Drilling Pilot Holes

 
Drilling Pilot Holes in Wood:
 
If you are drilling pilot holes for wood screws, then this may help you to know for drill bit sizes that you need to use when getting ready to drill a hole. A pilot hole should be the same diameter as the root of the screw (the center core just below the threads). This allows the bulk of the screw to enter a board without splitting the wood, it still allow the threads be secure in the wood. Common mistakes people make in drilling pilot holes is that the hole is too small or they do not drill a pilot hole at all, and in many cases that can split your wood or makes it difficult for your screw to enter into the wood properly.
 
Inserting screws into woods will depend on the density of the wood, generally for softer woods your pilot hole needs to be smaller while very hard woods will require a larger pilot hole. In either case, both can crack if not properly done right.
 
Hanger Bolt Pilot Hole Sizes
Bolt Size
Pilot Hole Size
Soft Wood
Hard Wood
6-32
7/64
7/64
8-32
9/64
9/64
10-24
5/32
11/64
1/4-20
7/32
15/64
5/16-18
9/32
19/64
3/8-16
11/32
23/64