I finished welding the front triangle and chainstays of frame #6 on Labor Day Monday. Still not where I want to be in terms of consistency in puddle size of the welds, but i didn’t burn a hole in any tubes which is a good thing. My miters were pretty tight this frame. Really good miters = better welds! I think that’s something everyone that TIG’s already knows but…if you spend more time on getting your miters solid with as little a gap between tubes as possible, you’ll spend less time welding and doing any cold-setting of the frame because it’ll be good after the 1st pass.
The PMW headtube is great to weld, not sure exactly why, maybe because it’s just so thick that it’s pretty difficult to mess up unless it’s on one of the other tubes that join it. Even with the thick headtube, you can see that i was getting good penetration, maybe too much. I don’t have a head tube heat sink but I doubt there’s much distortion. It’s 5mm thicker at the ends of the tube so that probably keeps it nice and round!
I have been getting some weird colors on the margins of the beads on some joints on all my frames, less on this frame but it’s still happening. The purples and blue’s don’t worry me but the black at the edge of the bead does (look on the upper part of the head tube/top tube junction. It looks like a shadow or that i undercut the tube but it’s not either of those). I clean the hell out of each tube with Simple Green, water, emery cloth, wire-wheel, and even wipe it down with some solvent before welding. I backpurge the frame with argon at 4cfh, use 18cfh postflow on the torch for 10 seconds…and it still happens! If there are any TIG welders out there reading, any comments would be greatly appreciated!
Next step is adding the seat stays. I’m trying to figure how to bend 19mm tubing (0.9mm wall thickness) so I can create a new style of wishbone seat stay…but the $24 conduit bender I got at Ace ain’t cutting it. The tube is just folding where it should be bending.