Lag bolts (also known as lag screws) are threaded fasteners with hex heads that are secured with wrenches. They’re used in woodwork and masonry applications to join materials, typically for structural purposes. Unlike self-drilling screws such as wood screws, lag bolts require a pilot hole before they can be screwed in.
When drilling a pilot hole for a lag bolt, it’s important to choose the right drill bit size. Too small and the lag bolt will break when installing it. Too large and the bolt may not penetrate the material it’s being installed into. Using the correct drill bit ensures the screw will have sufficient shear strength to hold the weight of the material that it’s being attached to.
For a secure installation, the lag bolt should be driven two and a half to three times its major diameter into the material being joined. Driving it any deeper risks splitting the wood or ruining the lag bolt’s threads.
To avoid wasting time and money, always check the shear values of a drill bit before purchasing it for a particular application. The shear value is a measure of the bit’s ability to resist shear forces exerted on it by hard, dense materials. This is a good indicator of the type of material you’ll be working with, as well as how much pressure your lag bolts will need to withstand when being installed. The shear value of a drill bit will vary depending on the manufacturer and the type of material that the drill bit is made from. pilot hole for 1/4 lag screw
