Countersink
In some do-it-yourself projects it doesn't matter if the heads of your screws protrude a little from the surface of your lumber. Fencing, garden containers and framework that will be obscured by coverage are all examples of these projects. In other cases, it's vital for appearance, safety and everyday use that the screw heads be perfectly level with, or even below, the surface of the lumber. The solution for these kinds of projects is to countersink your screws.
Steps
- Select a drill bit that is the same diameter as the shafts of your screws. (the solid part, not the threads)
- Measure the length of your screws. Mark that length on the drill bit by wrapping a piece of masking tape around it at that point.
- Drill pilot holes in each point on your lumber that needs a screw. A pilot hole is a guide hole you drill in your lumber for the screws to follow. Drill the hole until the bottom of your masking tape touches the surface of your lumber.
- Pilot holes are also useful for making sure your screw goes in at a level angle. And it helps prevent splitting if you have to drive a screw into a thin edge of lumber.
- Select a second drill bit. This one should be the same diameter as the heads of your screws.
- Measure the depth of the conical heads on our screws. Mark this drill bit to that length using your masking tape. This is unlikely to be more than {{safesubst:#invoke:convert|convert}}.
- Widen the top of each of your pilot holes using the wider drill bit. Drill down until the bottom of the masking tape touches the surface of your lumber. Do your best to keep the wider hole centered on the narrower pilot hole.
- Replace the drill bit with a screwdriver bit appropriate for your screws.
- Set a screw in one of your pilot holes. Twist it in by hand until it can stand on its own.
- Drive the screw into the hole using your power drill. Push firmly on the drill and use pulses to avoid stripping the screw. With the countersink hole in place, the screw should sink easily below the level of your lumber.
Tips
- If you are using soft lumber, like pine, you can often countersink a screw without drilling the wider hole. The momentum you build by running the screw through its pilot hole means you can simply drive the head through the wood to the level of your lumber.
- If you want a smooth surface, you can fill the countersink holes with carpenter's putty before you paint your finished product. This does make it hard to disassemble your project, but it will make a more attractive surface.
Things You'll Need
- Power drill, with drill and screwdriver bits
- Screws
- Masking tape
- Measuring tape
- Carpenter's putty (optional)
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- How to Countersink
