Per discussion at original page, I inverted the ruling lines so the gauge is now a single piece that can be printed without overhang problems.

Update: I added a lower-poly version which should produce a part of almost the same surface quality.

Update 5 May 2022: per reports from makers (see comments), I used Meshmixer to "true-up" the diagonal edge so that it properly crosses the center of a circular object. Use Rev3 now.