# Impact Wrench vs Impact Driver



## Bondo

Ayuh,... Other than tool attachment points, 'n the power available,..
They're essentially the same tool...


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## Know It ALL

*Need more POWER ?*

You are on the right track with Makita. I just had to share this since your profile somewhat fits mine. After hours of struggling with the large nuts and bolts on the many plows that I use I had to find some relief. I studied for hours on the best impact gun for around $200 and found the Ingersol Rand Thunder Gun. I took my time and landed this deal for $165 W/shipping. At the time the next cheapest deal was $205. This impact is loud and mean. I bought my smaller sockets <1 1/16 from amazon. I choose craftsman because of the warranty, the price and USA. The larger set that goes up to 2" is some china stuff. I could not afford a large impact set of USA impacts. 
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=360312779246&viewitem=&sspagename=STRK%3AMEWAX%3AIT


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## downunder

> My understanding is that they are very similar ...difference being the driver applies downward force in addition to rotational force whereas the wrench applies rotational force only.


So teach me something here. By downward force you mean from the tool and not from your pushing against the fasterner? It is my understanding that impact drivers/wrenches (both) use rotational force, somewhat like putting a wrench on a bolt and then hitting the other end of the wrench with a hammer to increase the turning force. Hammer drills (generally used for masonry work) use a hammering force like striking a chisel while turning at the same time. I have not heard of nor considered that either does both or am I misreading your post? Hmmmm!


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## piste

downunder said:


> So teach me something here. By downward force you mean from the tool and not from your pushing against the fasterner? It is my understanding that impact drivers/wrenches (both) use rotational force, somewhat like putting a wrench on a bolt and then hitting the other end of the wrench with a hammer to increase the turning force. Hammer drills (generally used for masonry work) use a hammering force like striking a chisel while turning at the same time. I have not heard of nor considered that either does both or am I misreading your post? Hmmmm!


yes from the tool. An impact wrench provides only rotational force/impacts whereas an impact driver provides downward force/impacts in addition to rotational force...the latter somewhat similar to a hammer drill. Wikipedia has a somewhat useful definition of the two. AFAIK impact drivers are not commonly used in automotive work...that's usually the domain of impact wrenches. Impact drivers are great for screws and such. But in most automotive work....you don't really need the driving component of an impact driver. In fact...again AFAIK...it would be undesirable in the situation where you are trying to remove a fairly tight bolt....because the impact driver ...even in reverse mode...will be applying the downward impact as well...whereas the impact wrench will only apply rotational force...a good thing for a bolt you are trying to remove. However an impact driver might be the better tool to remove a frozen screw as it would tend to keep the head seated and minimize likelihood of stripping the head.Whilst impact wrenches, impact drivers, and hammer drills...all have some degree of overlap in function...I'm trying to gain a finer sense of the similarities and applications...or lack thereof.


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## downunder

Well, shiver me timbers! I always thought that the impact drivers (the ones with the 1/4 inch collet that accepts screwdriver bits, etc.) were the same operation as impact wrenches, the only difference being the bits, sockets, etc that each used and the power.


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## whataboutj

What causes the downward force in the impact driver? I have been using my Dewalt impact driver for almost a year and have never noticed any downward force from the driver. anything other than the rotational force/impact is from either the screw pulling into the material or me pushing the driver.

With a hammer drill there is the "hammer" motion that delivers the "downward force"

This is new info to me on the impact driver-- I am curious to find out more info
J


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## downunder

From Wikipedia:
http://en.wikipedia.org/wiki/Impact_driver

An *impact driver* is a tool that delivers a strong, sudden rotational and downward force. In conjunction with toughened screwdriver bits and socket sets, they are often used by mechanics to loosen larger screws (bolts) and nuts that are corrosively "frozen" or over-torqued. The direction can also be reversed for situations where screws have to be tightened with torque greater than a screwdriver can reasonably provide.
 
A manual impact driver with screwdriver bits and adapters


Manual impact drivers consist of a heavy outer sleeve that surrounds an inner core that is splined to it. The spline is curved so that when the user strikes the outer sleeve with a hammer, its downward force works on the spline to produce turning force on the core and any socket or work bit attached to it. The tool translates the heavy rotational inertia of the sleeve to the lighter core to generate large amounts of torque. At the same time, the striking blow from the hammer forces the impact driver down into the screw reducing or eliminating cam out. This attribute is most beneficial for Philips screws which normally cam out as part of their design. It is less beneficial for flat head, also known as common, screws and is not beneficial at all for most other types.
 
Cordless motorized impact driver, battery, charger, and some bits


Another type of impact driver uses a motor to automatically deliver the downward and rotational forces. These have the advantage of greatly increased speed. They are most often used in construction and manufacturing to replace screwdrivers where speed and operator fatigue are an issue. In some situations however, this type falls short since current designs cannot deliver the heavy downward blow of a manual unit. This can be especially true on very stubborn fasteners.
These are not to be confused with the impact wrench, which is a motorized tool (usually powered by compressed air), with a similar name and function. These also use a hammering action to apply torque to fasteners. The difference is that impact wrenches do not provide the positive engagement that impact drivers offer as mentioned above. This is desirable though on hex head fasteners and others where the downward seating action is unnecessary and potentially damaging. To add to the confusion, they look identical to motorized impact drivers.
Buyers must also be aware that some tools improperly advertised as impact drivers are actually just impact wrenches. The only way to verify that a motorized impact driver is truly what it claims to be (without taking it apart) is to try it before purchasing.


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## KatHelms

*Powered Impact driver has NO downward force*



whataboutj said:


> What causes the downward force in the impact driver? I have been using my Dewalt impact driver for almost a year and have never noticed any downward force from the driverJ


I know this is an older thread, but I thought this should be cleared up a bit. It's mentioned at the end of the Wiki excerpt, but some people might not read that far...

A cordless/powered impact driver doesn't offer any downward-force. It is NOT like a hammer drill. This is a bit of misinformation that pops up now and then.

It's confusing because a manual impact driver - the one you hit with a hammer - certainly has that 'positive engagement' (i.e. the downward force into the fastener)

The cordless impact drivers work by creating a series of sharp and short impacts. The idea is that the torque is delivered so quickly, and is turned so little, the bit doesn't slip out of the screw.

As the wiki article points out - if there was a hammering-type action, you wouldn't want to use it on nuts with a socket when in fact this is one of it's best applications.

Pretty much, an impact driver is a small impact wrench, built with a chuck for a hex bit instead of an anvil for a socket.


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