Toolamanjaro
Impact drivers are a new class of tool that showed up a few years ago and has been steadily gaining in popularity. Anyone who’s ever used one swears by it, but folks who haven’t don’t really understand them. On the face of it they’re just a drill that doesn’t have a chuck, and can only drive fasteners. However, all though they can only do one thing, they do that one thing very well. Today we are reviewing the light yet powerful Bosch PS40-2A Impactor 12V Li-Ion driver. It features 800 in-lbs of torque and a no load speed of 1,800 RPM. Not the most impressive specs, but it weighs just 2.2 lbs. It has a street price of about $120. Hit the jump to read the full review.
Background:
First a bit of background on impact drivers. While these tools may look like a cordless drill or screwdriver they are quite different. They are also significantly different than a car mechanic’s impact wrench. An impact driver starts out normally spinning like a regular drill. However, when the torque require to turn the fastener reaches a certain amount, it starts impacting. Hammers inside the driver hit the shaft very quickly (in this case at 3,000 beats per minute) putting out a tremendous amount of torque. This produces a large amount of torque, without wrenching the driver out of your hand. That is the same process as an impact wrench. What’s different about an impact driver though is that the driver also hammers axially as well. This pushes the bit into the fastener head at the same time as its twisting it, preventing the bit from camming out and the fastener head from stripping. Impact drivers can thus drive very long screws with little chance of stripping the head.
What you get:
In addition to the driver itself, you get a nifty soft-shell carrying bag, a short manual, two batteries, a charger, a Phillips bit, and a straight bit. The carrying case is well made of ballistic nylon, and has a place for a few bits, and the spare batteries.
The batteries are Bosch’s model BAT411. These little guys are 1.3 Ah, 10.8V batteries that Bosch (and most other manufactures) like to call 12V Max. The charger is Bosch’s BC430 30 minute model, and you’ll be hard pressed to wear out the battery faster than that. Therefore you should never have to worry about having a dead battery, unless you forget to leave one on the charger.
Design:
The driver itself appears to be very well designed, with one glaring omission which I’ll get to in a bit.
The battery easily snaps into place, and the barrel of the tool features a rubber bumper on each side to give it a bit of protection as well as keep it from rattling around in a metal toolbox. The bits are easily inserted or removed by pulling on the collet while simultaneously pulling on the bit. The bit is surrounded by three white LEDs which put off plenty of light. However the lights only come on when the trigger is squeezed. An override switch would be a welcome addition. The tool also features a rubberized grip to prevent slippage. The designer however spent to much time in an ideal environment, where all the fasteners were only one type, as there is no spot on the tool to hold a spare bit. A little clip on the back to hold a straight or square bit, while the Phillips is in use would be a huge help.
Use:
The driver fits extremely well in hands either large or small. Its quite light, but what heft it does have is very well balanced making it easy to use for long periods of time. Due to the impact nature of the tool, only a little force is required to keep the bit from camming out. The Impactor can drive a 4″ long Phillips screw into pressure treated wood. It is however still a lightweight tool, and while it can do that without issue, it does go pretty slowly. If you have more than a few to drive, you should really be looking at the 18V drivers. 
Where this little guy really shines is driving screws in awkward situations. Need to screw a 2×4 into the ceiling, in the dark? Its a piece of cake with the Impactor, it doesn’t weigh much so its easy to hold, and it only requires a bare minimum of upward force to keep from stripping the screw. Trying to do this with a regular drill would be an exercise in tiring frustration. As an added bonus, if you have large hands like myself, you can reach the bit with one finger and use it to hold a screw in place, while still being able to squeeze the trigger.
I’ve been using this tool for a few weeks now, and have used it for everything from driving long screws through hardwood, to little 3″ screws for hanging curtains. It’s a fantastic tool, and I rarely use my cordless drill to drive screws any more. The only other drawback I’ve seen is that as the battery wears down, in starts impacting sooner and sooner, but its not always obvious if that’s due to a low battery or a difficult screw. A simple battery level indicator would eliminate this issue.
Highs:
Can drive virtually any fastener regardless of size (albiet slowly), without camming out.
Incredibly lightweight.
Small size lets it get into places full size drills can’t.
Lows:
No spare bit holder.
No battery indicator.
Verdict:
A great tool that everyone should own.
Overall Rating: 9.5/10 
Gallery:
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