Lesson Learned - 5/25/12

If you have only one set of dies for making screws (metric or english), then you have limited capabilities for making screws. But have if you both metric and english Screw Check'rs, you can sometimes use them to help you get around a lack of properly sized dies. The other day I needed to make a stop arm screw for a bass trombone rotor, but it was a European instrument with metric screws, and we only have American taps and dies. I needed a 3.0x0.5 metric screw (3.0 mm major screw diameter, 0.5 mm thread length), but we didn't have any on hand, so I was in a tight spot. My work-around was to cut a screw with 5-40 American threads (0.125 in. major screw diameter, 40 threads per inch), which is the closest American equivalent I had to a metric 3.0x0.5. In metric screw measurements, an American 5-40 would be about 3.175x0.635. Once I cut that screw, I carefully threaded it into the 3.0x0.5 slot on the metric Screw Check'r to recut the threads to that size. The reason I was able to do that is that the screw I was making was brass, which is much softer than the steel of the threads on the Screw Check'r. For a metal any harder than brass, I can't imagine the technique would work especially well. It's not a perfect solution - the threads weren't perfect - but the screw worked and I needed to get it done ASAP, so there was no time to find or buy a metric die. This way I didn't have to alter the threads in spindle to force an American screw to work, and the screw I made worked perfectly well.