Some construction pics.
Main beam: sawn from 1" x 3/8" flat bar, in 4 jaw chuck for turning handle spigot.
Main beam: turning between centres

Main beam: held by handle spigot to turn, drill & tap 5BA for centre locking screw.
Main beam turning completed.
Screwcutting the 3/16" x 20tpi screw (left hand).
Indexing block to mill square section on end of beam.
Blocks soldered together for machining scriber arm & locating jig.
Square hole for beam in end plate.
Set up for for drilling centre for screw using locating jig.
Milling ivory handle using dividing head to index 12 facets.
Scriber arm with drill rod insert (for hardening) and filing buttons.
Roughing out scriber arm to filing buttons.
Component parts.