Choosing the Right Fastener (Part 2 Screws)

Last week we talked about how to pick the right nails for the job. You can read that post here. This week we’re going to discuss how to choose the right kind of screw for the job.

There are tons of different kinds of screws. While you don’t have to deal with pneumatic sizing like you do with nails, you have lots of variety in screws.

We’ll talk about sizing (which is important) toward the end, but first I want to discuss what I feel are the two most distinguishing features of screws. Drive type and head style. These two options can make or break your project.

Screw Drive Type

For years, the options for screw heads were pretty simple. Flat head. That was the only real option for most homes. The first screws were invented in the late 1700s and the first screw driver came along in 1800. I’m not really sure what good screws did before someone invented the first screwdriver, but that a discussion for another time.

In 1934, the Phillips head screw was born and sold as a “self-centering” screw that worked better for the automated manufacturing that was beginning to take off in the young automotive industry. Today, there are over two dozen different drive options.

There are Square (Robertson), Hex, Torx, Pentagon, Slot, Cross, Pozidriv, Hexalobular, TTAP, Bristol, Clutch. The list is very long. Many of these are for very specific applications that most of us will never use so I’ll just talk about the most typical options over the standard flat head.

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  Phillips – After all these years, this is still the most common screw drive type. There really aren’t many applications where this type of screw isn’t available. This is a good all around screw. Its weakness is that it can be easily stripped if you don’t line up the screwdriver.

• Square (Robertson) – Another very popular type of screw drive is the square head nicknamed after its inventor P. L. Robertson. Square drive screws have excellent torque and are less prone to slippage or stripping. They are a particularly popular choice for cabinetmakers and decks.
• Torx – Unlike Phillips head screws which are designed to “cam out” if the screw is over-tightened, torx screws are designed to not cam out under any circumstances. This design gives them extraordinary torque and driving power for some of the toughest applications. A good application for this type of drive would be with long lag screws for heavy fastening.

Screw Head Style

The other important aspect of choosing screws is the style of the head. Some head styles allow the screw to be driven flush with the surface while others assure that the screw heads remains above the surface. Knowing which to use can make or break your project. Here are the most typical head styles.

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  Flat (Countersunk) – Flat head screws (often simply called “wood screws”) are designed to be driven flush with the surface of the workpiece. The chamfered bottom of the head and flat top allows the screw to do this perfectly. This is possibly the most common screw in standard construction.

• Oval – Oval head screws are chamfered at the bottom and designed to work just the same as flat heads. The only difference is that instead of a flat top they have a rounded top. The rounded top serves no purpose other than appearance since these screws are most often used for visible hardware and finishes.
• Pan – Pan head screws are designed to rest on top of the workpiece. These screws are often used for fastening metal pieces together as they provide excellent holding power due to their wider head.
• Bugle – These screws are the style you typically find used in drywall and deck screws. The flared head design allows the screw to be driven flush with the surface and provides stronger holding strength than standard flat or oval head screws.

A Few More Things to Consider

Just like we talked about with nails, there are different coatings and materials to consider for your project. Exterior screws are made of materials like stainless steel or coated in ways to protect them against the elements. Make sure you take this into consideration if you are building something that will be outdoors.

Secondly, there are different thicknesses of screws. Screws are sized by number starting with the smallest, #4 screws, and getting progressively larger as the number increases. Take a look at the following options when determining the proper size screw for your project.

• #4 – Designed for small crafts, jewelry boxes, attaching hinges, etc. Very light duty. Available in 3/8″ to 3/4″.
• #6 – Small crafts, hinges and drawer slides, children’s furniture, toys, light duty jigs and fixtures, etc. Light duty, available in 1/2″ to 1-1/2″
• #8 – General furniture construction, cabinets, light construction; good all purpose. From 5/8″ to 4″.
• #10 – General construction, heavy duty furniture, outdoor projects, decks, lawn furniture, boat building, etc. Available in 3/4″ to 4″.
• #12 – For heavy duty construction, hanging solid core doors, etc. Available in 3/4″ to 4″.

Now you should have a pretty good understanding of nails and screws for your next project. In the end, the success of your project depends largely on you choosing the right fastener for the job. So, next time don’t just reach for the nearest screw in the box. Find the one that will last as long as you need it to and do the work that you demand of it.