Is there really an M7 screw size in the world? The answer is yes, but it’s not a common size. I came across a question on a forum https://sawmillcreek.org/showthread.php?305619-Bessey-clamp-set-screw-specs-source where a user had lost a set screw from a woodworking clamp and wanted to reorder one from the supplier’s website https://www.besseytools.com/en-us/bessey-tools-north-america . After emailing the supplier to request a replacement, he received no response. So, he decided to try and find one himself but realized the size was M7. An enthusiastic forum member informed him that the typical sizes are M6 or M8, and M7 is quite rare. This discrepancy might be because the user was from the United States, where imperial measurements are more commonly used. I suspected he might not know how to express the size in imperial units.
I checked the metric and imperial size charts and found that his described M7 could possibly correspond to #16 in imperial units.
During the Qin Dynasty in ancient China, Qin Shi Huang unified the various states and established a standardized system of measurements. I believe this greatly facilitated communication. However, today, there are still various measurement systems worldwide. For instance, countries like the United Kingdom, the United States, Canada, and Australia use imperial measurements, while Germany, Russia, China, Japan, and others use the metric system. If the world could establish a universal standard of measurements using the metric system, we wouldn’t need to convert between different measurement systems, which would save a significant amount of time and make it easier for people to purchase products in specific sizes.
What do you think?