![]() ![]() These charts will typically have three things: Instead, metric measurements specify the thread pitch only, which is the distance between the threads on the screw. ![]() Left-handed screws loosen when you turn them clockwise and tighten when turned counter-clockwise.Ī metric screw size chart is fundamentally different from imperial screw charts since they don’t contain information on the number of threads per inch. Left-handed screws are threaded in reverse, which may confuse you if you’re not aware of the LH symbol. ![]() Right-Handed or Left-Handedįinally, left-handed screws are labeled with the symbol LH, right after the tolerance class. There may also be the letter A or B next to the number, which indicates a slightly different size. This is because they have more space between their threads. Size 1 screws fit more loosely than size 2 screws. There are five tolerance classes, from class 1 to class 5. You’ll find it specified after the screw length. The tolerance class indicates which type of holes or nuts the screw can fit into. 5 at the end of the callout, this means that the screw length is ½ inch long. When reading the callout on a box of screws, you’ll see the screw length specified at the very end of the callout. The screw length is measured from beneath the screw head to the tip. These screws are known as non-countersinking. Some screws, like truss-, round-, hex-, button-, and pan-head screws don’t go all the way into the surface. Screws that can be driven completely into a surface are known as countersinking screws. ![]() This means that the head of the screw is part of the screw length. Some screws have heads that can be driven completely into the surface. The shaft is the part of the screw that goes into the surface. Just like with nail sizing, a screw length is the length of the shaft. If the screw is from the fine series, it’ll have 36 threads per inch (#8-36 UNF). This screw will have 32 threads in a one-inch section of a coarse screw (#8-32 UNC). It’s specified right after the screw gauge. TPI stands for the number of threads per inch. Knowing this will help you know what drill bit sizes to use when drilling into wood, metal, plastics and any other material. If the screw has an outside diameter of 0.25 inches, the gauge size will be ¼”, and so on. #0 has an outside diameter of 0.06 inches, while #12 has an outside diameter of 0.216 inches.Īfter #12, the gauge size is labeled according to the outside diameter. The screw gauge is the diameter of the outside thread in inches, better referred to as the “major diameter.”Īnything less than ¼” will be labeled from #0 to #12. There’s also the extra-fine screw thread standard (UNEF), but it’s not as popular as the other two. There are two thread standards under the UTS chart: course (UNC) and fine (UNF). So, to sum up, here are six terms you should familiarize yourself with within the UTS system: This could come in handy if you’re converting from the metric system to the imperial system, but it’s not something that UTS screw charts generally have.įinally, the callout on the screws box may have a tolerance class number, the LH symbol if the screws are left-handed, and the screw length. Our extensive screw chart also specifies the screw pitch in inches, which is the distance between each thread. Whether you’re trying to read a screw chart or a screw label with the callout printed on it, you should familiarize yourself with both systems How to Read a UTS Screw Chart (Imperial System)Ī UTS screw chart will typically have three things: the screw gauge, the number of threads per inch (TPI), and the thread standard. This means that you’ll have to follow the standard screw sizes of ASME/ ANSI, which is called the Unified Thread Standard (UTS).Īll measurements in the UTS system are in inches.įor the rest of the world, you’ll probably be using the metric system, which follows the ISO screw thread standard. If you live in the United States, you’re among the three countries in the world that use the imperial system. Let’s get started! How to Read a Screw Chart I’m here to tell you that sizing the right screw doesn’t have to be guesswork anymore!īy the end of this guide, you’ll be able to confidently read a screw size chart and decipher all the measurements on a screw callout by yourself.įrom metric and imperial size standards to all the other related intricacies, I’ve got it all covered below. The first time you read the label on a box of screws, you’ll probably come across a lot of confusing numbers that seemingly don’t make any sense. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |