What an impact driver does, and when you need one
If you have ever leaned your whole body into a drill trying to sink a long screw into hardwood, watched the bit chew the head out, and finished the job with a burnt smell coming off the motor, the tool you wanted was an impact driver and not a bigger drill.
What it actually does
An impact driver looks like a short fat drill, and the difference is inside it. When the screw starts to resist, a weight inside the tool begins knocking the shaft round in rapid bursts rather than pushing against it in one steady twist. You get far more turning force at the screw head, and because the force arrives in pulses rather than as one long shove, almost none of it comes back up the handle into your wrist. That is the bit people notice first. A drill fighting a screw tries to spin you. An impact driver doesn't.
The two practical consequences are worth knowing before you buy one. It takes 1/4 inch hex shank bits and it has no chuck, so a round shank drill bit simply won't go in it. And it has no clutch worth speaking of, so it will keep going long after the screw is seated.
When it is the right tool
- Long screws into hardwood or seasoned framing timber, which is where a drill gives up.
- Batten screws and coach screws, where the alternative is a socket and a lot of ratcheting.
- Decking, where the job is a few hundred screws and the tool that tires you least wins.
- Rusted or seized bolts on an old trailer or shed, though for wheel nuts and anything big you want an impact wrench rather than a driver.
When it is the wrong one
This is the half nobody mentions when they are selling you one. An impact driver will snap the head clean off a small screw before you have registered what happened, and it will drive a screw straight through soft pine and out the other side of a thin batten. Anything delicate, anything into plasterboard, anything where the screw has to stop exactly flush, is a drill driver job with the clutch set. It also isn't a drill. You can get hex shank drill bits and spade bits, and they work, but for a clean accurate hole a drill is still the better tool.
Four things that make it work properly
- Use impact rated bits. A standard screwdriver bit is hardened to resist wear, not to absorb repeated shock, and it will shatter. Impact rated bits are made slightly softer on purpose so they twist instead of breaking.
- Start slow. Squeeze gently until the bit is seated in the head, then let it go. Most stripped heads happen in the first second.
- Let the tool do it. Pushing harder doesn't help and it pulls the bit out of the head. Steady pressure straight down the line of the screw is all it wants.
- Still pre-drill near an end. A long screw within 50mm or so of the end of a piece of hardwood will split it whatever tool you use, and an impact driver splits it faster.
Shop related products
- Katana 18V Cordless Impact Driver, bare tool. Runs the same Charge All battery as the rest of the Katana range.
- Katana 18V Cordless 1/2 inch Impact Wrench. The one for wheel nuts and seized bolts.
- Sutton SupaTorq Phillips PH2 bits, 50mm. The everyday size, and they are made for driving rather than for hand work.
- Toolking 208 piece power bit set. Covers hex, torx and square drive so you stop hunting for one odd bit.
More in power tools and fasteners and fixings.
Did you know we also stock galvanised 14g batten screws in store, in 50, 75, 100, 125 and 150mm, either singly or by the box, plus the stainless ones for anything outside. They aren't on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.
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Still learning, same as everyone, and happy to be corrected on any of it in the shop.
Cheers,
Candeece
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