The 9 Best Digital Torque Wrenches
This wiki has been updated 18 times since it was first published in December of 2016. When you're working with automotive or industrial equipment, precision and consistency are of utmost importance, so one of these digital torque wrenches will be an excellent addition to your arsenal of tools. Offering accuracy and easy-to-read displays, they are designed to let you know when your target amount of force is achieved, to help prevent overtightening and damaging a nut or bolt. When users buy our independently chosen editorial choices, we may earn commissions to help fund the Wiki. Skip to the best digital torque wrench on Amazon.
Quinn Digital Torque Wrench This selection, available from Harbor Freight Tools, features a half-inch drive and an easy-to-read LCD screen that displays up to five different units of measurement. It’s made of heavy-duty hardened steel, with a polished chrome finish, and delivers a torque range of 12.5 to 250 foot-pounds. With the touch of a few buttons, you can program and store up to nine preset torque ratings. Sound and light alerts indicate when your desired setting is reached. It comes in a protective molded case for organized storage and convenient transportation. harborfreight.com
July 08, 2019:
The GearWrench 85077 comes on board as a reliable means of ensuring the proper level of torque by way of vibrating, buzzing, and an indicator light. It’s well-suited for auto mechanics, thanks to its oil- and solvent-resistant handle and housing. Available in either a 3/8- or 1/2-inch drive size, it boats a comfortable handle and a slim design that’s similar in look and feel to an old-fashioned manual torque wrench. It’s from a company known for producing the original five-degree ratcheting wrench in the late 1990s.
Also joining the list is the Summit Tools WSP3-030CN, which offers a handy auto-shutoff feature, which helps to preserve its battery life. Its prominent LCD screen makes taking readings easy, and it can provide readings in newtons, pounds, and kilograms. Note that while its handle is comfortable, it is on the larger side, which isn’t ideal when you’re working in tight spaces.
Features to consider when you’re shopping for the right torque wrench include the drive size, stated accuracy rating, and an available torque range that fits your applications. You might prefer the convenience and accuracy afforded by a beam torque wrench, which uses a visual indicator to show the amount of torque weight applied as you tighten or loosen your fastener. Or, many feel that no tool box is complete without a standard, manual torque wrench, and various models have stood the test of time when it comes to accurate measurement, ease of use, and durability.
A Crash Course In Physics And Force
Combining the two results in a twisting force, known as torque, or moment of force.
Force, a classical concept at the root of all physics, is simply an interaction that alters an object's motion — which is an awfully broad definition. We observe forces like gravity on a massive scale, drawing planetary bodies toward and away from each other, while atomic nuclear forces hold together the materials that make up everything around us — and us, as well.
A force that sets an object in motion gives it what's called linear momentum, while one that alters an object's direction confers angular momentum. Combining the two results in a twisting force, known as torque, or moment of force. It's a snapshot of just how much rotational pressure a force is applying to an object at a given point in time.
Since the industrial revolution, humans have achieved incredible feats of engineering, building ever-more-powerful machines to aid in ever-increasing aspects of life. Industrial components were the first to demand modern structural engineering, and in 1918, an exceptionally clever NYC Water Department employee named Conrad Bahr invented the first torque wrench in order to prevent over-tightening of bolts on water mains and steam pipes. While metal certainly seems quite solid, it can be anything but that at high temperatures and pressures.
The contact surfaces on such parts are carefully machined so they fit perfectly together. When torque combines with the mechanical advantage of the screw (which, as an inclined plane wrapped around a cylinder, is likely the most complex simple machine of all), a tremendous amount of force can transfer to the opposing faces. The fasteners holding them together stretch ever so slightly to provide consistent clamping, but if the force applied exceeds a bolt's tensile strength, that bolt will stop stretching and, if it doesn't break straight away, start to compress the material it's supposed to be securing. Compression leads to warping, microfractures, and failed seals when it befalls pipe fittings, which is why Mr. Bahr was so invested in preventing it. The general public's familiarization with torque, however, started with the popularization of that wonderful machine: the automobile.
Chasing True Structural Integrity
Cars are the type of heavy machinery that's most readily available to the average citizen. Seeing widespread use for over 100 years and counting, these vehicles are the most prominent examples of torque in everyday life, and they're a prime target of the many types of torque wrenches now sold.
Cars are the type of heavy machinery that's most readily available to the average citizen.
The effectiveness of a combustion engine moving a huge vehicle depends on the strength and resilience of the drivetrain. Over-tightening critical bolts and warping the underlying structures damages the integrity of the metal, causing torsion, where an object physically twists under the influence of torque. This can lead to deepening cracks, an off-balance center of gravity, or even complete structural failure. For example, two extremely over-compressed lug nuts could throw off the wheel's rather delicate balance, and the resulting vibrations are liable to damage steering or suspension components, or shake other nuts right off their lugs — a bad thing for entirely obvious reasons. Additionally, over-torquing stretches bolts to their maximum, and their own reduced integrity could lead to shearing, which is another excellent way to lose a wheel on the freeway.
Underneath their hard exterior, of course, even cars have a sensitive side. The seals and gaskets that keep the life-bloods of coolant and lubricant contained are made of quite soft materials, designed to be replaceable while providing a perfect, high-pressure seal. It's considerably easier to compress a head gasket than a wheel hub, as gaskets are made from relatively soft composites of graphite or asbestos, and more recently copper — still a quite soft metal — reinforced by flexible alloy wires.
Additional applications for torque wrenches include pressed bearings, whose internal cages and retainers can suffer damage from excessive clamping force, causing them to fail. Belt-drive bushings also demand the perfect force, as the wrong amount can mean a misaligned belt, spinning cogs, or a snapped crankshaft. Warping and compression can compromise anodized and galvanized metals, as well, leading to hard-to-diagnose and potentially dangerous corrosion. Furthermore, critical medical equipment like halos and bone screws require exactly precise torque. The truth is, it's never good to over-tighten a fastener.
Types Of Torque-Sensing Tools
The simplest and most common variety consists of two beams connected at one end to a socket drive. The upper beam remains straight as you apply pressure and flex the main shaft, where a graduated scale displays the current level of applied torque. It has a relatively high load capacity, which is exceeded by its advanced cousin of the deflecting-beam variety. Other mechanical options use a spring-loaded roller-and-cam setup that slips when it hits a certain level of resistance, while another has an internal hinge secured by a small pawl gear that clicks out of place at the predetermined setting, signifying that it's reached the proper force.
It has a relatively high load capacity, which is exceeded by its advanced cousin of the deflecting-beam variety.
Most electronic models utilize a strain gauge, which consists of a metallic foil wire arranged in a close-knit pattern that, when bent, changes its electrical field. This change is relayed to a tiny computer chip inside the unit and displayed on an LED screen. Many allow you to record, recall, and compare readings, while advanced versions feature dynamic sensors that provide full-motion readouts and help engineers determine properties like breakaway torque and yield points, which are particularly useful in high-powered industrial and automotive applications.
There's variety within each type, and there are some important considerations such as water and oil resistance, grip material, and ergonomic handles. There are models with audible as well as haptic feedback, and a few are combinations of digital and click-type gauges. Longer wrenches are more precise, yet harder to fit into small spaces, though some have pivoting heads that help mitigate this. Like many tools, if you start with a reputable brand, take good care of it, and keep it calibrated, the right torque wrench should last for years, needing only a replacement battery every now and then.
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