Vertigo Cycles
Well-known member
Hello Gregor,
As always, thank you for posting and sharing. I've spent a bit of time looking at this picture of your welds against Sean's. Yours look a lot more like the "stacked coins" that I'm used to seeing and doing. Sean's look different. They're less distinct and there's something of a crystalline look to them. I've never done Tig and I've certainly never approached titanium. Sean's welds show no discoloration and barely show each pass. It just looks like a smooth and even pool. Is it that my idea of what perfect welds look like is wrong?
Thanks,
Ed
Edit- Getting used to the new board. I wanted to post that picture inline but couldn't figure out how.
The two biggest differences you see in Gregor's and my welds are of torch angle and the blending of the start/stopping points. Especially on these small diameter parts, it takes a lot of practice to keep your torch at the same angle relative to pieces to be welded. Any time you tip your torch, the shape of the puddle changes and depending on the direction you tip it, it'll leave a more or less pronounced edge.
The start/stop is another technique that takes a loooong time to get right. I'm still working on it and probably will be as long as I can hold a torch. I have a little more experience than Gregor and that's probably why mine are a little more hidden. Basically, you're trying to reintroduce filler to the weld after you reposition and at the same time are trying to match the puddle size, torch angle, filler direction while adequately blending the new bead into what you've already laid down. Both hands and one foot are independently occupied while you're watching for several things in the puddle.
As for your idea of perfect welds...it depends on what you're looking at. Each material has its own requirements for what constitutes a strong weld and making it look nice in addition is icing on the cake. If you're talking about the "stack of dimes" look with very pronounced edges, I'd guess you're seeing mostly steel and aluminum. With aluminum, even on this wall tubes, each puddle has about half an inch of rod in it and will usually have a very pronounced "toe" https://www.weldersuniverse.com/images/weld_diagram.jpg. On thin wall steel, each puddle will have about 0.050" of 0.035" rod and can have a pronounced toe without adversely affecting the weld so long as it has sufficient throat.
Titanium is a bit different from them in that it has a high "notch sensitivity". "Notch Sensitive" means that if you give it a place to crack, it'll eventually crack. An abrupt transition (toe) is one such place where there's a localized abrupt change in stiffness. The throat of the weld needs to be at least the same thickness as the tube but you do not want a toe on the weld. The edges of the puddle should be blended into the tube to have as smooth a fillet as possible without undercutting so much that you reduce the strength of the tube. I know that it's said over and over that you don't want color in your weld but I don't know that I've ever said exactly why. Those pretty colors mean that you've grown a layer of oxides on or in the weld area. They are MUCH harder than the titanium substrate and even though the oxide layer is only a few nanometers thick, it'll crack when flexed and since it's fused to the substrate, that crack will eventually propagate through the weld or tube wall. That's the biggest reason that titanium has so many extra steps and cautions attached to it while welding.
For photos of VERY good titanium welding but with three distinctly different styles of appearance, checkout Firefly (Tyler Evans), Eriksen/Bingham (Brad Bingham) and Crisp (Darren Crisp). Tyler dabs his puddles. Brad and Darren both lay down the rod but have different torch angles which is why Brads edges are so well defined but Darren's almost look like a smooth fillet.
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