On Friday, a 59-year-old solicitor from Cork, Ireland, named Bill Holohan posted an 11-part thread on Twitter about the history of railway gauges, which is the distance between rails. In the ...

Metric Screw Pitch Gauge. How about a metric screw pitch gauge (top, photo left)? Only $6.05. I used to own one of these when I worked as a journeyman Machinist. Since metric threads are measured by ...