Bosch PS42 12v Brushless Impact Driver

Superb fit and finish, an insanely high torque level, dual speeds, and just over 2 pounds in weight makes this the 'uber driver'.

Bosch PS42 12v Brushless Impact Driver

Bosch PS42 12V Brushless Impact Driver

For drilling small holes and sinking small screws a compact drill/driver, like the Bosch PS22, is the tool to use. However, when you need to assemble a lot of nuts and bolts, or sink hundreds of screws in short order, particularly larger lag screws, an impact driver is generally a much better tool to use. The impacting action of an impact driver 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.

While 18V impact drivers are the best choice for carpenters and contractors, their smaller and lighter 12V siblings are an excellent option for renovators, service technicians, cabinet and flooring installers, deck builders, and avid DIYers. 

The new12-V Bosch PS42 has just about everything you'll want in a compact, light weight, high power impact driver. 

A compact tool in a compact case

The PS42 comes with two 12V batteries, charger, a belt clip, a Philips driver bit, and a fabric storage case. The BAT414 battery provides 2.0Ah of run time – about 50% more than their older 1.3Ah battery. Bosch also offers a 2.5Ah battery (BAT415) that you can use with the PS42 – it delivers 25% more run time than the BAT414. Recharge time with the BC330 charger is 1 hour. The charger has an LED that flashes while charging and goes solid when the job is done.

I prefer a hard shell case, but for something this small, fabric does the job quite nicely. It's just large enough to accommodate a small plastic container with a bit holder and a variety of driver bits and drill bits.

Bosch uses a 'Durashield' housing on all its power tools. It's a tough, flexible ABS nylon composite that does an excellent job of withstanding knocks, drops, and abrasion. While it won't likely withstand being tossed from the top of a 20-foot roof onto a concrete floor it will easily survive a benchtop drop onto a concrete shop floor (as I can attest). 

L to R: Bosch PS130; Bosch PS42

The PS42 is a very compact powerhouse, particularly in comparison to the PS130 hammer drill/driver that I've been using for the past four years. It has a head length of only 5-1/2" (7-5/16" for the PS130) and weighs only 2.1 pounds with battery installed (2.5 pounds for the PS130). You'll really appreciate that lighter weight when drilling or driving overhead, and the short head length when working in tight spaces or drilling and driving at awkward angles.

It features a brushless motor, which is becoming fairly standard on power tools now. A BL motor offers a lot of advantages over a conventional brushed motor – because it has fewer parts it's smaller and lighter; it generates less friction, heat and amp draw, which helps sustain battery run-time; it uses battery energy more efficiently, further improving battery run-time; and it's virtually maintenance-free. You can expect a BL tool to have a longer operational life than one with a brushed motor.

The BL motor coupled with the 2.0Ah battery deliver an impressive maximum impact rate of 3,100 blows per minute (BPM), a top torque level of 975 inch-pounds of torque, and a top speed of 2,600 RPM. Any way you cut the cake, these are very impressive figures for such a compact, light weight tool. 

The PS42, like all impact drivers, has a 1/4" quick-lock hex drive chuck – you install a bit simply by pushing it into the chuck and to remove the bit you pull on a spring loaded, ribbed, sleeve that surrounds the chuck. One advantage of this chuck is that it reduces the overall length of the driver head - so that the driver fits more easily into tighter spaces. A second advantage is that it makes bit changeover much quicker. The downside is that it doesn't accommodate standard drill bits and driver bits. To use these with the PS42 you could purchase a 1/4" hex quick connect – essentially a 3/8" keyless chuck that has a 1/4" hex shank you can insert into the hex drive chuck. However, be aware that the intense percussive force that an impact driver generates puts more stress on drill bits and drivers than does a conventional drill/driver, and it's not uncommon for standard bits to break or shatter in use. It's best to use impact ready bits and drivers with an impact driver.

Up top dust sealed controls

The LED light and speed and impact controls are quickly accessible on top of the tool. Unlike a lot of other power tools, the LED work light on the PS42 is user controlled. Push the bulb icon switch to turn the LED light on and off. The speed selector switch controls both speed and impact rate – one green LED light means you're using the lowest setting (0-1200 RPM and 0-2700 BPM). Press the control speed switch a second time and two green LED lights will illuminate, putting the driver in its high setting (0-2600 RPM and 0-3100 BPM).

Knowing which speed/impact rate to use comes with experience. I generally default to the lowest setting, and switch to the high setting only when using large diameter drill bits (1-1/4" and up) or sinking large and long lag screws (1/2" x 7" and over). 

On-board fuel indicator

The PS42 features the now standard battery fuel indicator (just above the trigger). When there is hardly any juice left in the battery a single LED light will begin to flash on and off, letting you know it's time to switch batteries. Otherwise you'll get sustained power until the battery goes dry.

Bright, focused LED work lights

I like the arrangement of 3 LED lights that surround the hex drive chuck as it provides better illumination and casts less shadows than a single light placed down on the bottom of the tool and angled upwards.


I've used the PS42 to sink upwards of 60 3/8" by 4-1/2" lag screws and still didn't tap out the battery. I've also been using it to set #8 2-1/2" pocket screws. I haven't take a formal count, but I estimate that I could sink well over a hundred of these screws on a single battery charge.

For me, the important features are the high level of fit and finish on this power tool, its outstanding compactness and light weight, and the superb combination of high torque, speed, and impact rate. The PS42 is surprisingly smooth in use, and I think you'll find it just as easy to control as a drill/driver. Yes, when the impacting action kicks in it generates a lot of noise. I registered it at X decibels, so you'll want to wear appropriate hearing protection. However, when drilling small diameter holes and sinking smaller screws its as quiet as a church mouse. 

So, if you'll be driving a lot of screws, particularly large or long lag screws, then you'll want to take a close look at the Bosch PS42. 

Key Features:

  • Motor: Brushless
  • Voltage: 12V
  • Chuck: 1/4" hex
  • Head Length: 5.5"
  • Width: 2.2"
  • Impact Rate: 0 - 3,100 BPM
  • Speed: 0 - 1,200 and 0 - 2,600 RPM
  • Torque: 975 in. lbs.
  • 3 LED lights
  • All metal gearbox
  • Battery gauge indicator
  • Weight: 2.1 lbs (battery installed)
  • Warranty: 1 Yr
  • Includes: Two 12V Max 2.0 Ah batteries, charger, belt clip, two screwdriver bits, carrying bag

MADE IN:1 year

Carl Duguay
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