The higher the number, the finer the threads, which are best used in metal applications. The fewer the threads per inch, the coarser the threads, the faster the screw will drive and are the preferred threading for wood applications or wood studs. In the case of flat headed screws, the length is measured from the top of the screw to the point.
They do not represent the size of the hole that they will drill but do represent the thickness of metal they will drive through. But we will save that for another tip!
So now you know how screw label numbers work — but how do you choose the right one for proper fastening? You can follow some quick guidelines to help you select the best option for your applications.
Here are three essential measurements every tradesperson should know. There are three main screw measurements: gauge, length, and threads per inch TPI. The first number is screw gauge, which refers to the outside thread diameter. For each gauge size, there is a decimal equivalent.
That number increases by. For the 8 Duraspin screw shown below , the decimal equivalent is 0. Engineering Toolbox has a handy screw size chart that lists screw gauges and their decimal equivalents.
Beyond major diameter, screws have other width measurements. The next important aspect of screw measurement is shaft length. Shaft length is the part of the screw that drives into a surface. The length measurement for a countersinking screw is the distance from the top of the head to the tip. This goes for flat-head, bugle-head, trim-head—and any other countersinking screw where the head can be driven beneath a surface.
For a non-countersinking screw, it's the distance from the bottom of the head to the tip. So for hex-, pan-, button-, round-, and truss-head screws, length is measured from directly under the head to the tip. One exception: an oval-head screw, which can be partially countersunk, is measured from the widest point of the head to the tip.
Below is an example of two non-countersinking timber screws from Simpson Strong-Tie. Gauge refers to the diameter of the drywall screw. In most cases, you will be using either 6 or 8 drywall screws. Keep in mind that as gauge numbers increase, the screw becomes larger in diameter. So, a 6 drywall screw would be thinner than a 8 drywall screw. Free Fit 0. Screws have three basic measurements: gauge, threads per inch, and shaft length in inches.
This means it's a 6 diameter, with 32 threads per inch almost double the normal thread count as a standard wood screw and an inch and a half long.
Wood Screw Diameter: Hold the shaft of the drill bit up in front of the screw. You should only be able to see the threads of the screw and maybe a bit of the screw. If you can't see the threads the drill bit is too big. If you can see too much of the screw , the bit is too small. When the drill is used as a screwdriver, the numbers indicate the torque breaking point.
Higher numbers mean more torque. This feature is useful because you can limit the amount of torque that is applied to prevent screws, or the materials they are inserted in, from being stripped.
When referring to screws , is one description of the type of screw you are dealing with. More formally, tells us the size and also the pitch diameter of the screw.
Taken together, these numbers give us the definition of the screw. The second number 80, 72, 64, 56, 32, 20, etc. So using the above information, a standard thread size of has a major diameter of: 0. Use a bit exactly the same size as the hole when working on other materials. This will account for variables such a wood density and screw type. Hold the shaft of the drill bit up in front of the screw. If you can see too much of the screw, the bit is too small.
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