I have added a drawing to the files - QUILL-SCALE.PDF
This has two possible scale rings that can be used with the quill feed. One is marked 0 - 30 mm in both directions, the other is marked ¡À15 mm. They can be printed onto thick card and cut out - if the central hole is a snug fit on the handle you can zero them like any other scale ring. I tried this when I had my SL and it works well enough. I intended to print one on acrylic with a laser cutter, but then my SL departed, and I never took it any further. I would have added a springy bit in the middle so it had better grip on the shaft, but taking into account how brittle acrylic is.
Just make sure the print is at 100%, not adjusted for paper size. It's nominally A5 (210 ¡Á 148 mm, 8 1/4" ¡Á 5 13/16"), so small enough to fit on most standard sheets.
A more thoroughly engineered fitting is possible, and I reckon working to abut 0.1 mm should be realistic. Calculating the markings is easy enough - the rack is 1 mod, so the linear pitch is ¦Ð, 3.14159 ... and the gear has 10 teeth, so the full circle represents 31.4159 mm (1.237"). The maximum travel is just under one turn of the shaft, so there is no problem with the scale running over 360¡ã.
Thinking about it now, I do still have an SL headstock that needs a rebuild, and I was going to make a new lever for it. Maybe I could do a scale for it at the same time. If so, I'll post whatever I do.
