On the mechanical side:
- It's a 2008 model, so the knob is secured with a roller pin, not a grub screw, good.
- My current idea is to tap the existing hole in the rod - sounds like folks have had success with an M4 tap.
- On the new wooden knob, instead of drilling straight through side to side like the OEM knob, only drill through the backside (probably slightly undersized).
- Counterbore the backside hole.
- Use a socket head M4 to pass through the knob, and thread directly into the rod.
- Should be plenty secure to hold the knob, and with the screw countersunk, should be fairly clean from the rear, and not at all visible from the front.
Also also, thinking about the shape of the boiler cap, lever handle, portafilter handle, tamper handle.... and maybe some other accents. Once I get further along with that, maybe I'll rename the thread or spin that off elsewhere.
Anyway, does my steam knob fitment make sense? I can do up a little schematic as well if needed.