Fasteners have evolved and expanded to meet growing needs and a multitude of applications. Bolts and screws by far make up the majority of fasteners. There will be times, however, when these are just too short or too small, and when their extensive use comes at a considerable cost. In cases like these, using threaded rods or studs can be your only option. They come in varying lengths and are easily cut to size. Versatility and low-cost makes threaded rods the to go-to fastener in the automotive, construction, plumbing, electrical and fabrication industries, among many others.
What are All Thread Rods?
In basic terms, threaded rods resemble very long threaded rods of screws. The threading is helical in structure and runs the whole length in the all-thread rod. This goes by several names but is essentially the same thing. You’ll hear of allthread studs, all thread rods, all thread, threaded bars or screw rods. There are also rods with partial threading of similar size.
All thread rods are used where there is the need for longer fasteners. The purpose is to fasten two items together, of the same or different materials. Allthread studs are commonly used in fastening wooden or metal objects together, in anchoring applications as well as in concrete or brick structures requiring additional strength. They can also be used with nuts or other fixings where needed. There is an all-thread rod sold in varying lengths, diameters (gauges) and weight loading capacity.
I’ve touched upon some of the uses of all thread studs. The threading along the entire length helps create a secure bond, and this is reinforced when tightened. Adding other fixings only increases holding strength. The benefit is that threaded rods can be used in many materials and applications, either as a permanent fixture, or can be removed when needed.
All-thread rod is also used in chemical anchoring in masonry, as pipe flange bolts, in pole lines as double arming bolts, and as inexpensive anchoring at greater depths. General usage is in automotive assembly and repair, manufacturing and production processes, shipbuilding, machinery and parts maintenance and more.
Types of Threaded Rod
Different designs lend to different uses and different characteristics. The most widespread is all thread rods or threaded bars, with threading run down the whole length. This is in right hand or clockwise direction. Nuts or other fasteners can be installed at any point along the thread.
Double-ended threaded rods have two segments of equal threading at either end and often include a smooth part in between that forms part of the fixturing point between the two items, Similar are tap-end studs that have threading that is longer in one end only.
A hollow threaded rod allows things like cabling or other parts to fit inside. These are inserted in openings at either end. Variations include those with external and internal threading.
Lastly, there are differences in threading pitch, or the distances between each thread. Rods with fine pitch have more strength as they bite more into the material. These are used in areas like automotive panels, and in aircraft and machine assembly. By contrast, all thread with coarse threading pitch is used in brittle materials, like plywood, SPF or OSB boards as well as in thinner gauged metals.
Materials and Other Considerations
Threaded rod variants are made from a range of materials. This depends on where the rod is used, the application, whether the rod is a permanent or temporary solution, and the required weight loading and holding strength. Most often you’ll see threaded rods made of mild steel and this is an adequate and cost-effective material choice for most uses. Stainless steel (in 306 and 314 grades) has slightly better strength, as well as heat and corrosion resistance, and is used in structural support, especially in concrete. Rods that are particularly affected from exposure to liquids are optioned with zinc-plating, or are hot-dip galvanised. Titanium rods are used in the oil and gas industry, aluminium rods in fabrication and machine assembly, and copper rods for HVAC purposes. All thread rod in brass or nylon is often sourced in smaller gauges, and used in light-duty anchoring.
Sizing is dependent on the application. All thread rod comes in either 1 or 3 metres in length. Individual rods can be connected together with coupling nuts to get even longer pieces. Gauges refer to the diameter in millimetres and this is denoted in M. This starts at 5mm (M5) and reaches 48mm (M48) in the thickest variants. The large sizes make all thread studs especially useful in heavy-duty applications. Rods can also be chosen based on the thread count (thread pitch) for the selected length. Rods with finer pitch and larger diameters and lengths will have the highest holding force.
Using Threaded Rod
The threaded rod is easily cut to the desired length. Neat, clean cuts are achieved with a powered or manually-operated rod cutter, but you can also use angle grinders and mitre saws with the correct attachments. The benefits are that a single piece can produce several fasteners, each with high tensile strength, good corrosion and chemical resistance and at a very affordable price point.