Wood to metal screws are a great way to quickly fasten to metal, even metal up to 3/8″ thick. If you are needing to fasten 2x material to an I beam or trailer bed, you likely are not looking forward to drilling and tapping a bunch of holes. Using the right screw will make your life much easier. What is the right screw? You need a flat self drilling and tapping screw preferably with wings. These screws are typically a 1/4-20 machine thread screw with a drill point on the bottom. The screw then transitions into a thread cutting section and finally the 1/4-20 thread. You may find a 10-24 thread but likely they have a shorter drill depth and are more prone to snapping becuase of the smaller diameter. The wings work to clear out the wood and snap off when the wings hit the steel. The wings prevent the wood from “jacking” that is rising up on the screw threads. I embedded a video below that shows how they work into a steel eye beam.
Installing these self drillers for wood to metal is pretty straight forward. Keep a few things in mind. First off, for fastening 2x lumber to steel, the screws will typically drill in steel up to 3/8″. Deeper than that and they will bind up and snap. Weld points can cause problems as well, the weld is simply to hard for the screw to cut into. The screws will require a fair amount of force to go in so be prepared to lean on the drill a little. As for the best tool for installing self drilling wood to metal screws like these, the more speed the better so an impact drive will serve you better than a drill. You really need an 18 volt or more impact driver, the small little 12 volt drivers have their place but here you need more power and speed. If you are using treated lumber, make sure you have a screw has a coating or you may even consider stainless. Zinc will not only rust but it can react with the chemicals in the treated lumber and cause a reaction that can make the screw brittle and more prone to failure. As for the drive, I have had good luck with the phillips head. Just make sure you use the correct bit tip, #3 by the way. Torx or star drive are also available.. Below are a couple of links for screws I would recommend for mounting 2x wood to steel.
So there are a few basics on self drill and tap screws made for attaching wood to metal, in particular 2x material. If you have the right screw, the right bit tip and the right impact driver, your job will be much easier than drilling and tapping all those screws!
Installing Wood To Metal Screws For 2x Lumber
