A reader wrote in, asking for advice about combination tap drills. This type of power tool accessory features a drilling tip and thread-cutting grooves all in a single too.
Usually, I associate combination tap drills with sheet metal or thinner plate stock.
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Jacob wrote:
I’m am looking into buying a set of drill and tap combination drill bits. Do you think this is a good idea? Would it be better to buy a thread tapping kit, and just drill with normal drill bits.
I have been thinking of how to answer Jacob’s question, but there’s no right answer.
How do Combination Tap Drills Work?
Here’s a quick video demo of the Dewalt tap drills from a past media event:
Combination Tap Drill Pros
No tool changes are needed.
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No specialty-sized drill bits are needed.
No tap wrenches or other accessories are needed, just a cordless drill or impact driver (if impact-rated).
Combination Tap Drill Cons
Can only be used in thinner materials.
One-size-fits-all means you cannot cater drill size to the material or application.
I’ve seen some complaints about breakage.
Workpiece Recommendations
Some manufacturers advise that you can use tap drills in most commonly tapped metal materials up to 2X as thick as the desired threaded hole diameter.
ToolGuyd Preferences
Combination tap drills seem convenient for portable tool kits when you might come across a quick task that would otherwise require a hefty tap and drill kit.
Personally, I don’t use these for my regular thread-tapping tasks, I use separate drill bits and hand or spiral taps.
It seems to me that combination tools are better suited for certain construction or repair tasks, but I prefer standalone tools for fabrication-type work.
This is one of those questions that I find difficult to answer without knowing more. I would rather have a tap and drill bit set first, and then pick up a combination tap and drill set later if the needed presented itself.
For that matter, I like having plug, bottoming, taper, and spiral taps in the sizes I use most often, as well as a couple of common tap drill bit sizes, plus a full set of wire gauge and lettered drill bits in case I need to deviate in certain materials. Having wire gauge and lettered drill bits also come in handy for drilling different sizes of clearance holes.
Irwin sent over a Hanson tap and die set a few years ago, and although I have used it a bit, I still have a very firm preference when it comes to drill bits and hand taps.
The thing is, good taps and drill bits can get pricey. An all-in-one repair set comes in handy for those times when I’m not sure what I’ll need, and when I run into a situation where my on-hand tooling doesn’t cover all the sizes I need.
A combination tap drill set can be an interesting first choice, but its suitability absolutely depends on user intent.
For added benefit, many combination tap drills can drill, tap, and also countersink in a single operation. If the accessories fit the workpiece dimensions, it’s hard to beat the one-step operation they allow for. Separate tools and accessories would take a lot longer to achieve similar results.
BUT, use a tap drill improperly and it could break on you. This can happen to any hand or power tap, but it seems like it might happen more with this type of accessory.
I also feel that combination tap drills might not be as precise compared to using separate tools. It of course requires different machinery or accessories, but I can drill and tap holes much closer to a perfect 90° with separate tooling than I can with a tap drill in a handheld cordless drill or impact driver.
Whether tap drills could or should be used depends on the task. If it helps, consider how individual screwdrivers might be needed for tasks where multi-bit driver tips simply don’t fit.
Here’s what I would buy if I was set on combination tap drills:
Greenlee Set via Amazon
Dewalt Set via Amazon
Other Brands via Amazon
What’s your take on this type of accessory? Did I miss any pros or cons?
Update: Yes, these are available in metric sizes as well. Here’s our follow-up post on metric combination tap drills.
Mopar4wd
The greenlee set is pretty good I’ve used one quite a bit. For sure stick to thinner sheet metal. I have also found they work well in aluminum.
Chris Gutierrez
I have the dewalt units in standard and metric in my commonly used sizes. For automotive fabrication they are great and they save a ton of time.
I am always concerned about breakage but have been lucky so far.
When nealy every fastener is m6, m8, 1/4-20 it’s just so much more convenient than separates. I keep the full sets of separates in the drawer for other sizes or when I need to bottom something out.
Marco
I have the Dewalt’s in metric and standard sizes. Excellent quality and never have had an issue with them. When I worked for a large GC I used them on 100s of commercial steel doors for various hardware accessories. Closures, panic bars etc.
frampton
These look interesting. I usually only need a tap & die rarely and almost always on the fly.
Shane
I swear by these! I’ve only used the yellow and red brand and the performance of both are on par with each other. I drill in 1/8” to 1/4” aluminum and they work great for that. Steel…..not so much. My M12 surge will snap these easily when I’ve pushed them to the limit so I usually reach for a hand tap for steel.
Leonard
I’ve tried them and not a fan.
Maybe if you need one or two threaded holes but it is just to easy to get them off axis and break the tap.
MattW.
Had a spacer to extend a clutch puller for a snow mobile long story short it got lodged 6 inches deep into the engine what to do…… Used a Milwaukee drill tap 1/4 20, threaded rod and a slide hammer to pull it out. This same drill tap is on its 70ish holes usually used with a m12 surge. The spacer was 3/8’s thick w1 tool steel so it wasn’t soft so the point of all this is that they got me out of alot of situations. From personal experience the Milwaukee ones are tough and dosent blink at gang boxes and adding things to metal storage shelves like coat hooks or cord loops. The biggest issue i can fault them is make sure you drill straight but thats user error.
MattW.
One note to add is the drill tap can go in places a tap can. I had to use a 12in extension in 5/8’s hole there’s no way anything more 1/4 in bit and extension would fit. Even beyond the rare occasion on a blind hole the time you save not having many tools to do the same thing is well worth it even if they only last sub 100 holes.
Chris S
These are absolutely great in the electrical field.
They work best when re-tapping a mud ring screw hole or the holes for panel cover screws.
I use my m12 and m18 surge on the 1 or 2 setting depending on the screw size and the results are fantastic. I eases through metal like butter and doesn’t hammer like a traditional impact so I’ve yet to break any bits with the surge.
We don’t use them in drills though, it’s to easy to over torque and snap one before you can stop yourself.
aerodawg
I don’t find them to be worth much except for very thin material. I deal with a lot of hardened tool steel though so that may be the differentiator…
fred
Looking at old inventory lists – we had both Greenlee and Champion brands of them in the remodeling business. I’m not sure that those crews knew what a regular hand tap even looked like. But – based on inventory dates – I think that they used/broke some of the smaller (like 6-32) ones quite a bit and/or didn’t find much use for the larger sizes (like 5/16 or 3/8). I suspect that they were generally used to clean up threaded holes that were crudded-up on old-work electrical boxes and the like.
I’m pretty sure that the fellow who ran our tool room at the fabrication shop never ordered any of these – but we sure went through lots of other drill bits and taps.
nate
I used to use them a lot, but I didn’t like them occasionally breaking off if they hit the end of their fatigue life and then having to dig them out. I prefer just drilling out the holes unless I’m taping a bunch of holes in something that I can get to the backside of if one breaks. drill bits are cheaper too.
Drew M
I’ll stick with my 3 piece Greenfield Tap and Die tap sets. At this point, I have most sizes in my bin. It has definitely taken several years to get there though.
Maybe I’m weird but I also very rarely break taps anymore and I even “power tap” hundreds of holes some times as small as M2.5 with a cordless drill.
( I will add though if you really do have a TON of small holes to tap, use Balax threadforming taps. They’re nearly unbreakable but the holes do have to be EXACTLY the right size. )
Peter Fox
I have a set of the Greenlee ones, they work ok. They are not good on thicker material and no good on blind holes.
What I use most often are drill bit adapters from Snappy Tools I can pick whatever style drills and taps I want and have the convenience of quick change that 1/4 shanks offer. I prefer short (screw machine) length drill bits and production grade spiral point taps. when I wear our or break the bits I can just change them out.
https://www.snappytools.com/product-category/drill-bit-adapters
https://www.mcmaster.com/drill-bits/drill-bit-shank-adapters-for-power-screwdrivers-and-impact-drivers/
Nathan
I was going to ask do people run these with an impactor or a drill. I could see wanting to use a drill more so than impact driver. so as to now hammer on them.
but then I could also see it binding up too. I’ve not tried them but I’m interested.
is there a specific technique for it?
MattW.
I use a m12 surge and works fine just don’t run them at max speed. I’ve heard people have bad luck with 1800+in lbs impacts so I just stick to the 12 volt and take my time at a low to medium speed. Have you ran a self drilling sheet metal screw at max speed and have it dull or burn up the tip? Treat them as such and you’ll be fine.
MM
I think the usefulness of these things highly depends on your exact application. Coming from a machining/metalworking background I think these things are nearly useless for that job: They are not particularly good quality–they’re on par with most “hardware store” taps and drills but they are nowhere near pro/industrial quality; they’re not even up to par with the more premium hardware/contractor brands like Greenlee, let alone the real stuff machinists use. The all-in-one design means you cannot tap to the bottom of a blind hole, and they are difficult to sharpen. They also don’t state the class of thread fit so that rules out their use on many parts. Finally, I don’t care for their flute design. If I am tapping through holes I greatly prefer gun-point taps that shoot the chips ahead of the tap rather than this type of spiral which pulls the chips back towards the tool. Gun points are easier to sharpen, less likely to break, and put less force on the tool because the chips are pushed ahead of it rather than being caught up between the flutes and the hole. Another disadvantage is that the drill diameter is fixed. I like to be able to adjust my tap drill diameter based on the material I am working in and the exact nature of the job. If the metal is unusually tough to tap and loads aren’t particularly high on the part I like to drill slightly oversize, and vice-versa.
On the other hand I could see how they would be super useful for many contractors, and also Auto/marine work where that kind of precision or durability isn’t required. If all you need to do is make and thread a thru hole in some relatively thin material and you don’t really care about the precision or the class of thread fit, etc, they could be handy time savers. I’ve had jobs where I’ve drilled and then power-tapped hundreds of 10-32 holes using a cordless drill for simple access covers for some machinery. I did it in two steps–drill first, then tap. These would have gotten those jobs done in half the time.
MM
I forgot to mention another major issue with these: You can only tap relatively thin material. Once the material gets to the same thickness as the length of the drill bit in front of the tap threads you are limited. A standard tap, excluding tiny sizes, can be run more than its full depth into a hole–so long as there is still shank for you to hold with the tap wrench (or chuck if you’re power-tapping) you’re good to go.
Jared
These are neat, but I can’t imagine using them often. When I’m taping (tapping?) I usually want to be pretty precise and I just don’t see how these would be compatible with that. Plus the extra length of the drill portion below the tap area would get in the way for many of my projects.
I’m sure there are times I would use them if I had them though. It would be handy to have the drill bits sized for the tap all built into one and operable with power tools.
If I didn’t already have regular taps would I buy these as my only version? No way. Much too limiting unless I was doing repeated-fabrication-type tasks.
Do these come in metric? I almost never use anything but metric.
Stuart
Yes, they do come in metric!
https://toolguyd.com/metric-combination-tap-drills/
Jared
Nice! You’re the best Stuart.
Matt
I’ve always kind of scratched my head on these but I think that’s because most of my threading applications (few and far between) are in thick steel. Reading the article and the comments one application where I think these would really shine would be re-threading thin sheet material at one size bigger. Electrical or HVAC access panels being a perfect example. The crude solution is to Mongo-power an oversized or self-tapping screw in a stripped hole but if you wanted to do right and do it fast, these look like a great option. Light fixtures are another one where quickly going from like 6-32 to 8-32 could be handy.
Bill
I keep getting this error when I try to post a comment: Not found, error 404
Stuart
That means you angered the spam filter, and they were denying your comment access.
This happens rarely, and there’s no indication as to why.
The best course of action is to go back if you can, copy your comment text, post a placeholder (even just saying “placeholder”) and then email me your comment text directly or via the contact-us form linked-to in the bottom menu.
Certain word combinations trigger the spam filter, and when this happens there’s no easy way to determine which ones or why. The only option is top edit the comment through the back-end and paste in the desired comment.
The spam filter maker itself doesn’t know what part of any particular comment might cause it to be blocked, and it doesn’t happen enough for any patterns to become apparent.
It’s bizarre and frustrating, and without any known resolution.
Sasquatch Electric
As an electrician I use these all the time. I have probably 300-400 holes on the same 6-32 tap into back panels with the ideal set. I think the ideal are head and shoulders above the others I have used, maybe I just got a good set I’m not sure. The only issue I have is I burned a tip on a 1/4-20 tap and one of the 8-32 taps. Tried to go too fast into some really tough stainless, so you’ll have the. The only advice I have is to use cutting wax, it seems to make all of my consumables last forever.
Jacob
Thank you Stuart. This is very helpful. I think I’ll go with a seperate tap set, just because it seems easier not to mess up.
Paul
I like the idea. I’ve tried just about everything when it comes to tap adapters/wrenches and nothing works well. But taps last a really long time, drills not so much.
Doc John
Isnt one supposed to utilize some type of cutting lubricant?
Stuart
Usually, depends on material. Follow manufacturer guidelines.
Travis
I agree with the comments regarding these bits inferiority to machinist gradetaps ( Emuge TiN coated taps are hard to beat) but I have been using these lately in 3d printed parts, and they work very well for this purpose. Wouldn’t even try these in steel.
Brad Justinen
STOP THAT. Just because it has a hex drive doesn’t mean it should be run in a impact driver. Never ever should an impact driver EVER be used for drilling or tapping metal. Use a drill and use the clutch.
Stuart
That was a Dewalt demo station at a Dewalt media event where they were showing off their new impact-rated tap drills.
You’re right in that not all hex-shank tools or tap drills are impact-rated, but those were.
Robert Adkins
These will only tap thin metal, most of which probably shouldn’t be tapped anyway. I like to thread 1.5X deeper than the thread diameter. I have a set and find them useful only for bush fixes.
DG
Hi all, long time reader, first time poster. As to these drill-taps, I use them a lot. The cheap ones, from HF. At first i had issues with the smaller ones (m3-m4, and the like) breaking, I’ve tried everything, until I figured out a strange solution. 2 words: impact driver. Strangely, I can go as carefully and steady as possible with a hand drill, and I’d still end up breaking one. Hammer it in with an impact- goes in and out, like it’s going through butter. Even the cheap HF ones last a long time and stay sharp.
It’s not all unicorns and rainbows though. The biggest problem is tapping a non-through hole. That drilling tip means that a good 5-6mm at the bottom of the hole don’t get threaded. But, I have a regular tap set for those
Stuart
Thanks for sharing! I might need to try that. I’d think that the hard taps would be more likely to break with an impact driver given the stresses involved.
There are bottoming taps meant for powered use, although I don’t believe any are impact-rated or even equipped with a hex shaft for use with an impact driver.
DG
@Stuart, the ones I’ve been using aren’t impact-rated, just regular HSS. And I think that it’s the binding and twisting that breaks them, as to be expected from a hand drill. All it takes is a wee bit of limp-wristing it. Maybe, there’s something about the hammers spinning and banging inside the impact directly opposite one another that allows for a straight shot? I don’t know, it just works. Oh, lubricant is pretty important too. I just use wd40, or whatever other gooey slippery stuff is nearby.
MM
I’ve done a lot of power tapping with hand drills and I think it’s pretty easy to break a small tap that way because the average cordless drill today is fairly large and heavy, it doesn’t take much unexpected movement of that large mass to break a small tap, especially something as small as an M3. But most impact drivers are much smaller/lighter than a drill. They also have the handle much closer to the nose of the tool giving more control. The combination of lighter weight and better control makes it less likely to break taps. Also the small amount of slop in the hex drive can help as well–it lets the tool move a little without bending the tap.
There are power tools especially made for tapping. They’re basically a drill which has two special features:
1) it automatically reverses when you pull back on the tool
2) it has a special chuck to hold the tap. The chuck has special jaws to grab the square shank of the tap but it also has a bit of a swivel built into it so if you aren’t holding it perfectly straight it will give a little rather than breaking the tap
I used to have a Bosch GGW-10-E like this.
DG
@MM, that’s very cool, I never knew something like that existed! Which means, chances are that there are also aftermarket chucks like that, to bolt to an existing drill. Thank you for that info, I’ll look into that.
MM
@DG
There are special tapping chucks like that which can be mounted to a tool. The ones I am familiar with are meant to be used on drill presses and milling machines. If you do an internet search for “automatic tapping head” you will find them. Tapmatic is a well known brand. I don’t know if anyone makes them for handheld tools or not.
DG
@MM, @Stuart, apparently, Metabo (the “proper” one, not the Hitachi) has something to say about the subject with their GB 18 LtX BL Q1. May be worthy of a review?