In this post, I explain the difference between a drill and an impact driver, or just “driver”. How are they different and what do we use them for?
Below is a video that Ethan did on the subject. But hey, please Dear Reader, help an old man out and read this post. I put my own spin on things. History and stuff. Forget the video.
Here’s a link to a nice combo set:
First, let’s look at a closeup of each tool. Here’s a typical cordless drill. In this case, it’s a Dewalt 20v Max XR Cordless:
Confusingly, the tool above is called a drill/driver! I’m going to be calling this one the “drill”. More on that later. But here’s an example of what I’m talking about when I use the term “driver”–an impact driver:
They Look Pretty Much the Same
You’re right. They kind of look like each other. Both are cordless and accept 20 volt batteries. They both have a handle and a trigger. And a motor. That’s what confuses us. Here’s the obvious, visible difference:
The chuck is the part that holds the bit. The bit is what makes the hole or turns our fastener. Here’s a closer-up of our drill’s chuck:
Yeah, that looks familiar. Power drills have been around for a long time. We’ve all seen drills with front ends that look pretty much like this one does. On the other hand, this one looks weird:
What in the world? That thing shouldn’t even be called a chuck! But it is. It’s just a fundamentally different kind of chuck.
The Story of Drill Chuck
As far as we know, the first drill was invented over 30,000 years ago. By a caveman (could have been a cavewoman, but we’ll call it “Moe”). By happenstance, Moe found a very sharp, pointy stone. He pushed the sharp point against something, maybe leather from a woolly mammoth. Nothing much happened. Infuriated, he twisted the stone around and around, while cursing. The sharp stone quickly made a hole in the mammoth hide.
The drill had been invented! His forearm was the motor. The sharp stone was the bit. And his hand? It was Chuck.
And the cursing? Moe passed that down to future generations of sailors and carpenters.
Through the years, drills were improved. In the 1800s, the twist bit was invented. Here’s a photo of one (not the original one):
Why it’s called a twist bit is lost to history. Who knows, maybe it’s because the pointy end is kind of twisted.
But you see the problem, right? The thing is round! And, being made out of steel, it’s hard and slippery. Really hard to grip.
Luckily for us, someone invented the modern chuck. That one required a key, which we lost if it was not strapped to the tool. Where it could get in the way.
Then someone invented the more modern one that mostly looks like the one in my closer-up photo above. No key required.
How a Drill Chuck Works
This is really technical, so pay attention.
- Look at the picture.
- The silver pointy thing at the very front of the drill is actually three pieces, like jaws.
- When you turn the black sleeve behind it, the three things move apart. I always forget which direction you turn the sleeve. You’ll have to experiment. (Depending upon your model of drill, you may also need to hang onto the sleeve behind the black sleeve.)
- When the jaws are far enough apart, stick the dill bit in.
- Now turn the black sleeve the other way. No, the other way. If you are strong enough, the bit will stay where it’s supposed to. If not, ask your wife or kid for help.
- Now drive your screw into the hole you just made. Crap! Drill bits won’t turn screws. What to do?
Impact Drivers and the New Chuck
When I was a kid (no, I didn’t know Moe), I don’t think we had these impact driver things. Impact wrenches, yes. I remember walking past the neighbor’s garage and hearing him taking lug nuts of his car’s wheels. His impact wrench used compressed air and was really loud. Brrrrrrr! That’s how we knew he was there. Since he was there, we had to wait until later to sneak in to look at his calendars.
I’m getting off topic. In the 80s and 90s, I was doing a lot of framing and remodeling. I don’t think there were impact drivers, even then.
So how did we drive screws?
By hand. Have you ever driven, by hand, a long screw into wood? That’s how you get big forearms.
Then, someone came up with the idea of driver bits. Here are some from Bosch:
Remember when I told you that the front of our drill chuck has 3 jaws? Well, these driver bits have 6 sides on their bases (hex shaped). That means they can be easily gripped by our chuck’s jaws.
So, by switching bits, we could drill holes and drive screws, both while using the same drill.
Here’s the process I followed when I still worked for a living:
- First, I drill a screw hole, using a twist bit.
- I loosen the chuck.
- I take the drill bit out of the chuck and lay it down on my jobsite work surface..
- Being round, the bit rolls off said surface.
- I curse (remember, I was a carpenter then).
- Rooting around in the grass and sawdust, I find the drill bit and put it in my pocket so it won’t get lost again.
- I grab my Phillips hex bit and try to insert it into the chuck.
- The bit I drilled the hole with is 3/16″. My driver bit is 1/4″. So I have to use the black sleeve to open the jaws a bit.
- I insert the hex bit and tighten the chuck.
- I start to drive the screw.
- Since I’m not pressing hard enough, the Phillips bit cams out. It starts to grind out the Phillips pocket in the screw head.
- I press harder and continue driving the screw. Almost there!
- About a half an inch from being completely driven, the bit cams out again. The pocket in the screw head no longer looks like a plus sign (+). It now looks like a circle (o).
- I try backing the screw out. Since the pocket is now round, no dice.
- Now I’m really pi–, errr, irritated. I curse some more. Turning around, I realize the customer is standing right behind me. So I sheepishly apologize and root around in my tool bucket for my vice grips.
- I grab the screw head with the vice grips and back it out of the hole. (What actually happened was that the screw head broke off, but this list is getting too long. I’ll pretend that didn’t happen.)
- I drive another screw into the hole. All the way, this time. Yes!
- Time to drill my next hole. Now where is that 3/16″ twist bit??
Reader: “You’re going to talk about impact drivers at some point, right?”
Yes, yes I am. Sorry about the digression. The memory of that screw breaking…
It’s not just that we needed two drills back then. In fact, drilling holes worked pretty flawlessly. Driving those big screws was the problem.
Luckily, someone, probably a frustrated carpenter named Bosch, bailed us out. Bosch had used hammer drills before. (No, I’m not getting into that in this post. It’s already 1300 words long.) Bosch thought, “Vatt eef I combined ein drill und ein impact wrench?”
So he did. Here’s the basic idea:
1. The chuck was simplified a lot. After all, it just has to hold a hex bit. There’s a quick-release gizmo behind the hex part of the chuck. Just push the bit in. It locks pretty securely, so it won’t fall out if you turn the tool upside down. Then, just pull it out if you break it or need a different type of bit, like square-drive or Torx. The key is that the shape of the bit head changes, but the hex shaft is always the same.
2. Here’s the part that really makes it work: Instead of just spinning, the motor rapidly taps, or “impacts”, the back of the bit. You hear that Brrrrrrrrrr! sound. That’s how fast the thing is hammering. The combination of spinning and hammering greatly increases the driver’s ability to drive screws. Especially big ones.
3. Since they are a relatively recent invention, they are cordless. There may be corded versions, but I’ve never seen one.
Impact drivers are so useful, and have become so ubiquitous, that they are often sold in combo sets, like the one at the top of this post. You can have a drill with a twist bit it. And a driver with a hex bit in it. No more need for cursing. Right, carpenters? …..Right?
Hey, I don’t need to listen to that kind of abuse! I can just say:
Thanks for reading. I’m Ross James with The Honest Carpenter.
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