Torque Vs Speed

Torque Vs Speed — The Whole Truth Revealed

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It’s the question most frequently asked by newbie drill buyers — what the heck’s the difference between torque vs speed?

Many online reviewers either have no idea themselves, so they either skirt around the subject completely, or simply assume that you, the reader, fully understand the complexity of this engineering conundrum.

However, if you’re serious about purchasing the ultimate tool for your hole-boring projects — comprehending the difference between speed and torque is crucial. It’s the difference between owning a unit that effortlessly sails through your DIY or trade work — or one that is totally unsuitable for the job at hand.

Consider this your torque and speed 101 — lifting the veil on this mysterious subject, and permitting you to make a fully informed decision when choosing your new machine.

Torque and Speed Explained

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Before we get down to the detail of comparing these two metrics, it’s important to understand what each term refers to in the drilling arena.

The Drill Speed

Unsurprisingly, the speed of a drill refers to the rapidity at which the bit rotates — or more correctly, the rate at which the internal motor drives the chuck that houses the bit.

Measured in rpm (revolutions per minute), it can range anywhere from a relatively slow 250 rpm — typified by the ShopFox W1668 — through to an eye-watering 3500 rpm as demonstrated by the DeWalt DWD520.

Usually, brushless motors — being inherently lower on friction — deliver greater velocities from the same sized powerhouses of brushed motors. Although, these low-friction models do hit your pocket a little harder.

However, a common mistake many new-drillers-on-the-block make is to assume that faster is better — which is a flawed concept. Consider it akin to sex. For romantic bedroom sessions with your wife, you may opt for the slow and steady approach. For illicit liaisons with your wife’s best friend, fast and frantic action may be more appropriate.

In short, it’s about gauging the correct speed and intensity for the job in hand.

For dense materials such as metals and concrete, a modest drilling velocity is essential — too much speed and you run the risk of destroying the bit head or overloading the motor. For softer mediums and repetitive tasks such as driving screws into decking — a faster rpm will allow you to complete the project in a time-efficient manner.

It’s for this reason that drills designed for dense materials — such as the rotary Bosch RH328VC have an upper rapidity limit around 900 rpm. Compare that to a drill driver, like the Makita XT269M — focusing on timber screwdriving — has a speed of 2000 rpm.

The Torque

Consider torque as a crucial companion to speed — being the power that overcomes the forces fighting against your rotational velocity.

Your drill bit doesn’t effortlessly plow into your boring material through speed alone — factors such as the size of the drilling head, density and texture of your base medium, and the friction created in the chuck bearings are all barriers to a smooth cutting rotary action.

To allow the bit to effectively create holes, it needs brawn to conquer these different forms of resistance. And that power is known as the torque.

The torque output is typically measured in inch-pounds (in-lbs), foot-pounds (ft-lbs), or Newton Meters (Nm) — depending on the manufacturer. Machines that target dense mediums like concrete, such as the rotary Makita XRH04Z, or that need the grunt to drive large screws or bolts, exhibit high torque in excess of 500 inch-pounds. Those drills designed for soft materials, like the Black & Decker BDEDMT, deliver a more modest torque output of around 130 inch-pounds.

On most good quality units, both the torque and speed are selectable. Those with the greatest range of settings offering the most user-tailorable function and adaptability to the base material.

Therefore, it would be natural to assume that if you purchase a high-torque, high-speed drill with a broad spectrum of settings, you have a tool that can handle anything, right?

Unfortunately, like most things in life, it’s not that simple.

The Relationship Between Torque and Speed

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Here comes the science bit around the relation between torque and rpm. Stick with me, it’s short and sweet.

Power (hp) = Torque (Nm) x Speed (rpm)

The power of the motor is fixed — the only way it can be changed is by replacing the internal powerhouse. Therefore with that constant in mind — for the equation to balance — if speed increases, torque must decrease. And conversely, if you elevate the torque, speed has to reduce.

You can’t have it both ways.

Industry experts refer to this as the torque vs rpm curve or the torque speed trade-off.

Think of it like this.

A standard farm tractor and family automobile both share a common element — an engine size of around 2000 cc. However, despite this shared powerhouse, the car lacks the grunt to pull a plow, and the tractor will not travel at 80 mph on the freeway.

The manufacturers of these machines have created internal gearing that either focuses on grunt or speed. Not both.

Hence, coming back to drills, many models allow you to change this gearing yourself — such as the DeWalt DCD708C2, which boasts 15 settings. A quick turn of a dial can either crank up or step down the torque — and automatically adjust the speed.

That said, the upper limits of either torque or speed depend upon the drill’s intended use — those focusing on softer mediums will have higher top speeds, those models for dense materials will incorporate greater torque ceilings.