It required a compound set up too get the gearing low enough, the screw is turned manually by the hand wheel on the opposite end, which rotates and traverses the work piece under the cutter.
After cutting one scroll, the work piece is rotated 180 degrees, for the next cut to make it a two start.
Rob unfortunately I don't have the luxury of a geared dividing head, As the turns per inch were academic, as it's only for a grease path, the gearing was arrived at with the gears available from the lathe. The scroll is the finished length, the cross drilling is for the retaining pin in the swinging arm, and yes I used it for the 180 location. The spindle is also bored it's full length for lightness.
I made it a while back now, but thought it might be something of interest.