Can someone explain how all the planks of the bog oak fit together so perfectly? The article says go to their instagram for details but I'm not really getting a whole lot when I click on individual photos.
I haven't seen their page, but I've seen this kind of thing before. After lining up approximately where things should fit, one piece is cut in a smooth curve just back far enough to remove the live edge. The other piece is cut to match that. This can be done using router templates. IIRC there's some trickiness with the size of the router bearings / guides to account for cutting on one side vs. the other.
For the scale they are doing, they might be able to set up a more customized solution. For example, a router attached to some guide tracks like a https://en.wikipedia.org/wiki/Pantograph
digging through their Instagram posts, it appears as though they've developed a newish technique for this which they call a "river joint." They match the not perfectly straight edges of adjacent boards as well as they can, then they square up and rout a tongue and groove into the edges. Where there are small gaps, they add small filler pieces as necessary, but try to minimize that.
It seems like a beautiful but laborious process that is mostly applicable to a very high effort piece like this.
It looks like they cut a single 43ft board from the oak, then cut that into 4 planks for the kiln and milling process. After that completed they would join them back together. You lose at least an 1/8" for the blade width plus whatever they had to trim due to cupping, but that could be very difficult to see in the final top.
No. There was only about 2/3 of the round log remaining, and they cut (a mix of quartersawn and riftsawn) ten planks out of it. All were full-length, but some were decidedly narrower or rougher than others. They chose four main planks to build the tabletop around, with a fifth full-length cut from one of the scantiest planks to wed the book-matched left and right center planks together, in the center.