Screws
Screws are a great way to assemble wood but there are many types and shapes. Screws are made of different materials and coatings that are designed for specific uses.
Parts of a Screw
- Drive - recessed shape designed to accept a tool that will turn the screw
- Head - wider than the shank and applies a clamping force to the top material
- Non-Threaded Shank - upper part of screw near the head that does not have threads so it can spin freely in the top material to allow for maximum clamping force
- Threaded Shank - contains the treads that actually pull the screw into the bottom material when twisted
- Threads - can be right handed or left handed
- Tip - generally tapers to a point but can be blunt. Can be self taping.
Additional Screw Attributes
- Thread Pitch
- Thread Length
- Overall Length
- Major Diameter
- Minor Diameter
- Crest
Screw Drive Types
- Hex (Allen)
- Slot (Straight)
- Phillips (Plus)
- Pozidriv (Plus with 45 degrees Indents)
- Torx
- Star
- Robertson (Square)
- Tamper Resistant / Security Drives
Screw Head Types
- Pan
- Truss
- Flat
- Fillister
Wood Screws
Wood screws have a distinct shape. A wood screw acts as a clamp and pulls the top piece of wood toward the bottom piece. The threads of a wood screw are spaced apart to reduce the chance of tearing out material. A wood screw should spin freely in the top piece to allow for maximum clamping force. Wood screws are strong but are brittle and should be avoided where movement of the pieces is expected.
Drywall Screws
Drywall screws should be used to attach drywall or gypsum board to building framing. Drywall Screws are very hard and brittle and therefore should not be used for wood assembly. Drywall screws are ubiquitous and are seemingly laying around everywhere. yYou will see many makers, professional and amateur, use drywall screws to assemble wood. You will likely do the same and in some cases in can make sense such as a temporary holding or when in a remote location and the only screws available are drywall screws.
Remember to have consistent and quality results you should use purpose designed wood screws to assemble wood and not drywall screws.
Pocket Hole Screws
Special type of screw that needs a jig to predrill the hole in order to insert the screw. The advantage of pocket hole screws is they can be used in butt joints and are hidden.
Lag Screws
Lag Screws are thicker heavier duty screws that can be used in structural applications.
How to Tell a Pozidriv from a Phillips?
Nails
Nails rely on tension and friction to hold wood together.
Bolts
Bolts can join thicker pieces of wood together and candy have great strength. Washers can help keep the bolt and nut from pulling into the softer than metal wood. Bolts should be sized based on the application and tighten to the proper torque.
Brackets
Brackets come in many premade sizes and configurations. An L bracket can reinforce a wood corner joint. A joist hanger is a specific bracket that reinforces framing members in building construction.