• MLCS Woodworking

How To Countersink Screws The Right Way

By: Chelsea Rodgers

Believe it or not, but when you have countersink screws in your project done the right way, your work instantly looks top of the line. It’s not that hard to learn, or do. When you have the right tools (sometimes with no special tools), your projects can achieve that flawless finish. So, let’s talk Countersink Screws!

Countersink A Screw?

A ton of projects are put together with countersink screws. But what does it mean to countersink a screw? When you drive a screw into any material, you typically stop when the screw head hits the surface. To countersink that same screw means you are going to drive it below the surface.

Types of Countersinks.

Just like everything else in woodworking, there are a few different ways to countersink a screw. The secret is to use the special bit that is made for the method you are using.

Predrill Countersink Bit

A pre-drill countersink bit makes a pilot hole for the screw and the conical countersink hole at the same time. This method easily gives you consistency as you move from screw to screw. The Tapered Drill Bit HSS Countersink Set (MLCS item# #9195H) are good bits to use for this. They come in a set of 7, giving you various sizes and lengths.

The Tapered Drill Bit HSS Countersink Set

(MLCS item# #9195H)

Stand-Alone Countersink Bit

High-Speed Steel Countersink

(Eagle America #370-2300)

The second method is to use two different drill bits. The first one predrills a hole for the screw. Then you take the second bit, like the High-Speed Steel Countersink (Eagle America item#370-2300), to make a cone-shaped hole in the surface of the wood that will allow the head of the screw to sit below the surface.

This method takes a little more time, but can create cleaner holes. A stand-alone countersink bit can usually be used on both wood and metal, making it more versatile if you work with both on a regular basis.

Quik-Change Countersink Drill Bit And Driver

If you hate switching between a countersink bit and a driver bit constantly, this is what you need! The Quik Change Countersink Drill Bit Set. (MLCS item# #9365H) These bits will help you countersink in one easy step.

Quik Change Countersink Drill Bit Set.

(MLCS item# #9365H)

How To Countersink Screws

Before you start drilling, there are a few things to consider.

· Do you plan to fill the hole with wood putty or a plug?

· If you’re painting your project, sinking the screw heads slightly below the surface and filling the hole with wood putty will give you a flawless look.

· If you’re leaving the screw head exposed, you want to drill the hole so the screw head will be flush with the wood surface.

· How large is your screw head? Is it flat or rounded? What angle is the underside of the head?

· A flat screw head with a tapered underside is the best choice for countersinking screws. Make sure your screw head size matches the size of the countersink bit you plan to use.

· If you’re attaching a thin piece of plywood or metal to a thicker piece, you may want to find a screw head with a 100° angle rather than the standard 82º head. This gives it more surface area to hold on to and there’s less risk of it pulling through the material.

Mark The Position

Mark the position of each hole on your workpiece with a pencil. If you’re joining two pieces at a right angle like you see below, draw a line to mark the center of the board you plan to drill into.

helps you determine exact centers on the edges of boards.

The Marking Center Finder (MLCS item#9561)

Choose The Correct Countersink Bit Size

The size of your countersink bit should match the size of the screw you plan to use. The number size of the screw is typically on the packaging. #6, 8 and 10 are most common. Make sure the screw has a flat head with a conical shape underneath.

Adjust The Countersink Bit Height

Set the height of the countersink to match your screw length. To do this, insert the corresponding hex wrench into the hole in the side to loosen. Then raise or lower it to match the depth of the screw you’ll be using in your project. 

Drill the Countersink Hole At The Marked Spot

Line up the tip of the drill bit with the mark you made earlier. Start the drill off at a faster speed to sink the bit cleanly, then slow it down to make the countersink. Drilling the countersink hole too fast can produce tear-out or make it too deep.

Test The Fit

After making the first countersink hole, test the screw to see how it sits. If it’s too high, the screw head will rise above the surface of the wood. Too low, and it will take more time to fill the hole. By testing the fit on a scrap piece of wood first, you can perfect the countersink hole before drilling into your project!

How To Countersink Without A Bit

If you don’t have a countersink bit, there are two ways you can create one using standard bits.

Two Drill Bit Method

Predrill a hole that matches the diameter of the screw you’re using. Place a piece of tape on the bit to mark a stopping point the same length as the screw, so you don’t go through the material.

Next, choose a bit that is slightly larger than the screw head. Make a shallow hole for the head of the screw to sit just below the surface of the wood or metal. This doesn’t make the cleanest hole in the world, but it will do if you plan to cover it with wood filler later anyway.

Philips Head Method

If you are out on the job and find yourself without a countersink bit, this method will work in a pinch. Take your Philips Head bit and place it in the spot where the screw will go.  Start the drill and move it around in a circular motion, widening the hole as you go until you get the desired size. 

This method makes a surprisingly clean hole (the center one), although it’s a little too small. The screw head sits just slightly above the wood surface and wood filler wouldn’t be able to hide it.

Hiding The Screws

After you’ve finished countersinking your screws, you can leave them as is, or you can make them disappear! There are two different methods for hiding countersunk screws.

Hide The Countersink Screws With Wood Filler

This is my preferred method of hiding screw heads when the project will be painted. Use any type of wood filler or putty to cover the hole, overfilling slightly.

Once the putty is dry, sand it smooth and paint your project. Poof, the hole is gone!

Hide Countersink Screws With Wood Plugs

By drilling your countersink hole deeper or using a special counterbore bit, like the bits in the 8 Piece Plug Cutters Set (MLCS item #9160H), which screws both in countersink and counterbore. You can fill in the holes with a wood plug that disappears into the grain. You can also use a contrasting wood color or a button to show off the hole instead!

8 Piece Plug Cutters Set

(MLCS item #9160H

Countersink Lag Bolts

If you are building a deck, you will usually have to install lag screws or lag bolts to hold the framing components together.  You can install them and leave the head and washer exposed, or you can countersink these as well.

First, measure the width of the screw portion of the lag and find a corresponding bit. Then measure the size of the washer that you will be using and locate a paddle bit just slightly larger.

To make the countersink hole that will hide the washer and bolt head, drill the hole for the body of the lag and then come back, and using the paddle bit, cut a hole deep enough for the washer and the lag head to sit below the surface.

How To Countersink Drywall Screws

The basic premise behind driving a drywall screw to its proper depth is knowing when to stop! The strength of the drywall is primarily in the paper face, so the ideal countersink in drywall doesn’t break the paper face; it just sinks slightly below the surface. Trying to do this by “eye” will usually result in most of the screws breaking the paper and ending up inside the gypsum. The 4-Piece Professional Countersink Set (Eagle America item#365-9399) will help you avoid this.

The 4-Piece Professional Countersink Set

(Eagle America item#365-9399)

How To Countersink Screws In Metal

While you may not come across the need to do this very often, it’s nice to know that most everything you learned about countersinking screws in wood, will be applicable when it comes to metal. The main difference is that you will need bits that are made to cut into the metal.

You can find the countersink bits that will work for metal, but these usually do not come with a pilot bit. You will need to find a bit that corresponds to the body size of the screw and drill that hole first. Just as in the case of wood, place a piece of tape on the bit to mark your desired depth. Then you can use your countersink bit to make the conical hole for the screw head. The High-Speed Countersink we talked about earlier, is strong enough to tackle metal cuts.

Keep these pointers in mind when you putting in those countersink screws, and you will take your project to the next level!

#MLCS #woodworking



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