# Hammer drill vs impact driver?
**URL:** https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952
**Category:** Factual Questions
**Created:** [April 28, 2013, 10:16pm UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952 "2013-04-28T22:16:18Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@Reply](https://boards.straightdope.com/u/Reply)
#### Post date: [April 28, 2013, 10:16pm UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/1 "2013-04-28T22:16:18Z")
I’m not entirely sure what the difference is, but a cursory reading leads me to believe that a hammer drill has a back-and-forth motion (like hammering in a nail) whereas the impact driver’s impacts are left-to-right (in line with the screw’s direction of rotation).
Is that a correct understanding?
---
### Author:  [@FuzzyOgre](https://boards.straightdope.com/u/FuzzyOgre)
#### Post date: [April 28, 2013, 10:43pm UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/2 "2013-04-28T22:43:40Z")
Yup.
The hammer drill spins while knocking at the material. It either chips it, or causes the bit to bite in. The impact driver is like putting a socket and wrench on a nut, and then tapping the wrench with a hammer. Neither one needs to apply much force: its death by 1000 taps.
---
### Author:  [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)
#### Post date: [April 28, 2013, 10:49pm UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/3 "2013-04-28T22:49:26Z")
Yes. They are also essentially two different tools. An impact is not normally used on screws, but nuts & bolts. The quintessential kind is used to remove car lug nuts. Also impact guns are most often driven by compressed air. A hammer drill is, well, a special type of drill. It has a standard drill bit chuck and is usually electrically powered (though large ones can be pneumatic) and adds a ‘hammering’ motion like you describe. These are often used for drilling into hard surfaces, namely concrete and masonry.
An electric screw gun is just a drill-type driver for putting in screws more fast & easily, but not into hard materials. It may have a clutch-slipping drive that engages when pushed against, but it doesn’t add any additional force other than rotational torque.
---
### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [April 28, 2013, 11:24pm UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/4 "2013-04-28T23:24:34Z")
Electric impact drivers, both AC and battery, are regularly used to drive deck and lag screws. A 3" wood screw will go in a lot faster with an impact driver than with a drill/driver. I use mine for wood screws larger than #8.
---
### Author:  [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)
#### Post date: [April 29, 2013, 12:08am UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/5 "2013-04-29T00:08:06Z")
> [@GaryM](#):
>
> Electric impact drivers, both AC and battery, are regularly used to drive deck and lag screws. A 3" wood screw will go in a lot faster with an impact driver than with a drill/driver. I use mine for wood screws larger than #8.
But are these actually called ‘impacts’? I always just called them screw guns. And given the way screws work I don’t think you’d \*want \*to add any pounding down-force to them, just torque.
---
### Author:  [@Melbourne](https://boards.straightdope.com/u/Melbourne)
#### Post date: [April 29, 2013, 12:19am UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/6 "2013-04-29T00:19:53Z")
> [@Reply](#):
>
> I’m not entirely sure what the difference is, but a cursory reading leads me to believe that a hammer drill has a back-and-forth motion (like hammering in a nail) whereas the impact driver’s impacts are left-to-right (in line with the screw’s direction of rotation).
>
> Is that a correct understanding?
My impact driver is driven by a mallet. My hammer drill has a special kind of slip clutch.
I wouldn’t use either term without clarification if it was important.
---
### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [April 29, 2013, 12:32am UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/7 "2013-04-29T00:32:57Z")
The impact drivers, not impact wrenches, have no downward force other than what you apply to keep the bit in the screw head. They will drive a screw much faster than a drill/driver. I’m talking about models made by Hitachi, Milwaukee, Bosch and the like.
[http://www.amazon.com/gp/aw/d/B000JEYJ1S](http://www.amazon.com/gp/aw/d/B000JEYJ1S)
---
### Author:  [@beowulff](https://boards.straightdope.com/u/beowulff)
#### Post date: [April 29, 2013, 12:40am UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/8 "2013-04-29T00:40:58Z")
Look at the guts [here](http://www.right-drill.com).
---
### Author:  [@Renee](https://boards.straightdope.com/u/Renee)
#### Post date: [April 29, 2013, 12:44am UTC](https://boards.straightdope.com/t/hammer-drill-vs-impact-driver/656952/9 "2013-04-29T00:44:12Z")
> [@Hail\_Ants](#):
>
> But are these actually called ‘impacts’? I always just called them screw guns. And given the way screws work I don’t think you’d \*want \*to add any pounding down-force to them, just torque.
We have this set: [Makita LXT211 18V LXT® Lithium-Ion Cordless 2-Pc. Combo Kit - Power Tool Combo Packs - Amazon.com](http://www.amazon.com/gp/aw/d/B001DN1T6M/ref=mp_s_a_1?qid=1367195890&sr=8-3&pi=SL75) which includes a hammer drill. The hammer drill Makes driving long screws into lumber extremely fast and easy. Best tools we’ve ever bought.