Using the proper screws is essential for long-lasting and properly functioning door hinges. If the incorrect screw type is used for mounting a door on a hinge, corrosion over time may wear away at the screw and cause it to break. Proper screw size, material type, head type and thread type are the general specifications available for screws. Regardless of screw type, screws should not be installed until the holes have been pre-drilled with a small drill bit and electric drill to prevent cracking of the lumber during screw installation.
When referring to the size of a screw, there are a variety of measurements being specified. Screws are sized by a number pertaining to the head size and shaft size, such as a #8 screw, which means the diameter of the shaft of the screw. Screws also have different lengths, which are measured in inches, such as a screw #8 that is 1 inch long would be referred to as an 8 by 1 inch screw. The size of the screw needed for a specific hinge will be determined by the hole size in the hinge, the weight of the door and the material you will be mounting the hinge to. The head size of the screw should fit perfectly into the hole in the hinge and be flush with the hinge when installed. The screw should be long enough to sink into the material an adequate distance to hold the hinge to the frame. The heavier the door, the longer the screw should be, however, the screw should never be longer then depth of the frame, which would cause the screw to protrude out the backside of the frame.
Screws come in a variety of types designed for the material they will be attached to. Some of the screw types available for hinges are sheet metal, wood and brass. The most important thing to remember when it comes to material types is that the screw should match the material it will be secured to. If the hinge is brass, the screws should also be brass, because if they are another type of material the metals will wear against each other over time and break down. Drywall screws are readily available in home repair stores, but should be avoided, because they break easily and rarely match the hinge material.
Hinge screws should all have countersunk head types, which means the diameter of the head bevels inward toward the shank of the screw, allowing it to "sink" into the material and create a flush surface once fastened. Hinge screw head types vary in terms of the drives or the shape on the top of the screw for driving the screw into the material. The two most common hinge screw drives are flathead, which looks like an indented line in the centre of the head of the screw and the Phillips head, which looks like a plus sign. Other screw head types that are found more in un-assembled, prefabricated furniture are square heads and Allen heads, which look like an indented hexagon on the head of the screw.
The thread type of a hinge screw refers to the number of threads along the length of the screw. This is referred to usually by the number of threads per inch of screw. The more threads per inch, the better the screw will grab into the material with less likelihood of splitting and cracking. However, since the threads are closer together, there can be more risk of the screw loosening and pulling out over time. Most hinge screws have between 15 and 20 threads per inch. Hinge screws are also typically self-tapping, which means they will pull themselves into the material without additional assistance such as hammering, but pre-drilling is still recommended to reduce the risk of cracking and splitting.