Lag Bolt Pilot Hole Size
Unlike self-drilling screws (such as wood or sheet metal screws), lag bolts require a pilot hole for installation. This is because they are thread-forming-type screws that create their own mating threads as they advance into the material. This makes them much thicker than other fasteners such as drywall screws or wood screws, and also allows for higher load bearing capacity. As such, they are designed to securely fasten studs or plates to structures without weakening them.
Because of this, it is important to choose the right drill bit for a lag bolt pilot hole. To do this, start by identifying the root diameter of the screw. Then, find a drill bit that is the same size or a little smaller than this value.
For example, if your lag bolt has a root diameter of 3/8 inch, you will want to use a 21/64 inch drill bit to make the pilot hole. This ensures that the lag bolt will fit snugly into the hole. If you use a larger or smaller drill bit than this value, the lag bolt will not be able to fully engage the holes.
When drilling a pilot hole for a lag bolt, it is recommended to use a variable speed drill. This will help to reduce heat buildup, which can damage the material being drilled. Additionally, it is often helpful to lubricate the drill bit to prevent friction between the bit and the wood. A variety of lubricants are available, including beeswax, paraffin wax and bar soap. pilot hole for 5/16 lag screw