more control.
Good luck and post some pics. Me and zandor can probably help you as you go.
Oh, and be sure to make a killer r/c track out there on that land!
