Fast Talk - A Glossary Of Fasteners - Metal by the Metre

Fasteners may seem like a simple thing at first but you can quickly get overwhelmed by the names, types and styles of these beautiful little buggers. So we at Metal by the Metre have compiled a glossary to help get you sorted at your local metal supply store. 

Alloy Steel – steel that is alloyed (mixed) with other metals to improve its qualities. 

Aluminium – Aluminium is one of the most useful metals known to man. It can be alloyed with many other metals to improve their usefulness. It is strong, durable, impermeable, flexible, light, resistant to corrosion and recyclable. 

Anchor bolt – used to firmly hold down heavy objects such as timber frames, heavy machinery, and anchoring structural steel columns or beams into masonry. Concrete is pre-drilled and an anchor expands when tightened. E.g. Ramset Dynabolt.

Anchor screw – a high carbon screw used to anchor bottom plates into masonry. Unlike other concrete anchors the anchor screw doesn’t expand when tightened which avoids cracking of masonry. E.g. Ramset AnkaScrew 

Bihexagonal head – a screw or bolt head which is a 12 pointed star shape 

Binder head – similar to a pan head but with a deeper slot and much thicker shank. 

Bolt – a common fastener typically secured by a nut. The shank is not tapered like a screw. 

Brass – an alloy of copper and zinc. Very similar to bronze and a popular metal for decoration. 

Bugle head – refers to screws that have a side on profile similar to a trumpet or bugle. They are designed to sit flush with the surface material. Often confused with countersunk heads but not exactly the same. 

Bugle Batten screw – a heavy duty screw with a bugle (trumpet) shaped head. Bugles can replace coach bolts or screws in situations where a flush, countersunk finish is required. Commonly used in outdoor furniture or structures such as decks and gazebos. 

Button head –  has a rounded head with flat face. While it can have various drives, hex head versions are becoming more common.

Carbon – is alloyed to metals such as stainless steel to increase its strength but also increases its brittleness and susceptibility to corrosion. 

Chromium – the main ingredient in stainless steel that provides corrosion resistance. Adding 12% chromium to steel is how stainless steel is formed. 

Chemset – a version of anchoring that uses chemicals and an anchor bolt to fasten to masonry. Made by Ramset. 

Coach screws – heavy duty screw with thick shank used to fasten metal to timber or large timbers together. 

Connector nail – a nail used to fasten nail – on plates and joist hangers. 

Copper – a sort, malleable, reddish metal with high thermal and electrical conductivity. 

Countersunk – a conical hole cut into the surface of the material where a fastener will be placed. The countersunk cut will allow the fastener to be flush with the material. 

Cup head bolt – a bolt with a rounded head over a square neck to stop the bolt from spinning in its drill hole. Similar to a coach head bolt. 

Decking nail – heavy duty nails with a threaded shank either galvanised or stainless steel to guard against weather. 

Decking screw – countersunk head screws usually with square drive and made from 304 or 316 grade stainless steel. 

Dome nut – an aesthetic nut used to fasten material to a bolt. It has an enclosed dome head for a smooth, non- catching finish. Often made from stainless steel. 

Drive – the special shape design cut into the top of a screws head where a screw driver or bit connects. E.g. philips, slotted, torx (hex), pozidrive.

EM coating – a grey-green coating used to protect a screw against corrosion from treated wood. 

Flat washers – used to increase the surface area of the force applied by a tightened fastener. 

Internal drive – the polygonal shape in the head that a screwdriver attaches to. E.g. square, hex, torx, double square. Excludes slotted and phillips drives.

Molybdenum – the metal added to stainless steel that increases its corrosion resistance. This is the main difference between 304 grade stainless steel and 316 grade  stainless steel (316 having moly added)

Mudguard washers – similar to a flat washer but with a smaller diameter internal hole. Good for preventing smaller screws from pulling into soft timber. 

Needlepoint screw – one of the three main types of screw tips. Also known as thread forming. 

Pan head – flat top and face with rounded sides. Looks like an upside down frying pan without the handle.

Rib head – screw head with ribs underneath to assist countersinking. 

Shank –  the long, threaded body part of a screw or bolt. 

Shear strength – the maximum side to side strength of a fastener before it breaks.  

Socket head – an internal hex drive. 

Spring washer – a ring split at a point and bent into a helical pattern. (think water slide). Helps create more friction between nut and thread.  

Tensile strength – is the maximum pulling apart tension that can be applied to a fastener before it breaks. 

Thread – the raised ridge that winds around the body or shank of the screw or bolt. 

Torque or Torsion strength – is the maximum twisting or tightening that can be applied to a fastener before it breaks. A.K.A compression strength.