Pilot or lead holes are typically used to ease the installation of large diameter lag bolts. Unless specified, the lag bolts we make will have a semi-cone point, not a gimlet point typically supplied on smaller import product. Full points are not needed for large diameter lag bolts, because pilot holes should be drilled to ensure the heads do not break when torque is applied. Refer to the chart below for commonly accepted hole sizes.
There are a number of variables that may change the required pilot hole dimensions including: bolt length, diameter, and wood species. Consult an engineer for questions regarding specific applications.
|Nominal Diameter of Lag Bolt, inches||Shank (Unthreaded) Portion, inches||Diameter of Pilot Hole, inches (Thread Portion)|
|Table provided by OBEC Consulting Engineers|