What size pilot hole to drill for #8 screw?

Wood Screw Pilot Hole Sizes
Screw SizeHard WoodSoft Wood
Tapered BitStraight Bit
#75/32"3/32"
#811/64"7/64"
#93/16"1/8"
A.

What size of drill bit is used for a pilot hole in lumber?

Drill bit sizes for pre-drilling (most commonly used sizes in bold)
Screw SizePilot hole size for hardwoods*Pilot hole size for softwood**
#13/641/32
#23/643/32
#31/163/64
#41/163/64
  • How deep is a pilot hole?

    Pilot holes guarantee that your screw won't break off and your wood won't crack. For most hardwoods, the pilot hole should be at least as large as the screw's minor diameter. If the screw has deep threads, or the wood is very hard, the pilot hole should be another 1/64-in. larger than the minor diameter.
  • What is a taper drill bit used for?

    Uses for Taper Drill Bits. Taper Point Drills were engineered to be used to pre drill the pilot holes for the shank and threaded portion of a wood screw. The object, of course, is to use the proper size drills and drill to the proper depth to insure the best holding power from the wood screw.
  • What is a shank hole?

    Drill Pilot Holes. A pilot hole works in conjunction with a screw-shank clearance hole. A pilot hole is a small-diameter hole bored into the bottom board. Its purpose is to provide a path for the screw to enter the board without splitting it.

Updated: 25th August 2018

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