Amazingly compact, frighteningly powerful.
When you need to sink hundreds of screws in short order or assemble a lot of nuts and bolts an impact driver is the tool to use. Its impacting action generates far less torque reaction than a drill/driver, making it easier to control, and because of the combined rotational and impact force, less likely to strip screw or bolt heads.
There are dozens of different models of impact drivers available from the various power tool manufacturers. Most cordless versions are available in either a 12V or 18V (20V MAX) format, and all come with a 1/4″ hex shank. Weight, size, speed, impacts per minute and torque – the key features you want to consider when you buy an impact driver – vary considerably.
While the new DEWALT DCF850 is up against some tough competitors, I think it sets the new standard for compactness and power when it comes to 18V (20V MAX) impact drivers.
Model: DCF850B Bare Tool; DCF850P1 Kit
Price: $199.00 Bare Tool; $349.00 Kit
Warranty: 3 Years (tool and battery)
Made in: Mexico (tool); Malaysia (battery)
Source: Find a Retailer
Battery platform: 20V
Speed: 0-1000/2800/3250 RPM
Impacts per minute: 3,800
Torque: 1,825 in-lbs
Drive: 1/4″ quick release hex shank
Weight: 2.1 lbs (bare tool); 3.7 lbs (5.0Ah battery installed)
Includes (DCF850P1): Tool, 5Ah battery, charger, belt hook, contractor bag
With a head length of just under 4″ the DCF850 is the most compact impact driver on the market, which gives it a real advantage when working in confined spaces where you might otherwise need to resort to a right angle drill. It’s light weight (3.7 pounds with a 5.0Ah battery installed) means you can use it throughout the work day without putting undue strain on your wrist and arm.
Three intense LED head lights arranged around the chuck help make working in places with less than ideal lighting a lot easier.
Like most cordless power tools today, the DCF850 features a brushless motor, which delivers a longer battery runtime for increased productivity. A brushless motor also extends tool life because there is no brush or commutator erosion, and it delivers increased torque per watt of power input for greater motor efficiency and performance.
And the DCF850 really delivers on speed and power. You can choose from three speed modes with a top no-load speed of 3,280 RPM. With its 1,825 in-lbs of torque you can easily sink the longest framing screws and largest lag screws. I had no trouble sinking 3/8″ x 6″ lag screws and drilling holes with a 1/1-2″ spade bit and 4-3/4″ hole saw (the largest I have on hand). While it won’t replace an impact wrench the DCF850 can be used on a wide range of machine and lag bolts.
At the lowest speed setting (0-1,000 RPM) I found it just as easy to sink 1-1/2″ #8 screws with precision. This is due to DEWALT’s “Precision Drive Mode”. At the lowest speed setting the DCF850 operates like a screwdriver pausing for a second before impacting, driving small screws in flush with the work surface.
If you already use the DEWALT platform and have a charger and batteries, then opt for the bare tool. Otherwise you can purchase it in a kit that gives you the tool, charger, 5.0Ah battery and a belt hook, along with a canvas carry bag.
When it comes to installing electrical or plumbing conduit, steel or wood framing, decking, stair stringers, cabinetry and the like, the DEWALT DCF850 is one heck of a tool to beat.
Carl Duguay - [email protected]
Carl is a Victoria-based furniture maker and the web editor at Canadian Woodworking & Home Improvement.