Fixings and fastenings

Machine screws are used to attach metal hardware ie flying irons, grummets, ceiling plates, ring plates, boss plates and in some cases pelmet clips to flats and scenery. Because they penetrate through the wood/metal and are secured with a washer and nut, they are a stronger fixing than screws. They have a countersunk head, which allows them to sit flush into timber or countersunk recesses on hardware.

Wire nails are an all round general purpose nail. They have a flat head that helps give a good hold.

Lost head nails can be either round or oval in section they are also referred to as brads in industry. The reason for the small head is so that it can be punched below the surface of the wood with a nail punch. The hole can then be filled with wood filler, leaving no visible marks.

Possidrive screws are probably the most commonly used screws in carpentry due to their ability to be driven by a screw gun.They have superceded slot head screws which are more problematic to use when using a screw gun.

Self tapping screws are designed to fix to steel. They are similar in appearence to woodscrews but are made of a harder material which is capable of cutting a thread (tapping) into a pilot hole in certain types of steel. The thread usually runs the full lenght of the screw.

Annular ring nails have rings/ridges around the shank to increase their grip in the wood. They are used where extra grip is required.

Star dowels are used to secure half laps and mortise and tenon joints and are a replacement for the more traditional timber dowel (shoe lace).

Coach bolts are used to fix, wood-to-wood or metal. The square section at the top of the shank and below the domed head stops the bolt from turning when the nut is being tightened. They are referred to sometimes in industry as dome bolts.

Hex bolts are usually used for fixing, metal to metal or metal to wood.They are often used for bolting steel deck together.

Coach screws are used for fixing, wood to wood, metal to wood. They are especially useful for fixing to the stage when a strong fixing is required.

Hex nuts fit onto machine screws, coach bolts and hex bolts. If they are being tightened up to timber then a washer should be used. Nylock hex nuts can be used if the item being bolted is to be used over a long period of time or if it will be subject to a lot of movement.

All the fixings referred to above come in various gauges and lengths. Nails are referred to by there length and head shape i.e. a 50mm wire nail. The bolts are referred to by their gauge, length and type i.e. an M10 X 50mm coach bolt. This is similar to how you describe screws.

Bolt plates are fitted onto timber where coach bolts are repeatedly re-using the same hole. They are mainly used on touring sets where the flats and scenery are constantly being assembled and disassembled. Basically they reinforce the square hole that stops the bolt from spinning when the nut is being tightened.