Which screw size

Download the Guide. The simplest way to remember how to measure length: Length is the distance from the flat part of the head, to the tip or blunt end of the screw or bolt. Almost all screw head types will either be flat on the top or on the bottom. Most screws are flat on the bottom of the head pan head; round head; truss head, etc All of these are measured from the bottom of the head to the tip.

Flat head, countersunk screws are flat on the top of the head. Back in the day there were just two options, slotted or Phillips. You picked one, picked a length, and were good to go. But the fastener market has made huge strides over the last few decades, giving DIYers better solutions for keeping stuff together. In the days when a screwdriver was the primary means of inserting screws, the Phillips was king. The Quadrex is a combination of square Robertson and Phillips head screws. Adding other factors such as the type of wood, screw material, lateral vs.

Fortunately, there are some general guidelines you can follow that will help you purchase and use the correct type of wood screw for the job. Understanding a few basic principles behind the technology of wood screws will take you a long way toward knowing which type of screw to choose. Wood screws gain power by friction and by the pressure of wood fibers gripping the threads.

When you cut away fibers and remove them, a pilot hole can reduce the grip of the wood around the screw threads, thereby lessening the holding power of the screw. Wood screws need to have enough thread driven into the receiving stock to hold fast. The length of the thread that is inserted into the receiving board is dependent on the forces, either lateral or withdrawal, that will be applied to the boards after they are in use.

Screws designed for fastening wood come in two basic forms: steel or stainless steel wood screws, or utility screws generally known as deck screws. Utility screws are the workhorses of framing carpentry and outdoor woodworking projects. They are available in different types of steel, sometimes corrosion-resistant metals designed to stand up to the chemicals in treated lumber; and they are normally sold by length.

A 6 gauge screw will have a head almost equal to 6 mm wide. Correlation between diameter metric in mm , gauge imperial and head size is complicated. There is nowhere you will find information that can guarantee you can calculate this effectively. It may be the reason why professionals prefer to buy screws personally, to ensure they get the right screw head.

The imperial diameter in 16th of an inch of the screw head is twice the gauge imperial. The formula below can be used to calculate an estimate of the screw head sizes and the gauge. The Gauge is 8. The above formula means that for imperial gauge, the diameter in mm is almost half the gauge.

You should not be disappointed if you do not follow this since not many people know about the said relationship leave alone using them. Screws and their bolts. The table below can be used to match the imperial screw size to the metric size. You should note that the conversion is not exact and therefore margins of errors are allowed.

You can as well use the table below to find the metric screw size from an imperial measurement. The sizes for the rawl plugs and pilot holes have been added. Figure 1. The X axis is the gauge size.

The Y axis is measurement in millimeters. The table below shows common sizes of thread and their equivalent wrench or spanner size. The numbers are used to describe the thread and relate it to the size of the spanner to be used on it.