nut threads type When selecting nuts or screws, many people focus on size first. However, in practice, the thread is the key factor that determines whether parts can be properly fastened. Common thread classifications include: Metric threads vs. imperial threads (UNC / UNF) Right-hand threads vs. left-hand threads Special-purpose threads (such as pipe threads and power transmission threads) These categories may seem simple, but if misunderstood, they can lead to issues such a