The ancient Greeks invented screws. They were not used for assembling things but, rather, for lifting water and crushing grapes. Pretty big screws. The Romans were the first to use screws for fastening. That use of screws soon disappeared from the Roman landscape, probably because each screw that was created required hand-filing of the grooves. Made that way today, each screw would cost about $50. Once the Romans decided that screws were too expensive, their use ended until about the time of Queen Elizabeth. Still expensive to manufacture, screws were used by the wealthy while the rest used nails and pegs.

We are all aware that modern technology has made nuts, bolts and screws affordable and available to everyone. Since threaded connectors of all kinds have far more holding power than nails, screws are becoming more common in everyday construction, including remodels.

Roof leaks, squeaky floors and drywall divots can be almost completely eliminated by using screws instead of nails. When nails that hold down roof sheathing pop up through the paper roofing underlayment, a leak can occur. Screws go in and stay in. When the floor joist dry out and the nails that hold the subfloor loosen, the floor will start to squeak. And nothing holds drywall tight longer than a drywall screw.

Screws aren't used for structural connections in home construction, but they are great for holding sheeting of all kinds. In the last few years screw guns have become automated. Plastic bands containing dozens of screws are fed through a driver tip that can firmly place a screw all the way into a 2x4 every second or so. Although a nail gun is faster, automated screw guns can drive screws completely home faster than the speediest carpenter can nail. Cabinets and furniture strength is improved every time a threaded connector is added.

There are many types of screw heads but four basic ones: flat, oval, round and pan head. The flat screw is normally used when the head has to be countersunk. Oval head screws are used in decorative applications. Part of the head is countersunk and part remains above the surface. Decorative washers are used with oval head screws to enhance their decorative value and to hold a larger surface. Roundhead screws are used where appearance is not important but where gripping power is. The deepest slot in a screw is found in the round head. The pan-head screw is used mostly for sheetmetal work. The head is flatter and broader than the others. Since the head normally can't be countersunk into metal, its flat profile makes for a cleaner finish. Because sheetmetal connections can be very thin, the threads of the pan-head screw go all the way to the head. That is why wood screws can't be used to hold sheetmetal connections. Screws have slotted heads and some have an X-shaped slot called a Phillips head. Another special type of head is the square slot. Of the three we have found that the square head can be tightened more securely than the others. However, for ease of use and availability, we use the Phillips-head type.

Wood screws have threads about two-thirds of the way up the shaft, the last third being smooth and larger in diameter than the threaded portion. You might assume that pre-drilling for a screw requires three drill bits: one for the tip, one for the shank and one for the head. This is sometimes the case, but a special bit is available that will drill all three holes in one fell swoop, It's called a countersink bit.

Sliding the screw threads over bee's wax will ease the job of driving the screw all the way home. Since most screws are made of brass or steel, it is important not to use soap as a lubricant. The soap's caustic compounds can cause the screw to eventually deteriorate.

Bolts are even stronger than screws. The slotted roundhead stove bolt is ideal for small jobs. Larger jobs that require a hefty connection are assembled with machine bolts. Here two wrenches can be used more forcefully than the screwdriver-wrench combination used to tighten a stove bolt. The combination round-square head of the carriage bolt is for decorative applications and in locations where security is required. For example, an exposed gate hinge can't be removed if it is installed with the carriage head exposed. The carriage head has no slots and the square section of the head is designed to interlock into a square hold in the hardware into which it is installed. The lag bolt is nothing more than a giant screw, but its holding power is great. Lag bolts can be used in wood or combined with lead lag shields to provide secure connections in concrete, stone and other masonry.

Dowels and nails often are useful, but a project assembled with threaded connectors is unsurpassed.