The Ultimate Screw Guide
In this guide, you'll discover details about the various screws we offer, plus more. While it's not a complete history of screws, we've gathered essential information on many screw types you might encounter while building cabinets or furniture. This will help you choose the best screws for your project. If you have any questions or need assistance, our team is available to help you become a Hero at Home. Call us at (800) 383-0130, Monday through Friday, from 8am to 5pm CST.
The Basic Anatomy of a Screw
Terminology
Cam Out
- Cam out is when your driver slips out of the screw head.
- Repeatedly camming out is what causes a screw to strip.
- Nearly every single innovation in screw design had the objective of reducing cam out.
Overdriving
- Overdriving is when you drive the screw in too far.
- This can reduce the force needed to pull out a screw by up to 20%.
- Increases risk of stripping the head or even the threads.
- Worst case scenario you split your material, which is more common on softwoods and softer hardwoods.
- You can avoid overdriving by getting to know the slip clutch on your drill/driver, or just take it easy if you’re driving by hand.
Countersink or Counterbore
- A canonical hole that is bored into the top of a screw hole for the purpose of allowing the screw to sit flush with or below the surface of the material it’s being driven into.
- Countersink is also the name of the bit used to cut such a hole.
Torque
- The rotational force applied to a screw or any rotating object.
- Applying too much torque leads to cam out.
- The slip clutch on your drill limits how much torque can be applied to a fastener.
Screw Heads
A thorough screw guide must include an examination of the diverse screw head options at your disposal. The head, which is the broad end opposite the tip as shown in the image, varies by design, each with its own benefits and drawbacks. Certain tasks necessitate specific head types due to their unique properties.
Pan Head
- These types of screws have flat bearing surfaces under the heads.
- Most common type of rounded-top screw head.
- Rounded head prevents catching things on it, and makes it suitable for decorative use.
- Enables a deeper drive socket for high torque applications.
- Can be found in almost any material/finish, size, or drive type needed.
Oval Head
- Very similar to pan heads and truss heads.
- Designed for use in countersunk holes to sit flush with the surface of your work.
- Has a round, raised decorative head.
Truss Head
- Common alternative for pan head screws.
- Sometimes called a mushroom head screw.
- Offers a larger, flat bearing surface compared to pan heads.
- Commonly used in decorative applications.
- Can be found in almost any material/finish, size, or drive type needed.
Flat Head
- These types of screws have a countersunk design.
- Some have self countersinking nibs so you don’t have to pre-countersink your holes.
- Can be concealed with adhesive or press fit cover caps.
- Can be found in almost any material/finish, size, or drive type needed.
Hex Head
- Hex head screws have a six-sided head for use with sockets and wrenches.
- Generally found on lag bolts or other fasteners for very heavy duty applications.
Washer Head
- Has a built-in washer to increase bearing surface area and prevent overdriving in softwoods.
- Very popular in furniture making and cabinetry, commonly used to mount cabinets in place.
- Very common for pocket hole joinery.
Trim Head
- Trim head, or finish head screws have as small of a head as possible for minimum visibility and concealability.
- People commonly use these types of screws for decorative molding and trim.
Drive Types
Examining the drive types available on various screws is crucial. While personal preference often guides your choice, security considerations can dictate the use of specific tamper-resistant drives. It's key to understand that many so-called 'tamper-proof' drives are only secure because they are uncommon. With the right tool, these screws lose their 'tamper-proof' status.
Slot Drive
- The first screw drive ever developed and manufactured because it was the simplest and cheapest to produce.
- Still a common sight today in some manufactured parts and jewelry, though less so in DIY projects
Philips Drive
- These types of screws came to the market as an alternative to slot drive screws in the early 1900’s.
- Has a lower tendency to cam out, especially when using power tools, which were first rising to popularity when Philips drive was introduced.
- Very common for wood screws, and screws in general
Square Drive
- Originally called the Robertson drive after the inventor P. L. Robertson.
- A further reduction of cam out probability after the innovation of the Philips drive.
- The square recess on this type of screw is very slightly tapered making the insertion of the tool easier and tends to keep the screw on the driver without having to hold it.
- Very common for wood screws.
Star Drive
- Star drive is the generic name for Torx screws.
- Not to be confused with security torx, star drive look identical but they are missing the security pin in the middle.
- Star drive offers even greater improvements to cam out over square drive.
- Very common driver for wood screws.
Security Torx Drive
- The proprietary name for star drive screws; Kleenex is to tissues as Torx is to star drive.
- The term torx usually refers to security torx drive screws, which have a security pin in the middle of the screw head to prevent tampering or unauthorized removal, where typical star drive screws do not.
Pozi Drive
- Looks very similar to Philips drive, but there are identification tick marks set 45° from the main cross section.
- Patented in 1962, pozi drive was designed to allow more torque and greater engagement than Philips.
- DIYers often use these types of screws for drawer slides and hinges of European origin.
- You cannot use a pozi driver on a Philips drive screw, and you cannot use a Philips driver on a pozi drive screw.
SQUIPPS DRIVE
- This drive is a combination of Philips and square drive on one head.
- Enables you to use either a Philips or square head bits/drivers.
- Very common for wood screws.
- There also exists a dedicated driver tip for these, but we do not carry it, and it kind of defeats the purpose of using a combination drive head, being that you can use whatever driver is available at the moment.
Thread Features
Thread characteristics are something to pay attention to when looking at different types of screws. Generally speaking, if you drill a pilot hole and pay attention to your work, you shouldn’t worry too much about these specialty features until you’ve got some experience under your belt. These features can be quite nuanced, so let’s go over a few of them.
Self Tapping Threads
- Self tapping screws are a class of screw that forms their own threads into the material you put them into, grabbing into as much material as possible.
- You will generally see this advertised in the screw’s name or features list.
- There are two types of self tapping screws: threads cutting and thread forming.
Thread Cutting Screws
- A type of self tapping screw, thread cutting screws have cutting edges and chip cavities that create a mating thread by removing material from the hole.
- Creates a very tight, vibration resistant hold.
Thread Forming Screws
- Thread forming screws are similar to thread cutting screws, but instead of removing material to form threads, they displace material, pushing it out of the way.
- These types of screws form an exceptionally tight hold.
- Commonly used in plastics or softwoods.
Milling Ribs
- Sometimes referred to as CEE threads, knurled shoulder, under-head cutting ribs, or knurl.
- This is a small section of steep threading below the screw head, and above the normal threads.
- The purpose of these ribs is to enlarge the hole very slightly to allow an enlarged upper shank to sink into the material more easily.
Hi lo Threads
- Has two different sized threads on one screw.
- The high threads are sharper and taller than conventional threads, requiring less force to drive in.
- The low threads leave more material between the high threads, in combination with a thinner shaft than conventional screws, this makes these screws very resistant to pull-out and vibrational loosening effects.
- These types of screws are ideal for plastics or other soft materials.
These screws come in various combinations of the features we've discussed. Some are highly specialized for particular applications, while others serve more general purposes, but each one is designed with a specific function in mind.
Cabinet Screws
- While you can technically fasten down a cabinet with any kind of screw, cabinet shops typically use something with a wider bearing surface like a washer head.
- The best cabinet screws have a wider bearing surface under the head of the screw which gives the screw the holding power necessary to keep cabinets in place.
- The above example uses a star drive for reduced cam out.
- It’s got a self drilling tip so you don’t have to pre-drill a pilot hole.
- It's also got a flat washer head for supreme holding power.
- All of these features come together to give a screw that can be easily and quickly driven in while installing cabinets.
Pozi System Screws
- Also called euro screws, these types of screws use a pozi drive on a countersunk flat head, with a blunt tip.
- Designed for use in pre-drilled 32mm system holes for cabinets.
- Commonly used with drawer slides and hinges.
- Deep, aggressive threads for grabbing into MDF and hardwood.
Break-a-way Screws
- Break-a-way screws are commonly used for cabinet knobs and pulls.
- They have breakaway points every ¼”.
- If you’re working with a variety of material thicknesses or different knobs and pulls or if you’re unsure of the dimensions you’re going to be working with, rather than buying a bunch of different sized screws, you can buy break-a-way screws and snap each one off at the exact length you need.
Pocket Hole Screw
- You can use these types of screws in pocket holes.
- Pocket holes are a relatively new innovation in woodworking as a method for joining pieces of wood together.
- A hole is predrilled at an angle, usually 15°, and the screw is driven through both pieces.
- If the hole is positioned correctly, this can be a very discrete method of joinery.
- There are pocket hole plugs available to further conceal evidence of the screws in furniture or cabinets.
- Kreg Tool, the company that invented pocket hole joinery back in 1986, has a nice guide on how to choose the correct screw to use, which you can find here: https://learn.kregtool.com/learn/how-to-select-right-pocket-hole-screw/
Drill Point Screws
- A drill point is a small, fluted end on a screw designed for drilling into metal at the same time as driving the screw.
- Commonly used for securing things to metal studs without predrilling.
- It is crucial that the drilling section is longer than the thickness of the metal you are drilling into.
Sheetrock Screws
- You can use these types of screws for hanging sheetrock/drywall.
- Flat countersunk heads for a flush finish.
- Extra hardened to be able to get through sheetrock, but as a result of that extra hardness they are brittle, so they are susceptible to completely sheering off the head if too much torque is applied.
- This hardening process is what gives them their black color.
- NOT recommended for hanging cabinets.
Lag Bolts
- Very heavy duty fastener.
- Very thick, usually around ¼”, will require pre-drilling.
- Generally used in very demanding, high stress applications.
Confirmat Screws
- Primarily used in MDF or other particle boards.
- Commonly included in ready-to-assemble furniture, like what you might find at IKEA.
- Has a large shoulder under the head to lock the screw in and prevent it from being pulled through the material.
- These unique fasteners act like a steel dowel forming a strong, stiff butt joint.
Decorative Hinge Screws
- A series of Philips drive screws with various head types and finishes to match Amerock decorative hinges.
- Aesthetics are a large part of the use case here.
8-32 Screws
- These types of screws adhere to the machine screw industry Numeric Size System.
- ‘8’ represents a size 8 diameter, which is 0.1640 or 41/250 of an inch.
- ‘32’ represents the threads per inch, which is 32.