How to Put a Drill Bit into an Impact Driver: A Quality Inspector's Checklist

If you’ve ever stared at an impact driver and asked, “do I just push the bit in?” you’re not alone. I review tool kits for a living—200+ unique tool packages a year, and more line items than I care to count before they get sent to job sites. The question I get most often from newer contractors is about bit installation. So here’s the straightforward version, with the checks I use when I verify a new Makita setup.

What This Checklist Is For

This is for anyone setting up an impact driver for the first time, or for a crew lead who needs a standard process that all team members can follow. It’s not a brand comparison. It’s about getting the bit into the collet correctly, every time.

There are six checks. The third one is the one I see skipped most often, and it’s the one that actually matters.

Before You Start: Know What Fits

Impact drivers use a 1/4-inch hex collet. They don’t accept round-shank twist drill bits.

That’s the whole reason people get confused. The Makita DF347DWE drill—the one with the keyless chuck—takes round drill bits. The impact driver takes hex-shank bits. Different tools, different shanks. A round drill bit in an impact driver won’t lock in, and it’ll spin or slip as soon as you pull the trigger. Not ideal. Actually, not workable at all.

The 6-Step Bit Installation Checklist

1. Use the right bit shank. Look for a bit with a 1/4-inch hex shank. If the bit is round, you need a hex-shank drill bit or a 1/4-inch hex adapter. If the package says “impact rated,” that’s a good sign, but the hex shank is the actual requirement.
2. Clean the collet and bit shank. This is the step most people skip. Dust, grease, and old thread-lock residue can keep the locking balls from seating properly. Wipe the bit shank with a rag. Blow out the collet with compressed air if you have it. On a jobsite, that’s usually enough.
3. Pull the collet collar back. With one hand, pull the collar toward the rear of the tool. It travels only a few millimeters. Keep holding it while you insert the bit. If you don’t hold it back, the bit won’t slide all the way in.
4. Insert the bit until it clicks. Push the bit straight in. When it bottoms out, you should hear a click. Here’s something vendors won’t tell you: that click is not the bit locking. It’s the collar spring snapping back over the locking balls. If you don’t hear it, release the collar and try again.
5. Release the collar and test the lock. Let go of the collar. Then tug the bit firmly. If it slides out, reseat it. A properly seated bit won’t come out with moderate force. This tug test takes two seconds and prevents a flying-bit incident later.
6. Set direction and test on scrap. Flip the forward/reverse switch to forward, and give the trigger a quick squeeze on a piece of scrap. If the bit wobbles, stop. Wobble means the wrong shank, a worn collet, or a bit that didn’t seat fully. Fix it before you use it on a real workpiece.

If You Own a Makita DF347DWE Drill

If you already have a Makita DF347DWE drill, you know what a keyless chuck feels like. You close the jaws around a drill bit, tighten it, and go. The impact driver is a different system. It doesn’t close around the bit. It uses spring-loaded balls that drop into a divot on the bit’s hex shank.

That difference is why “just push it in” only works with the right shank. Use the DF347DWE for drilling holes and the impact driver for driving fasteners. They complement each other, but the bit mounting systems are not interchangeable.

If the collet on your impact driver gets worn or won’t hold bits, it’s a serviceable part. Makita has repair parts and accessories available separately. Replacing a collet is usually cheaper than replacing the whole tool.

A Quick Word About Jigsaw Blades and Tool Box Customizers

While we’re on the subject of bits that don’t belong in an impact driver, let’s talk about jigsaw blades. A Makita jigsaw uses T-shank blades. They don’t fit an impact driver. That seems obvious, but I’ve seen crews store jigsaw blades in the same tray as driver bits. Somehow, a T-shank blade ends up in someone’s collet. It never locks in correctly, and it wastes time.

If you use a tool box customizer—the foam insert system where you cut out exact slots—make distinct areas for drill bits, driver bits, and jigsaw blades. It takes an extra ten minutes to set up with this separation. On the job, it saves way more than ten minutes.

Common Mistakes That Show Up in Quality Checks

In our Q1 2024 quality audit, these issues showed up in about 18% of the kits we checked. The causes weren’t the tools. They were the connection between the tool and the bit.

• Round shank drill bits in a hex collet. This is the number one mistake.
• Bits inserted without pulling the collar back fully, so they were only sitting on the locking balls.
• Dirty bits with grease or paint residue that prevented a clean lock.
• Using regular drill bits in an impact driver for driving screws. They’re not built for impact torque.
• Mixing jigsaw blades and driver bits in the same organizer slot.
• Ignoring collet wear. If a bit has slipped once, check the collet before trusting it again.

One more thing I keep close: a 300mm pliers wrench. It’s not for every bit change. But when a bit or adapter is stuck in a dirty collet, a 300mm pliers wrench gives you the leverage to hold the collet or pull the bit without crushing the housing. If you have one in your tool box customizer, that’s the right time to use it.

A Note on “Impact Rated” Claims

Some bit packages say “impact rated” or “for impact drivers.” Per FTC advertising guidance, claims need to be truthful and not misleading (ftc.gov). That doesn’t mean every “impact rated” bit is perfect for every impact driver. I still check the 1/4-inch hex shank and test the bit on scrap before I put it in the box.

The Bottom Line

The bottom line: an impact driver is only as reliable as the connection between the bit and the collet. Most bit problems aren’t the tool. They’re the 30 seconds before the bit goes in.

Take the extra few seconds to clean, insert, click, and test. I’d rather spend 10 minutes explaining this now than deal with a mismatched setup later. An informed customer asks better questions, and a better question usually leads to a better tool purchase.