Drilling Lag Screw Pilot Holes
|Pilot Hole Size for Softwood||Lag Screw Diameter||Pilot Hole Size for Hardwood|
Lag Screws in Softwoods
When drilling into softwoods, it’s always worth trying a smaller sized bit. The lower density wood fibers allow for greater compression when receiving the screw. This results in an overall tighter fit and more secure fastener. There are a few exceptions to this like aromatic cedar and other hard softwoods. If you aren’t sure how if you should test a smaller drill bit, we have a chart with all the hardness ratings for North American softwoods. Though there’s no need to countersink your lag screw, we recommend smoothing the surface.
Lag Screws in Hardwoods
The most challenging part with hardwoods is driving in the actual lag screw. If you have a pack of nut setter bits, you’re in good shape…at least for the smaller sizes. For the other users out there that will be using a socket on a 1/4″ hex shank, it’s a different story. As the lag screw enters deeper into the pilot hole, the socket will likely ground out before the screw is fully inside. When you encounter this, stuff some small washers into the back of the socket. This will effectively make the socket shallower when it wraps around the lag screw’s head. Do be mindful that it is of course safer and quicker to use nut setter bits.
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