A few weeks ago, someone over at the Garage Journal forum asked about whether you can drill with an impact driver. The discussion then turned towards how much play there is in a 1/4″ hex chuck.
The short answer is that you can use hex-shank drill bits in an impact driver. But should you? Before I answer that, I must insist that you only use impact-rated drill bits in an impact driver. If you use regular bits and encounter enough resistance to engage the impact mechanism, there’s a high risk of potentially hazardous bit failure.
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So should you drill holes with an impact driver? Well, it depends on how precise your hole needs to be. For rough construction needs, such as boring a hole to pass wires through, then it should be fine to go ahead with the impact driver. But if precise hole placement, size, and roundness are crucial, then stick with a drill and regular drill bits.
It is worth pointing out that you can generally only find general purpose bits with 1/4″ hex shanks. Thus far I haven’t seen numbered or lettered bits with hex shanks, or specialty bits such as brad point or cobalt bits. That should also tell you something.
Do you have a different opinion? Please share it with us in a comment!
jeff_williams
An exception might be the spade bits with the screw tips. Once the screw tip is started, it won’t wobble. I use my impact (18v Dewalt) with them exclusively. Although the blowout on the other side from going so fast is huge. And spade bits aren’t exactly considered precision. Forsners are obviously a better choice.
James C
Would you mind making a video showing the process and results of drilling with an impact?
I’m not necessarily convinced by just looking at the chuck wobble. I’m no engineer, but I imagine there are two types of chuck wobble: One, with a standard three-jaw chuck that is damaged/defective to the extent that it still holds the bit securely, but doesn’t spin true. Two, with an impact’s hex chuck that doesn’t hold the bit securely, but does spin true.
Does that make sense (rather, am I explaining myself good enough, and does it make sense)?
Stuart
Jeff, you’re right, speed-spades might be an exception since they pull themselves through wood. I don’t recall ever seeing impact-rated spade bits, though.
Impact hole saws are awesome for drilling through sheet metal – that’s about the only exception to my general impact drilling avoidance.
James, I could try, but it might not be necessary. The size of the bit also makes a difference. The longer the bit, the greater the deflection. The effect is also exaggerated when using smaller bits.
Stuart
I didn’t record it, but I just drilled a series of holes with an impact driver and then drill.
1/2″ spade in wood – impact drilled slower, but there’s no discernible difference in hole size.
1/4″ twist bit in hardwood – they both drilled at about the same speed, with the impact hole being slightly wider and elongated. The difference isn’t huge, but noticeable. I repeated with another 2 holes, and the differences then varied from undetectable to slight.
It’s a very subjective call. Knowing that the deflection and potential for wobble is there, at least when starting holes or drilling through tougher materials, I can’t see myself using an impact to drill anything but rough holes. For rivet, fastener, or dowel pin placements, I recommend sticking with an ordinary drill.
fred
Maybe a cordless impact driver is not the preferred tool for drilling – but we certainly use larger sized (1/2 inch drive and larger) electric and pneumatic impact wrenches for drilling in poles, timbers and steel. The advantage is that the impact mechanism reduces any torque reaction when a knot or tough spot is encountered in wood – and on break-through in steel (e.g. a wide flange). In drilling poles – we generally use a car or ship auger bit and auxiliary chuck mounted on the impact gun. With steel we prefer using a magnetic drill press – but sometimes the set up doesn’t allow this – so we will resort to an impact wrench with an auxiliary chuck and twist drill. Anyway for precise steel drilling – when hole size and alignment (e.g. for bolt-up) are critical – undersized drilling and reaming (e.g. with a bridge reamer) to final dimensions is the way to go.
Harold
Aside from the issue regarding hole precision, I think that the average DIY-er should be most concerned about bit breakage, as you pointed out in the body of the post. Unfortunately, most won’t know the difference, or won’t care to pay the premium for impact-rated bits (which might sound like a marketing gimmick to someone who does not understand how impact drivers work).
Stuart
My stance is more against drilling with 1/4″ hex chucks, and impact drivers only by extension. I agree, that the reactionless torque is positively delightful when drilling large or deep holes. But with large or deep holes, you’re also going to want less slop and less vibration.
Although I have not used such a setup, I would also agree that an impact wrench plus aux drill chuck would provide great performance and results. I perhaps over-simplified things, focusing on 12V and even 18V impacts, rather than the entire broad spectrum of impact tools. But your pro usage and experience is also way beyond that of a typical homeowner or casual DIYer that might want to use whatever brand of reduced-shank 1/4″ bits they can find.
Harold, the same is true for impact sockets. If I had a nickel for every time someone smugly rejected my recommendation not to use regular chrome hand sockets with impact tools…
rob
I found out the hard way that even the “impact ready” bits aren’t really ready for impact use. I had to put some screws in and only had my 12v impact with me, so I figured what the heck it’s just a one hole I need to drill I’ll give it a shot. Well the bit broke off in the hole which made even more work for me to do, next time I’ll just bring both tools with me if I need to do drilling and driving.
jeff_williams
@rob – What brand of “impact ready” bits and what material where you working with? I’ve have abused the crap out of the DeWalt IR stuff (Thanks Stuart!) and have never had an issue.
Harold
@rob I’m with you and wouldn’t trust the IR drill bits either. A drill bit is really like a knife with a sharp edge. You wouldn’t take a hammer and hack away at the back of your knife if you were trying to cut through something. It would ruin the honed edge. The concept you want with a drill bit is more of a slicing motion, and an impact driver isn’t really designed to do slicing the way a standard drill is.
Now when it comes to hammer drills, this is a different story. You don’t really slice concrete or masonry, you want to “chip” away at it. This is also why masonry bits have carbide inserts (that aren’t very sharp, by the way) to hold up to the beating they get.
mnoswad1
I cant use anything but an impact driver when using spade bits.
Stuart
Which ones do you use?
mnoswad1
The impact driver works so well that there is really no other option. I use the bosch spade bits with the threaded tip/point. I think some other brands also have the threaded point now though. They really drive into the wood and draw themselves in without having to push on the driver (dewalt).
But this gist of the post about the wobble and lack of accuracy is spot on. You can’t use an impact for dowels or anything that requires precision. I am looking forward to using an impact drill bit in some 1/4 steel plate someday soon though.
DW
I haven’t done it a bunch but I like using my impact (Milwaukee 12v) for pilot holes. Having two machines set up to drill with different sized drills is often nice to have, without needing two redundant tools.
ToolRank Chris
I will let you decide for yourself if and when you want to use an impact driver to drill holes, but this is my experience.
I have been using impact drivers to drill holes from 1/16″ up to 3/8″ for the last 10 years as a finish carpenter, before “impact ready” bits were around. I have never had a problem with accuracy, and very very rarely do I break a bit. Keep your bits sharp and you wont have problems. For the most part, my regular drill only gets used when I need a hole saw or a specialty drill bit.
Just so you don’t think I am a hack, my resume includes finish millwork, bars, and cabinets at some of the top hotels, restaurants and resorts in California.
corey swaz
you can always buy the keyless chuck with the hex end on it, its a great item to have, i use it more then not in my field
Dr Abu Galib
I just bought a Hitachi DV13VSS impact drill(India). It seems regular drill bits should not be used, only impact ready ones. So what are the drill bit sets I can buy(woodworking only for now).
Stuart
If there is a selector to turn the impact function off, you can use it with regular drill bits. Otherwise, it depends on whether the impact action is rotary or vibratory as in a hammer drill. The product information I have looked up is unclear.
Brendan Donson
Why doesn’t anybody make a drill with an impact function? Equivalently, an impact driver with standard 3-jaw keyless chuck (and ability to turn off the impact function, and optional clutch and 2-speed transmission).
Then you could carry only one power tool instead of two, and the weight would be barely any greater than a regular drill. To use it frequently as just a driver, you can put a 1/4″ hex quick-change adapter in the chuck.
If you carry a drill and driver now just to be able to quickly alternate between drilling and driving without changing bits, you could still do the same with drills that have impact functions; just carry two of them. But for jobs where quick alternation isn’t required, you can carry just one, but still have both accurate drilling and impact driving (plus impact drilling, if you really want that).
Stuart
Combo-function tools tend to be larger and sometimes compromised in their performance.
An impact with a 3-jaw chuck might encourage the use of non-impact-rated bits, leading to lots of breakage and possibly performance issues. There are some drills with 1/4″ hex screwdriver chucks and quick-remove drill chucks.
Cory
I know this was a long time ago, but I am in search of a corded drill that has a 3-jaw chuck with a switch to toggle between impact and drill. They make many cordless versions with these exact features and they are not bulky at all! In fact, ridgid makes a cordless drill that has a switch to go between impact, drill, and hammer….and it has a keyless chuck.
uncaged
I’m thinking of using a hammer drill with a hole saw to install a deadbolt on my metal/wood door is this a bad Idea?
I only have a 12v dewalt drill and I doubt it would do the job.
Any suggestions?
Thanks
Stuart
It should be okay if there’s a rotary-only setting that turns the hammer function off. If there isn’t, then yes, it’s probably a bad idea.
uncaged
Thanks for the reply.
I was in a rush earlier and didn’t finish my thought. I have a 12v cordless drill that I know wouldn’t do the job so I bought a 18v hammer/driver that does have the option to turn off the hammer function. This is my first hammer drill drill so I wasn’t sure how they worked but I’m glad I picked it up. As a new home owner I have a ton of work to do around the house and I am sure the new drill will come in handy.
Take care
Stuart
It should be able to do the job then – good luck!
david
This may be an area in which the new oil pulse drivers would bridge the gap between drills and traditional hammer-and-anvil impact drivers. If a three-jaw chuck was ins talled on one, it seems like the longer “power pulse” would be nearly as smooth as a regular drill. I tried one of the Ridgid drivers in HD a couple of days ago and was impressed with how smoothly it drove a screw into (admittedly soft) wood. That may simplify Santa’s choice for me this year.
rick
How do you drill holes in reinforced concrete then? All the outside walls in my house are, so far, un-drill-able. I can’t hang or mount anything on any of them. Considering adding an interior wall for better insulation and also for an excuse to hang drywall.
Stuart
Hammer drill or rotary hanmer.
David
Impact driver great for marking holes in masonry using a smaller bit than your drill bit ie. using through bracket holes but hammer drill far more effective at drilling
Bernard
An Irwin 25mm 3 cutting faces auger when used in a Hitachi Impact Driver to drill into 2×4 wood failed. Initially when the load was low it spun and made a hole. Once the hammer action started the cutting edges rapidly lost their ability to cut the wood.
The auger had the 1/4 inch hex shaft so mated OK with the chuck.
Solution – use a rotary drill to drive the auger.
Dylan
What if you are using a drill press attachment such as the rockler portable drill guide. I do pegboards with the drill press attachment/forstner bit through hard plywood and my drill struggles with power. If the argument is that a drill would be or precise, but you are using a guide that keeps you steady and at the 90 degree angle, I would think a powerful impact with 1/4 chuck adapter would be fine, but what are your thoughts?