In our metric screw size chart, we provide the pitch for both coarse and fine threads. 3. Screw Length

We’ll be explaining each definition of these to help you read our metric screw size chart. 1. Screw Diameter The thread values are derived from rounded Renard series. They are defined in ISO 3, with "1st choice" sizes being from the Rˈˈ10 series and "2nd choice" and "3rd choice" sizes being the remaining values from the Rˈˈ20 series. [5]The shank is the part of the screw that lies beneath the screw’s head. It can be threaded all the way to the tip, partially-threaded, or not threaded at all. 3. What Is the Difference Between Metric Machine Screw Sizes and Wood Screw Sizes? The screw pitch is represented by the second number you see in the callout. It represents the distance between each thread on the screw in mm.

There is a huge variety of types of screws and bolts available in the market that are available in different drive types, head styles, materials, sizes and thread pitch. They can be used with a range of complementary nuts and washers to prevent loosening once in place. Some of our most popular fixing categories include: Typically, screw callouts contain three numbers whether for imperial or metric ones. Metric callouts usually contain:Basic profile [ edit ] Basic profile of all ISO metric screw threads, where the male part has the external thread The relationship between the height H and the pitch P is found using the following equation where θ is half the included angle of the thread, in this case 30°: [3] H = 1 2 tan ⁡ θ ⋅ P = 3 2 ⋅ P ≈ 0.866025 ⋅ P {\displaystyle H={\frac {1}{2\tan \theta }}\cdot P={\frac {\sqrt {3}}{2}}\cdot P\approx 0.866025\cdot P} D min = D maj − 2 ⋅ 5 8 ⋅ H = D maj − 5 3 8 ⋅ P ≈ D maj − 1.082532 ⋅ P D p = D maj − 2 ⋅ 3 8 ⋅ H = D maj − 3 3 8 ⋅ P ≈ D maj − 0.649519 ⋅ P {\displaystyle {\begin{aligned}D_{\text{min}}&=D_{\text{maj}}-2\cdot {\frac {5}{8}}\cdot H=D_{\text{maj}}-{\frac {5{\sqrt {3}}}{8}}\cdot P\approx D_{\text{maj}}-1.082532\cdot P\\[3pt]D_{\text{p}}&=D_{\text{maj}}-2\cdot {\frac {3}{8}}\cdot H=D_{\text{maj}}-{\frac {3{\sqrt {3}}}{8}}\cdot P\approx D_{\text{maj}}-0.649519\cdot P\end{aligned}}} The minor diameter D min and effective pitch diameter D p are derived from the major diameter and pitch as There are a range of acronyms and letters that you often find on screw boxes or in their online descriptions. Here is a summary of the most common, and what they mean: