Drill Driver, Impact Driver or Impact Wrench?

These sit next to each other on a shelf, cost roughly similar money, and all turn something. The confusion is understandable and it is expensive: an impact wrench used on woodscrews rounds the heads off, and a drill driver used on a seized bolt stalls and cooks its own clutch.

Drill driver

The one to own if you own one. It drills — wood, steel, plastic, and with a hammer setting, brick — and it drives screws through an adjustable clutch that slips at a torque you choose. That clutch is the whole point: it is what stops you burying a screw through a cabinet door or snapping its head off.

Its limit is torque. A drill driver holds the fastener with steady rotation, so once resistance beats the motor, it simply stops.

Impact driver

Looks like a stubby drill and works completely differently. Inside is a hammer and anvil: when resistance rises, it starts striking rotationally, thousands of short blows a minute. Each blow moves the screw a fraction, so it drives a 150mm screw into a joist without the tool twisting in your hand — which is what a drill driver would do.

What it does not have is a clutch. It drives until you release the trigger, so it is wrong for anything delicate: cabinet hinges, thin sheet, small brass screws, anything where over-driving ruins the work.

It also takes hex bits, not a chuck, so it does not drill unless you buy hex drill bits.

Impact wrench

The same striking mechanism, several times the torque, and a square drive for sockets rather than a hex holder for bits. This is a nut-and-bolt tool: wheel nuts, structural bolts, scaffolding, anything seized.

The number that matters is nut-busting torque — undoing a seized nut takes far more than tightening it did. Be careful in the other direction too: a wrench that can undo a wheel nut can also stretch or shear a bolt you meant to keep. Anything that matters gets finished with a torque wrench.

Which one, by trade

• Electrician. Drill driver, ideally 12V for panels and ceilings. Weight beats torque in this work.
• Carpenter, furniture. Drill driver for the fine work, impact driver alongside it for the long screws. The clutch is not optional on visible work.
• Fabricator, structural. Impact wrench, plus a drill driver for everything else.
• Vehicle work. Impact wrench, and check the nut-busting figure against the wheel nuts you actually meet.
• General contractor, one tool. Drill driver. It is the one that does something in every situation.

Torque figures, and how to read them

Manufacturers quote maximum torque, which is a laboratory number reached under conditions your work will not reproduce. Two honest ways to use it: compare figures only between tools of the same type, and expect real work at roughly half the headline.

On a drill driver, the more useful number is the number of clutch settings — more settings means finer control over where it slips.

A note on batteries

Impact tools draw current in sharp bursts rather than steadily, which is hard on a small battery. A 2.0Ah pack will run an impact driver, but it will sag under each burst and will not last a shift. The battery guide has the detail; the short version is 4.0Ah for an impact driver and ProCORE for a wrench.

Mistakes worth avoiding

• Ordinary screwdriver bits in an impact tool. They shatter. Impact-rated bits are made to flex instead, and they cost very little more.
• Chrome sockets on an impact wrench. Hand sockets crack under impact. Impact sockets are the black ones, and the difference is safety, not finish.
• Tightening to the tool's limit. An impact wrench will happily take a bolt past its yield point. Nip with the wrench, finish with a torque wrench.
• Buying an impact driver as your only tool. It cannot drill and it cannot be gentle. It is a second tool, not a first one.

See what we stock or describe the job and we will suggest the machine that fits it. Prices include GST, with a proper tax invoice on every order.