In practice, many people have encountered this situation: A screw looks about the same size, but it just won’t go in — or it gets stuck halfway. Most people first suspect size or tolerance issues.However, in most cases, the real problem is: the thread system is different. --- 1. What Are JIS and ANSI / ASME Thread Systems? In screw design, the whole world does not use the same standard. The two most common systems today come from different countries: JIS (Japanese Industrial

Metric and Imperial In hardware parts, machining, and equipment maintenance, it’s common to encounter a confusing situation: you only want to find a screw or a pin, yet the specifications appear in two completely different formats — one written as M4, M6, M8 (metric), and another as 1/4"-20 or #8-32 (imperial). Many people wonder:“Why aren’t these specifications unified?”“Since they look similar, can they substitute for each other?” The answer is: No.Metric and imperial syste