First of all, if you're new to the world of impact drivers you have to get on board. It's just as simple as that! But seriously, if you're still driving screws/lag bolts/whatever with a drill or a ratchet, you're just working too hard. The torque is astounding, and this unit nearly matches the big beefy pneumatic impact drivers in a much nicer package. So when you see those giant lag screws you need to attach that deck ledger with you will not even sweat putting them in.
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br /I think the bigger advantage is that, unlike a drill, the impact action means that the torque is in bursts so it doesn't crank the drill around. With a drill you are usually doing just as much work as the drill (though with a bit of mechanical advantage). Even screwing in a bunch of smaller screws requires you to counteract the twisting force. Not so with an impact driver. You can virtually drive small and large screws alike with two fingers (the way you'd hold a wine glass).
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br /Now about this tool in particular... This tool is meant to drive screws more than large bolts. I have a beefy impact driver I use for most of those applications simply because the tip of this driver is for a "standard" hex shaft bit with a ball-detent. I'm sure the driver has the power to drive them if you have the right bit. I've been using it for over a year now (I got it at a trade show the week it was released but before it was in stock). The battery life is outstanding. They hold their charges well between uses, and have survived banging around the back of my van for a while now.
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br /The fit, finish, and features are all excellent. The light is nice and now some others have copied it (though I do like the compact Makita where the light automatically turns on and off with the trigger), and comes in handy working in dark cabinets and tricky spaces.
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br /The battery protection kind of made me pause the first time it happened, but it's a great feature and shows how Hitachi put in the extra thought in engineering for the new battery technology. Most competitors will let you run your batteries to the ground, which will quickly kill the life of your battery. The cost of the battery is a large part of the investment and I'm happy it doesn't let me cheat. Even if you know you should swap out the battery, how often would you stop immediately and get a new battery? You'd probably be like me and try to get that one last one. And just a couple more... Usually I don't like tools to think for me, but I'm OK, and actually thankful, with this feature. Now if only we could do something about those seatbelt warning bells...
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br /Anyway, the cost of this system is high, and I'm not sure if it's included in any of the packages, which is a shame because the two best pieces are the drill and the driver. My partner likes the compact Makita, but this thing will outwork it any (and every) day.

The first reviewer stated that he could not regulate the clutch on this driver and that the clicking was kind of loud - um, it's an impact driver - that's how they work, it's not a clutch that ratchets, that is the impact mechanism working - that's why there is twice the torque in an impact driver as in a standard driver-drill... This impact driver is stronger than almost all other brands, and actually is not as loud as most other brands.

This little machine is incredible. It is my most used power tool. I am a remodeler, I wasn't sure if I should believe the hype about impact drivers, but I gave it a try anyways. I have never looked back. As a professional this doesn't take the place of a Drill/Driver But for most applications it is faster and easier. (For a homeowner it would be a much nicer tool to have than a drill)
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br /Power. It has loads of power. The speed is very good, especially when it isn't impacting. It takes less effort to use than a drill because of the impacting you don't need to push as hard on it to grip the screw. It also does a nice job with a drill bit, or even a speed-bor.
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br /It does look like a toy, but it is one of the nicest tools I have
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What a powerhouse! This will drive a 5/16" lag screw into 1 1/4" decking with no torque on my wrist! Will save me much time and fatigue.

Bought this back in Feb '08 and have used it a number of times for smaller projects, though my big projects are ahead. Impressed so far and I give it 5 stars for build quality, value, performance, and general coolness (I like the look that some find toyish).
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br /One area that I'd like to see improved is the grip. (This is entirely personal, and not major enough to detract from the overall rating of the tool) I have smaller hands and find the lower portion (ring, pinky finger) of the grip to be slightly larger than I like. For reference, try out the Makita Impact Drivers (Makita BTD140 LXT 18 Volt Lithium-Ion Impact Driver Kit, Makita BTD142HW 18V Lithium-Ion Cordless Impact Driver). They have the most comfortable grips IMHO. But this does not detract from the Hitachi which has more torque, faster RPMs, etc. (Exception being Makita's new BDT141 which has 1330 lbs. torque)
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br /Battery life has been outstanding. I have not drained the first battery yet, seen absolutely no loss of torque/RPM as happens with standard batteries. My 18V Black Decker 18V drill cannot hold a candle to the WH18DL.
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br /Another buying point for me is the little white (red on some) switch on the handle that allows you to slow the RPMs. Handy when you don't want to drive too fast. Makita does not have this option, fwiw. In the fast mode you get from 0-2600 RPM and in slow you get from 0-2000 RPM - and it makes a big difference. The Makita models go fro 0-2300 RPMs only. So for me, the Hitachi allows for more nuanced work.
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br /Uses: I've used this for BOTH drilling and driving. Drilling is not its strong point but it works and works well. I've used a 1/2" spade bit to drill through 46 year old 2x6 rafters. Was like slicing through butter.
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br /But when I used a regular hex drill bit - 1/4", the ratcheting mechanism kicked in for a brief sec and things slowed down a smidge but still finished the job well. Awesome to have one tool to accomplish both tasks.
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br /Using high-speed mode was really impressive. Driving and unscrewing screws, lag bolts, etc., is super fast and easy. Unscrewing 3.5" wood screws was so fast I had to let the fasteners cool down before I handled them (in pressure treated lumber).
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br /Using the WH18DL to hang drywall is a breeze. I have a bigger drywall project coming up, but so far, most screws are set perfectly (using the slower mode). The ratcheting starts just as the screw sets so you can back down and get a perfect drywall set w/o a drywall bit. Your mileage may vary.
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br /Don't think this tool is *only* for driving screws, bolts, etc. You can use it as a drill within reason (another reason I chose over the Makitas is faster RPMs). Drilling is not its primary function, but it will work fine for lighter drilling (haven't tried it in masonry yet, but on the list).
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br /The integrated LED light/belt hook is a nice feature, and useful though I thought it wouldn't be. I think I'd prefer a slimmer metal belt hook, though. And I like Bosch's light integration around the "chuck" better. Jury is out as to whether the yellow LED is better than a white LED which other impact drivers have.
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br /If you have a honey-do list that is loaded with driving fasteners, then let your spouse know you have found a tool that will speed you through it like never before and leave you less fatigued to boot! :-)
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br /While I poured a lot of time into research, I did not spend a lot of time looking at DeWalt's offerings as they were beyond my price range. Though I did get my hands on them at the Home Depot. Decent, small like the Makita. Rigid's 18V ID was nice, but larger and heavier. If you want to see what the grip feels like on this WH18DL, you'll have to go to your local Lowe's and try out some of these green HXP Lithium Ion models (our Lowe's did not have this particular model but had the sister drill and others so I could get an idea of what to expect).
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br /I also looked at Bosch's 10.8V Litheon impact driver which is a great idea, but did not like the feel in my hand tho I loved the general size of it. The grip is thick all around, and its a nice unit otherwise. In terms of torque and RPM's, it is not in the same class as the Hitachi.
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br /So if you only use a drill (corded or cordless) to do your screw driving you don't know what you're missing. If you have ever torqued your wrist drilling a stubborn screw or lag bolt and ended up throwing back Advil caps as a result, this tool will be your saving grace. Torque is in abundance, but thanks to the ratcheting mechanism, it doesn't transfer to your wrist. So you can drive fasteners till the sun sets and be less fatigued when done.
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br /Overall: Highly recommended.
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br /-Value includes 5 year warranty compared to Makita's 3.
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br /-More torque, RPMs than equivalent Makita models in price range.
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br /-Good grip, a little "large" at the bottom of grip for those of us with smaller hands. Reason for the larger bottom is that it has a columnar battery post/insert as opposed to Makita's slide-in battery. Not sure which is a better technical design, but there you have it.
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br /-Use for driving fasteners AND light drilling
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br /Hope this review was helpful.

I've used my cordless impact every day at work for the past two months. It's lighter than my previous Hitatchi 14.4, and has way more power. The battery charges in around 45 min, might take longer now that the weather is getting warm. The only drawback I've found is when the battery dies... its dead, you can't squeeze one more screw out of it like you could with the old style batteries. It's like someone flipped a switch full power to no power when the battery dies. This could be problematic when working off a ladder or scaffolding, but with a 3.0Ah battery and a 45 min. charge time, just grab a fresh one before you head up. Highly recommended.

One of the best tools I have ever owned. By far the best drill ever made. The power is unreal, and it weighs nothing. I am a General Contractor and have been in the building industry for 23 years, I wish they made these Lithium Impact Drivers 23 years ago. It drives 3" screws into pressure treated wood like screwing a drywall screw into soft spruce. Incredible.

I purchased this about a month ago. After researching cordless impacts for quite a while I narrowed my search to three main ones. When it came down to the wire I wanted the most power, the best warranty, lithium ion and a quality product for the best price. The Hitachi is rated close in In./lbs. with the D.W. and the Bosch, it has a 5 yr. warranty and was well below the cost of the others and it came with 2 batteries and the charger. As a final determining factor of purchase was the overall weight as I am continually up and down ladders. The Hitachi is about a pound lighter than the Bosch which helped my decision.I have used the tool several times and am impressed with the power and weight of the tool. I would have given the tool 5 stars but the green and black design looks a little Fisher Price to me. I would recommend this tool to anyone as I am pleased with it.

As a dinosaur who's gone to great efforts to avoid buying cordless tools and/or anything made in China I finally succumbed after reading the latest Fine Homebuilding and Amazon customer reviews. I have a bunch of summer outdoor wood projects stacking up and decided to go cordless for the portability. I give the Hitachi 5 stars for fit and finish with solid construction and a rubberized outer cover to absorb shocks and bumps. The collet type chuck is easy to operate and the small size and light weight of this thing are truly amazing! The forward/reverse switch is a simple finger/thumb operation. While I haven't needed the light yet it can be aimed at the work so that could be handy when you're finishing up that last few pieces in the dark or under a cabinet. Stainless fasteners definitely need pre-drilling as three inchers will go right to the end before the head pops off! I switched to star drive coated steel and haven't had a problem since. As for the color scheme, I love it. You definitely won't get it confused with those "other" brands on the jobsite. And if it somehow disappeared I would definitely replace it with the same model!

This is just fantastic. Hitachi hit a homer with this impact driver. I've driven 4" screws into oak with this thing with no effort and was just amazed. I am slowly switching all my cordless drills over to hitachi, they make an excellent product- this driver is proof!

This is a great product from Hitatchi.
br /Pros: strong driver for long screws into wood, compact size and weight, long battery life, cool alien pattern on handle, good quality case, ease of use
br /Cons: there is no way to regulate the clutch on the driver function so it starts to ratchet when a certain amount of torque is detected, the rachet function is kinda loud when you are driving screws