I've done a lot since the last post, so this is an attempt at catching up. Much of December was a loss as far as the bike was concerned. Though I did totally remodel 2 rooms in my house... so not a total loss I suppose. And it made my wife happy, which is always a good thing. First some shots of the current state of the thing...
The first thing I did was get the seat mounts done. These use a sliding plate system that is bolted to the sides of the maintube via brazed-in weld nuts, similar in idea to what volae uses. There are 4 holes in the tops of the plates that are tapped and allow gross adjustment of the seat, the slots allow fine adjustment. The mounts to the seat are just pieces of angle stock (actually taken from the bathroom remodel, they had been being used as trim around the radiator... really ugly). They are held on to the seat with small machine screws. The angle stock is tapped and I will also add nuts for extra holding/locking when I do the final assembly.
I also made the mounts for the "shoulder" attachments to the seat. The upper part of the telescoping tube that holds the seat up is made from 6061 T6 Aluminum, and the top part is made from Al rod that is crossdrilled, tapped, turned, and milled. I then bonded it into the top of the tube with JB-weld epoxy.
The idler mount is made simply from a piece of square steel tube that is crossdrilled for an 8mm bolt. it will be attached with nuts on either side. I still need to make chain keepers. I also need to find a slightly longer bolt as the threaded portion of the one shown is too short. The idler itself is from PowerOn cycling.
The steering column is attached to the fork steerer using a steerer extender that I found at the local recycled bikes place for a couple $ and then turned down on the lathe.