As contractors in New York City, my crew spends most of its time pouring, cutting, drilling, and anchoring in concrete. For some framing and all mechanical and electrical work, we use rotary hammers on a daily basis to attach virtually anything to concrete, and the tool we reach for most is a 1-inch rotary hammer with three operating modes: rotary hammer, hammer only, and rotation only. The lightweight, compact size and ability to shift from hammerdrilling to chipping to simple drilling, and even driving, makes it the most versatile tool on our jobsites.
So we welcomed the opportunity to field-test this group of tools, five D-handle, in-line 1-inch corded rotary hammers, all of which feature three modes and accept SDS-Plus bits. The test comprised the Bosch 11255VSR Bulldog Xtreme, DeWalt D25203K, Hitachi DH24PF3, Makita HR2455X Pitbull, and Metabo KHE-D28. Given the fact that these are not the backbreaking big boys, we concentrated on drilling vertical and horizontal holes in concrete and stone within a 1/4- to 3/4-inch-diameter range (the 1-inch rating refers to the tool's practical maximum concrete hole-boring capacity). We also did plenty of light chipping and breaking and together used these tasks to evaluate the strength, ease of use, comfort, and helpful features of these tools.
When using these tools all day you find yourself constantly switching between rotary hammer mode for drilling and hammer mode for chipping and chiseling off high spots in concrete, so it's important to have controls that are easy to access. Throw on a pair of gloves and it becomes all the more crucial that the dials remain easy to operate and work with.
The Bosch, DeWalt, Makita, and Metabo tools all have well-designed and easy-to-grab side-mounted dials that turn easily to switch between modes, even with gloves on. We liked the Bosch and DeWalt dial markings, which feature clear symbols for the hammer-only mode bit-positioning setting, a nice feature to have when using larger chisels in small, awkward spaces because it allows you to position the chisel manually by twisting the bit. Makita's symbol was easy enough to decipher. The Metabo and Hitachi dials don't feature a symbol marking the chisel-positioning setting. We assumed they didn't have this feature until we looked closely at the manuals, which is not something you want your guys to have to do while on the clock.
We were not as impressed with the Hitachi's mode dial, which was located underneath the front housing of the tool. We found it hard to turn without gloves on and even more difficult with gloves on. Also, given its location, we found it prone to being whacked while drilling and chiseling in tight spaces, which seems like it could be a serious threat to its longevity.
D-Handles & Triggers
D-handle rotary hammers in this compact class are said to outsell pistol grip-configured tools in the U.S. market, and there are a few good reasons this might be so. The enclosed grip does offer your trigger hand some protection from nearby objects such as jagged rubble or protruding rebar when drilling and chiseling, especially when suddenly punching through hollow block or unexpectedly having your chisel skitter across a wall. But the main benefit is having the force applied by your trigger hand much more in line with the center of rotation and hammering. With the tool handle directly behind the bit, you can apply all the force you need while having your index and middle fingers comfortably wrapped around the trigger, not having to rely on only your lower fingers like when using an in-line grasp with a pistol-grip tool, giving you greater control.
All the tools in our test offer a large trigger in a D-handle that is easy to pull and hold while working, but the DeWalt and Metabo provide a little extra hand room around the trigger, which definitely comes in handy on cold winter days when thick gloves can make all the difference between misery and productivity.
Another trigger feature that can really help you during lengthy, repetitive drilling chores is the lock-on button. With the motor continuously running at full speed without a finger on the trigger, you are free to change positions and readjust your rear hand to change pressure on the tool and reduce stress on your hand and wrist. This feature is available on the Hitachi, Makita, and Metabo models.
Surprisingly, the largest variance in the group regarding triggers comes from their reverse features, even though reversing is usually only done when freeing a bound bit. (See "Reverse Logic," page 52).
Maybe I'm getting older and a little tired of working around hard concrete, but for me comfort and ease of use have become as important as any criteria in my tool selection, and they affect my perception of performance. Drilling and chipping concrete is a noisy, dirty business, and the better a tool combines power and comfort, the better it is for the user. So you just can't judge a tool like a rotary hammer without considering ergonomics, and it played a big part in our evaluations on the jobsite.
When we looked at ergonomics, we concentrated on grips, vibration, and noise. All these rotary hammers have rubber-cushioned rear grips, which we felt helped out with controlling vibration and minimizing hand fatigue. As far as handle comfort is concerned, the Metabo was our favorite, with an octagonal rubber grip on the side handle that definitely had the best feel. Bosch also has a rubber-paneled side-handle grip, though it was not quite as comfortable as the Metabo.
The other three models all have hard plastic side handles. Even though the DeWalt side handle is not padded, it is flared out on the bottom, which helps keep your hand on the grip. The Makita and Hitachi have adequate side handles. Makita's has a unique feature: teeth that mechanically lock the side handle in the desired position on the nose of the tool; it's a little more work to adjust, but once it's on, it won't rotate around the tool, even if the handle is a little loose.
As far as overall vibration and noise are concerned, Metabo vibrated the least and was the quietest, followed by DeWalt, Bosch, Makita, and then Hitachi.
All the tools in the test performed well and each held up to the rigors of pounding and drilling concrete on the job, so we performed a side-by-side test with all the tools using new, identical 1/2-inch SDS-Plus bits to determine any performance differences. Using our jobsite conditions, we drilled a series of vertical and horizontal holes in reinforced concrete and then moved on to fieldstone.
The Hitachi was tops in terms of raw speed, getting the job done quicker in terms of drilling and chipping, but its vibration and noise quickly became annoying, and we didn't like sacrificing comfort for the speed delivered. Bosch, DeWalt, Makita, and Metabo were virtually identical in terms of power and all had the ability to get the job done; however, the Metabo seemed to have the most consistent power over the range of material, most likely due to its unique electronic speed control feature that works to keep its rpm constant even under load.
We also liked the "health" control on the Metabo, which blinks a warning when the tool gets too hot or the brushes become worn. It's a nice feature I am sure will add life to the tool over the long haul.
All the tools tested except for the Metabo have a chuck with a slip collar that releases the bit when you slide it back. Loading the bit with this type of collar is easy. Simply push it in and rotate until it you feel it click in and engage. All four of these chucks look slightly different, but they operate the same way.
Metabo, on the other hand, uses a twist chuck. This requires the operator to twist the chuck to load and release the bit. It's not quite as easy as the slip-collar chuck, but it's not a deal breaker, either.
The dust seal at the end of the chucks is an important feature, sealing in the grease while sealing out abrasive masonry dust. Rubber dust seals that stop spinning when contacting a hard surface will end up lasting longer. The Bosch, DeWalt, and Makita seal ends stop spinning readily with a light touch; the Hitachi takes a lot more friction to stop. The Metabo doesn't free-spin, but the end is capped with smooth metal so it should hold up as long as the rest.
We liked that the chuck on the Metabo can be easily removed and replaced with an optional accessory drill chuck for more versatile drilling and driving applications. The bottom half twists and instantly releases the entire chuck from the tool's drive end.
Bosch and DeWalt have a clever depth-gauge design. On most rotary hammers, the depth gauge is set by tightening the side handle, which locks itself into place, as well. These two models have a depth gauge-locking configuration that is independent of the handle-cinching mechanism. A spring-loaded button clamps down on the depth gauge, engaging teeth that provide a slip-proof lock that is easy to adjust.
We also liked the cast-aluminum housing on the front of the Metabo. Since this is the business end, we like to see a heavy-duty material carrying the brunt of the punishment. New, durable plastics work well enough, but I prefer the toughness of metal. Bosch's housing has added durability with rubber patches on the plastic housing in known wear areas.
All five of these tools performed powerfully and well in our field-tests, doing just about everything we asked of them, so it was hard to pick a favorite from this group. But it was also hard to ignore how much the ergonomic features and performance meant to us as the test wore on. So we have picked two tools that stand out above the others in this class, one for overall performance and comfort, and the other for power and speed.
Our overall favorite is the Metabo. We liked its heavy-duty housing and thought it did the best job controlling vibration and noise while delivering steady performance. We also liked the removable chuck that could add greatly to the versatility of the tool.
For raw power and performance, we have to hand it to Hitachi. This model provided blazing-fast drilling and chiseling–so this is the tool for just getting the job done.
After these two we felt that the Bosch and DeWalt were about even, with the Makita close behind.
–Erik Elwell owns Thompson Construction, a high-end residential and light commercial remodeling firm in New York City.
–Thanks to DRILTEC for supplying the bits for this test.
Why do different rotary hammer manufacturers deal with the reverse motor function so differently on otherwise remarkably similar tools?
The main reason is that universal motors found in most portable power tools are built with a forward motor pitch or lead, which effectively gives the motor more power in its forward direction by altering the instant of commutation, or firing–similar to advancing the timing in a vehicle's engine. Technically, moving the brushes or stator relative to each other defines motor pitch, while changing the electrical timing of the armature bars defines bar lead. Advancing one of these three components gives the motor more torque because the driving electromagnetic attraction is timed to be applied at the optimal point to provide the highest force to spin the armature in forward mode. Consequently, in this biased configuration, the power in reverse is reduced and the brushes suffer very heavy sparking and diminished life–a situation called "poor commutation," which also causes high levels of radio frequency noise interference.
When tuned for forward performance, the stationary stator's magnetic field distortion caused by the rotating armature's magnetic field is dealt with more efficiently and radio interference transmission is minimized. Motors that only do work in forward, such as in miter saws, are often fully optimized for forward pitch or lead, but tools that are commonly used in reverse, such as drills, are configured in a more neutral position to allow for adequate power in both directions. Some rotary hammer manufacturers, realizing that nearly all the work this type of tool will ever do will be in the forward direction, take advantage of the benefits afforded by wiring a motor with a forward bias. As a result, the reverse power can be compromised. Here's how our tool manufacturers dealt with the variables and how it affects the reverse mode of their tools.
Bosch: Features a patented Rotating Brush Plate that provides equal power and speed in forward and reverse. This feature increases brush life by placing brushes in a position for clean commutation in both directions.
DeWalt: Has a forward-biased motor with reduced power in reverse but full speed at no-load. The reverse power is designed to be adequate to back out masonry anchor screws.
Hitachi: Has a forward-biased motor and a reversing switch that mechanically limits the trigger to half-capacity and disables the trigger lock-on operation. The reduced current flow to the motor in reverse is done to comply with some foreign markets' strict thresholds for radio frequency noise interference transmission.
Makita: Same as Hitachi. The company also notes that reverse limitation also prolongs brush life.
Metabo: Features rotating brushes that provide equal optimized power and speed in forward and reverse. The trigger lock-on can be used in reverse. Interestingly enough, some Metabo rotary hammers in the past actually featured a motor bias that resulted in the tool being 30 percent more powerful in reverse than in forward! It was explained that there was sufficient power in forward for the tasks it was expected to do and that the 130 percent reverse bias was for extra breakaway torque for removing fasteners. Apparently, this feature was originally designed for Europe where multi-use tools are more prevalent and the same tool was intended to be used for drilling, driving, and removing anchors.