When Carl sent me this picture of the seat tube insert getting welded, I had to ask him what a seat tube insert is. Apparently he insert is a piece that is welded into the tube in order to allow a 27.2 seat post to fit into a tube with a much larger inside diameter.
(click on all images for full size)
Before anything gets welded, Carl tacks everything together so it stays put in the precise angles he wants them at. Per his website, he tacks them slightly off from the final geometry since over time he’s figured out that the process of welding actually un-aligns the frame a bit. This way, if the frame is purposefully mis-aligned to start out with, hopefully it’s pretty much perfectly aligned when he’s done welding. This is the seat tube and bottom bracket getting tacked.
Now that the seat tube and bottom bracket are tacked together, he’ll go through the welding process. Through the next pictures you’ll notice everything nicely sealed up so that he can pump in Argon gas. Argon gas is an inert gas that prevents the titanium from being contaminated during the welding process.
Here’s the same tacking process for the entire front triangle. This is a nice view of the jig holding the whole thing together in precise angles
And here’s the welded front triangle. You may not be able to see this, but Carl machines the front of the head tube down. This allows him to take off a bit of weight, and I think it’s just a cool feature. Carl calls the machining of material off the head tube “off-axis” or “eccentrically” machined.
Tacking the chain stays. Alignment table in the background.
Before Carl can put the seat stays on, he’s got to put the dropouts on them. Those are some beefy dropouts. I’ve heard that Carl is going to new dropouts.
Per the guys at roadbikereview.com, these are the old design of the dropouts. He’ll have his new design available next year. At first I was pretty concerned with these dropouts. They are beefy and not particularly pretty. These “hoods” allow the dropout to be extremely stiff and really minimize any flex that’s happening in the hub/axle and dropout interface. Anyway, here’s a picture of the new design that not on my bike. Notice that the “hoods” are still there to provide a second plane giving them the same stiffness.
And here he is having tacked the seat stays – the rest of the frame is now completely welded, so just a couple more welds to go. Notice the thing is still completely sealed up so no external air can get in. Also, the little bridge for the brakes are not there yet – Again, no point welding them on if you haven’t tacked them onto the frame yet. That will be part of finishing the frame.
