by Docs Industries | Apr 5, 2018
14 gauge sheet metal is difficult to drill into with our self-drilling eye lag screws. There are several variables which can affect the ability of the screw to set correctly.
Principally, the variables are thickness of the metal, tensile strength of the metal and skill of the installer.
The 750 SD was designed to be installed in 18 gauge sheet metal (0.0478” thick). This is the thickness of most of the metal decking that the 750 SD is installed in.
During installation, the 750 SD threads into the sheet metal. The core of the threads is about 0.190” in diameter. This core is forced into a 0.165” hole made by the drill point.
In other words, the sheet metal is forced to expand beyond the size of the hole drilled by the drill point.
The 750 SD will work with 16 Gauge (0.0598” thick) if the screw is carefully installed. But please note, if too much force is used, the screw could snap or strip out in the deck.
I really do not see how the 750 SD could penetrate and thread into anything thicker than 16 gauge. However, the only way to be certain is to actually attempt an installation.
Perhaps the ELDX self-drilling screw would be a better choice, as it is designed for thicker material and has a larger diameter drill point. We know that the ELDX works well in 12 gauge (0.1046” thick) material. Here again, the skill of the installer is an important variable as the ELDX could “strip out” if the installer isn’t careful.
Many installers use the 750 SD in purlin or red iron.
However, they cannot fully set the screw all the way to the collar in red iron or purlin because the metal has a high tensile strength, even if the metal it is relatively thin.
ICC requires that our self-drilling screws have at least 3 threads protruding through the steel deck panel to be considered properly installed.
Perhaps a better fastener in this situation would be a spring steel clip such as the ADOC14 or VOH14 as these do not require penetration into the purlin structure.
by Docs Industries | Jan 30, 2014
Eye lag screws have long been used in commercial construction to provide an economical and fast way to hang things over head. If you need to suspend something from a wood or sheet metal ceiling, you should consider the eye lag screw.
The acoustical suspended ceiling industry uses eye lag screws almost exclusively to hang ceiling wires. They are economical and can be installed quickly and safely from the floor. These screws can be used in many other overhead applications. Such as hanging lights, signs, electrical cable, data communications cable (CAT5 and CAT6), HVAC ducts, electrical conduit, electrical trapeze, shielded cable and telephone wire to name a few.
Description and load limits:
The eye of the screw is a 3/16” hole punched in the flattened area. The flat end is used to twist the screw in. Screws designed for wood applications are about three inches long and have about an inch and a half of coarse threads that taper to a sharp point; here is no need to pre-drill a pilot hole. Pull out strengths vary with penetration and wood strength, but are usually more than the strength of the ceiling wire (600 pounds). Screws designed for sheet metal are case hardened and zinc plated. They may have a sharp point (for thinner gauges) but usually have a drill point. Pull strength in sheet metal varies with metal thickness. Typically the thinner gauges (22 gauge) are allowed loads of 120 pounds. The thicker gauges (18 gauge) are allowed loads of around 240 pounds.
Methods of installation:
Telescoping pole tools are available that will reach a ceiling of up to 30’. These eye lag extension poles allow you to drive in an eye lag screw and “twist” off the ceiling wire from the ground. There are installation videos available on-line that demonstrate how easy these poles are to use. The LagMaster Plus is the most versatile of the eye lag poles available for this purpose, as it can also be used to hang threaded rod, jack chain and spring steel clips from the ground. In some areas like California, eye lag screws pre-wrapped to ceiling wire are available. These pre-wrapped screws are used to make installation of ceiling wire even faster and to satisfy code requirements for hospitals, jails and schools.
When you are up next to the ceiling, you can use a drill driver jig to twist in the screw. This is the method used when you only have a few screws to install. This would typically require a ladder, scissor lift or scaffolding.
In summary, eye lag screws are surprisingly strong and versatile, whether you’re fastening to a wooden joist or metal decking. While designed to suspend ceiling wire, they can be used to hang just about anything within weight specs.
