Can I Use an Impact Wrench as an Impact Driver? What a Hillman Fastener Order Taught Me

The request came at 4:22 on a Friday. Subject line: “NEED TOMORROW.”

I coordinate emergency supply orders for commercial contractors and repair crews. After six years and maybe 200 rush orders—maybe 230, I’d have to check our system—I’ve learned to read every line. This email was almost normal until the bottom:

Can I use impact wrench as impact driver? Mine just died and I have a 1/2-inch impact wrench on the truck.

My first thought was yes. I’ve used an impact wrench on hex-head lag screws before, and it will turn them. But “mine just died” usually means someone already grabbed the nearest tool and something went wrong. So I called before I answered.

When the foreman picked up, I skipped the stock check and asked a simple question.

“What size lag screw are you driving?”

“Quarter-inch. Hex zinc plated, three-inch.”

“Into what material?”

“Hardwood.”

That changed the answer. Two screws had already snapped before he made the call. His impact driver quit mid-row, someone handed him a 1/2-inch impact wrench, and two of the next few quarter-inch hex zinc plated lag screws twisted off before the bracket pulled tight.

The impact wrench is not an impact driver

The common question is whether an impact wrench can drive screws. The better question is whether it should. Both tools use impact energy, but they are tuned differently. An impact driver is built for screwdriving. It delivers smaller, quicker blows, so it can sink a long screw without hammering it the whole way. An impact wrench is built for sockets and high-torque fasteners. It delivers more energy per blow, which is great for a lug nut and hard on a small lag screw.

Inch-series hex head fasteners are made to fit standard socket sizes under references like ASME B18.2.1. That is why a quarter-inch hex lag screw takes a 7/16-inch socket rather than whatever bit is closest. The dimensional standard doesn’t tell you what tool to use, but it is a reminder that fasteners are designed to work with controlled force, not with unlimited impact energy.

So, can you use an impact wrench as an impact driver? You can, in the narrow sense that it will spin the fastener. The safer answer is: not if you want to avoid snapping more screws. If there is no other option, use the correct socket, set the tool to its lowest setting if it has one, and use short bursts. Stop the moment the screw head seats.

Every item on that order mattered

The order list itself looked simple:

• Hillman fender washer 1/4 in., 100 pieces
• Hillman anchor wire 18-gauge copper 25-ft., 2 rolls
• hex zinc plated lag screw, 80 pieces
• screwdriver sampler set, 1 each

It made sense once I understood the job. The Hillman fender washer 1/4 in. has a larger outside diameter than a standard flat washer. That wider face spreads the clamping force and keeps the head of a lag screw from pulling through a slotted bracket or oversized hole. It isn’t a filler item; it is the piece that protects the connection.

The Hillman anchor wire 18-gauge copper 25-ft. wasn’t part of the lag screw assembly. It was a separate inspection item for another crew on the same site. It still had to be on the same truck, and it reminded me not to assume the whole story fits in the first email.

The screwdriver sampler set looked unrelated until the foreman explained it. An apprentice had stripped two trim screws by reaching for the wrong driver bit. The sampler set lets them test which drive actually fits before they put power behind it. That small step would have saved more time than the expedited delivery.

Transparent quotes and honest tool answers

I sent the confirmation with the product total, the freight charge, and the Saturday delivery charge on separate lines. It was not the lowest quote he could have found that day. It was the real quote. No surprise fee appeared after he approved it. I’ve learned to ask what is not included before I ask what the price is, and I expect the same from vendors.

The same principle applies to fasteners and tools. The part you don’t think about is usually the part that costs you. A pilot hole. A correct washer. The right driver for the screw size. A lower bid with hidden fees will cost more in the end, and so will a tempting tool that is not built for the job.

The delivery arrived before 7 a.m. The crew made their window, and the invoice didn’t need a second email to explain it. That is the part I still think about when I see someone ask, “Can I use impact wrench as impact driver?” It can turn the fastener. The question is what it will cost when it keeps turning.