Hand grips with lots of rubber surfaces, such as on the Bosch, really help when the tool becomes covered with masonry dust.
Credit: Photo: dotfordot.com
I performed speed and duration tests using a new 5/8-inch bit in each tool and performed the tests in the same section of a concrete foundation wall. The concrete was more than 40 years old, well cured, and very hard, and it contained 3/4-inch aggregate but no rebar.
Drilling Speed. The times for each tool are based on drilling 10 holes 4 inches deep in rapid succession with the trigger held down the entire time and averaging the overall time.
This included the time it took to move the bit between holes, which I estimate to be less than a second. I retested the fastest and slowest performers to see if their times were unduly influenced by more or less contact with pieces of aggregate, but I found the results to be on par with the first trials.
The fastest hands-down was the Bosch at 12.8 seconds. This speed is undeniably related to the fact that it also was the loudest and vibrated the most, but when I wanted to get the job done in a hurry, I would reach for the Bosch.
The Hilti TE 7-AC took 18.3 seconds, the Milwaukee 18.8 seconds, the 36-volt DeWalt 22.8 seconds, the 18-volt DeWalt 24.5 seconds, the Panasonic 26.7 seconds, and the Hilti TE 6-A LI 26.9 seconds. The Metabo took 48 seconds, and the Makita only made it to eight-and-one-half holes at 36 seconds each.
Holes Per Charge. For the battery duration test, I simply drilled holes 4 inches deep on a full charge until the battery ran out; again, I tested the highest and lowest performers twice.
The accordion-style dust cup on the Panasonic EY6813NQKW snaps onto the front of the tool for basic dust containment.
Credit: Photo: dotfordot.com
The winner here was the Hilti TE 7-AC with 29.5 holes–a respectable amount of work out of a cordless tool. The Hilti TE 6-A LI completed 23 holes, Milwaukee 22.5, Bosch 19.5, Panasonic 14.5, Metabo 14, 36-volt DeWalt 13.5, 18-volt DeWalt 12.5, and Makita gave up at eight-and-one-half holes.
My choice for overall winner is the Hilti TE 7-AC. It had the best balance of ergonomic qualities and high performance. I really liked its comfortable grips and controls and moderate vibration and noise output, but what put it over the top for me was the combination of the second-fastest hole-drilling time and the best drilling duration.
In a close second is the Bosch 11536VSR, which blasted through concrete with the greatest speed and decent comfort. The noise level and vibration are both high, but that's a price I'm willing to pay to get the job done quickly. The Milwaukee 0756-22 rounds out my top three. It's in the same league as the first two; it's about as fast as the Hilti and outlasts the Bosch.
Next in line is the DeWalt DC233 KL with decent performance and an even better spring-loaded body that significantly reduces vibration and aids the operator in judging how much pressure to use while drilling or chipping. Note that the top four all have the added benefit of a chipping mode.
The Hilti TE 6-A LI is next with average speed and the ability to outlast the remaining tools, followed by the Panasonic EY6813NQKW with mid-line speed and duration results along with its unique speed control.
The DeWalt DC212 KA is compact and well balanced, and has the same body suspension that the larger model has. The Metabo BHA18 had good, low vibration and noise rankings, but it was lacking in performance. The Makita BHR240 couldn't complete my hole test while all the others could, but it did have a comfortable feel and even a chipping mode.
–Rick Arnold owns R. Arnold and Sons Construction in North Kingstown, R.I., and frequently writes for trade magazines and speaks on construction topics across the U.S.
Thanks to Miyanaga America Corp. for supplying the bits for our test. 630-778-3496 www.miyanagaamerica.com