Drill until your pilot hole is the same depth as the length of your screw or nail. Many experienced do-it-yourselfers can eyeball the depth, but if you aren't yet that experienced, you can use a drill stop to mark the appropriate depth.
If you are joining two pieces of wood then drill a pilot hole through both pieces of wood, ideally clamping them first or in some other way ensuring they don't move before driving the screw, making the pilot hole pretty pointless.
A very easy way to manage drilling depth is to measure from the tip of the drill bit the depth you wish to go, then mark that length with a small piece of tape. Drill down into wood until you reach the tape touches the surface of the wood.
Pilot holes are necessary if you're drilling into hardwood, laminate, or need a precisely located fastener. They're also recommended if the wood is likely to crack, or if appearance is important. You can skip the pilot holes when doing a rough build with softwood where appearance isn't important.
Drill until your pilot hole is the same depth as the length of your screw or nail. Many experienced do-it-yourselfers can eyeball the depth, but if you aren't yet that experienced, you can use a drill stop to mark the appropriate depth.
Choose the Correct Size Drill Bit
As I mentioned earlier, pilot holes should be slightly smaller than the screw's shank for softwoods, slightly larger for hardwoods, and about 1/64″ larger than the screw's shank if you're unsure of the wood.
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.
As a general rule of thumb, your pilot hole should be slightly smaller than the diameter of your screw. This will remove as much material as possible, which will reduce the likelihood of splitting, but will still leave enough material for the screw's threads to grip into.
Depth stops, also called drill stops, are collars that fit around your drill bit. They allow you to drill a specific depth, and prevent the drill from drilling any deeper. Drill stops are sold in sets containing a variety of sizes for use on different sized drill bits.
“One common rule is to avoid drilling around light switches and sockets, as the electrical wires can go horizontally and vertically around these fixtures,” Williams explains. “You can also get an idea of where wires and pipes run by looking in the attic and basement to see where they go up or down through framing.”
Squirt wood glue into the hole, and then insert toothpicks or matches until the hole is filled. Tap them lightly with a hammer to push them into the hole as deep as possible. Let the glue dry and break off the protruding ends of the toothpicks or matches. Now you can screw the screw into the repaired drill hole.
If your pilot hole is too big, your screw won't stay in, but if it is too small, you will have trouble getting your screw in, and you might even strip it. So choosing the right size drill bit for your pilot hole is necessary to ensure your project runs smoothly.
Wet or warped lumber is a common cause of splitting. Watch your screw placement: Where you drill your pilot holes is a critical aspect of building sturdy structures as well as keeping the wood from splitting. It's especially important not to place screws too close to the ends of the plank.
You're using low-quality bits
Blunt bits have to work much harder, meaning that there is a higher chance of bits getting stuck or not getting through the material. Cheap bits can also get stuck more easily, with an added risk of bits breaking in your workpiece. They can even damage your drill as well.
For #10 screws, it is best to know the appropriate pilot hole size on the intended wood, whether it is hardwood or softwood. As referenced below, the drill bit size that matches a #10 screw is 7/64 and 1/8 for softwood and hardwood, respectively.
A 1/4-inch chuck is sufficient for a light-duty drill driver. A 3/8-inch drill accepts a wide range of bits, making it versatile for common tasks around the house. A 1/2-inch drill handles heavier applications.
Deepest drillings
The Kola Superdeep Borehole on the Kola peninsula of Russia reached 12,262 metres (40,230 ft) and is the deepest penetration of the Earth's solid surface. The German Continental Deep Drilling Program at 9.1 kilometres (5.7 mi) has shown the earth crust to be mostly porous.