Hi, I'm about to embark on building a swb recumbent and need a bit of advice. Will 2 inch diameter, 0.049 wall thickness 4130 cromo suffice? Will I need to post heat treat the frame? Can I weld other "normal" steel components onto the cromo frame such as rear forks, head set ect or am I restricted to cromo components?
2" cromo is acceptable. I dought you'd need to heat treat the finished frame. Welding steel to cromo can be done quite easily. The only problem is if you don't own a proper welding machine. ARC will just burn holes (in the cromo) unless you buy the smallest diameter electrodes possible (1.6mm?), coupled with low amps. Not good for penertration IMO. If you own a MIG or a oxy-acetelene device then you're cooking with gas .
I have been useing 1.75 x .062 Cro Mo tubing and 1.625 x .062 will fit inside with a little trimming for adjustable booms etc. I use oxy-acetelene to braze the parts togethter and have not had a weld fail in 10years. Just remember that keep the weld areas clean clean clean and it will go together real nice. Here's my bent building page www.bobmccutcheon.com. Keep us posted on your progress.