Buying guide for best rotary hammers
A good rotary hammer is a very versatile tool. With its combination of high torque and powerful impact, it can make substantial holes in a variety of materials. With the right bit, it will drill through concrete, brick, and stone a foot thick or more. Turn off the rotary action, insert a chisel bit, and you have a comparatively lightweight and compact demolition hammer.
There’s plenty of choice, from affordable models for those who only have occasional use to premium tools for the professional, but with a variety of sizes and specifications available, it’s not always obvious which is the best tool for the job you need to tackle. If you’ve only got a single task in mind, buying a budget rotary hammer can be cheaper than hiring one over the course of a couple of days. On the other hand, if you use one regularly, you’ll probably want a high-performance alternative.
We’ve undertaken an in-depth review of all the current models and made some recommendations. To explain the features in detail, we’ve put together the following comprehensive buying guide.
Key considerations
Corded vs. cordless
As with most power tools, you have a choice of corded or cordless.
Corded: These tools generally run anywhere from 8 amps to 14 amps, around twice that of a normal hammer drill (none exceed 15 amps, because that’s the maximum a standard outlet can supply). It’s pretty much a case of more amps equals more power.
Cordless: It’s not so straightforward with cordless models, which have two figures to think about: volts (V) and ampere hours (Ah). The tool itself is rated by volts, which equates to the maximum power available. The most powerful tools right now are 36 volts. Ampere hours relate to the battery and can be looked at like fuel. To fit a 20-volt tool, the battery must be 20 volts, but might be anywhere from 1.5 to 9 ampere hours. The bigger the number, the longer the battery will provide consistent power. We’d like to see at least 4 ampere hours on these tools because of their high demands. That has to be balanced against cost: those high ampere hour batteries are expensive.
Expert Tip
If you’re buying a cordless rotary hammer, a brushless motor makes much more efficient use of battery power than a brush motor, and it requires less maintenance.
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Features
Torque and impact rate
The two main factors to consider are torque, or twisting force, usually given in foot-pounds (ftᐧlb), and impact rate, usually given as blows per minute (BPM). You may also get a revolutions per minute (rpm) rating for the drill action, though these tend to be quite a lot lower than for an ordinary drill, and it’s not a feature that’s of major importance. With a rotary hammer, you’re looking for the power to drive the drill bit through tough material, not rapid rotational speed.
In general, bigger numbers are better. However, bigger numbers almost invariably mean a larger, heavier tool, and that can be tiring if you’re using one all day. It’s tempting to buy the most powerful machine you can afford, but it isn’t always the best choice.
Chuck size
Another good way to judge performance potential is to look at the size of the chuck. Most entry-level rotary hammers start at 1 inch. While pro tools can also be this size, they can be up to 2 inches on high-performance models.
Vibration
Along with weight, vibration also contributes to fatigue. When you’re handling a tool that is like a hammer striking an object thousands of times a minute, it can quickly numb your hands and arms. Good tools offer anti-vibration features: shock absorbers in the handles that do a good job of damping, and technology that balances the motor, thus reducing the effect at the source. Nevertheless, it’s recommended that you take frequent breaks.
Trigger
The trigger is usually variable speed, so you can adjust it to suit the circumstances on the fly. A lock-on button is useful so you don’t have to maintain finger pressure. Some rotary hammers offer a soft start, so you don’t get the full impact as soon as you squeeze the trigger.
Cord
Length: Good cord length is a bonus, so you don’t have to keep hunting around for an extension cord.
Extras
Reverse: A reverse gear can make it easier to release long bits from holes, but it’s not a common function.
Dust extraction: This is available on one or two tools, but it is usually an extra. It is certainly worth considering.
Responsive circuits: On some rotary hammers, responsive circuits can measure demand and increase power accordingly.
Sliding depth gauge: One might be provided with the tool.
Case: A case is always nice to keep things tidy and protected on the jobsite.
Warranty: Check the warranty, not just the length but also what’s actually covered.
Expert Tip
Check if any bits are included with your rotary hammer. At minimum, you’ll probably want a drill plus flat and pointed chisels. Some kits include them, but many do not.
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Rotary hammer accessories
Bit sets: XtremepowerUS Bit and Chisel Set
Even if the rotary hammer you buy does come with a couple of drills and chisels (and many don’t), you’ll soon find the range is too small for all the jobs you want to do. Fortunately, additional bits are not expensive, and this comprehensive 17-piece SDS Plus set is a good example of what’s available.
Dust collectors: Bosch HDC250 Dust Collection Attachment and DeWALT D25301D Dust Extractor Telescope
Dust from concrete and other materials can obscure your view and is dangerous to your health. Two different styles of device are available to combat the problem. The first is a low-cost unit that is placed on the surface being drilled. We’ve chosen Bosch, but many other brands are available. The second (we’re showing a DeWALT version) fixes to the rotary hammer itself and is perhaps more convenient, though it is the more expensive option. A hose is often provided, but you need a shop vac or similar to connect it to.
Rotary hammer prices
Inexpensive: The cheapest rotary hammers are in the $80 to $100 range and usually offer quite a comprehensive kit. The challenge is with reliability. If you get a good one, it’s perfectly adequate for occasional home use. Unfortunately, quality is often a bit hit or miss.
Mid-range: There are some decent rotary hammers at around the $110 to $150 mark, though you’re probably looking at $200 to $300 for a durable, heavy-duty tool.
Expensive: Fully featured, professional rotary hammers are likely to be in the area of $500, and high-end cordless models can exceed $750.
"The chuck on a rotary hammer grips differently than that on an ordinary hammer drill, so you can’t use your standard drill bits. However, adapters are available.
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Tips
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Wear safety gear. Rotary hammers create lots of dust and flying debris. Always wear safety glasses or a face shield. Some kind of respiratory protection is also advised.
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Wear work gloves and boots. You’ll get a better grip and protect your hands if you wear work gloves. If you’re doing demolition, protective footwear is also recommended.
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Use both handles. A rotary hammer can generate a lot of torque, which is why it has two handles. When drilling, use them both all the time. If a bit jams, the tool itself can twist violently — too fast for you to react. The result could be a severe wrist sprain and possibly even a break. Better models have a clutch or anti-kickback device that would normally prevent this, but you can’t be too careful.
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Turn off the tool. Never attempt to change between actions while the tool is running. It doesn’t work, and you’ll likely damage the transmission.
Other products we considered
Don’t see what you need in our matrix? We found a few more options for you. For the money, it’s tough to beat the 1.25-inch ENEACRO Rotary Hammer. It’s a powerful tool, and the kit includes three drill bits, two chisels, a chuck converter, and spare motor brushes.
It offers outstanding value for DIY use. The 20-volt Skil Cordless Rotary Hammer is a bit of an oddity. You wouldn’t want to use it much for demo work, but it’s definitely way more powerful than a standard hammer drill. It’s also very compact. If you’ve got a lot of heavy-duty drilling and driving to do, it’s a versatile alternative to an impact driver, and the bargain price includes a battery and charger.
Looking for a pro-grade cordless tool? The 36-volt Bosch Rotary Hammer is a tough, high-performance machine with all the features you expect from the brand, but the price is one for serious users only.
FAQ
Q. Does a rotary hammer need much maintenance?
A. No. These tools are often used in environments with lots of dust and grit, so wiping it down after use is always beneficial, especially around the chuck, to stop dirt from getting into the mechanism. The other regular task is lubrication, which is very important. A tub or tube of heavy-duty grease is often included with the tool.
Q. Are all rotary hammer bits interchangeable?
A. No. Some rotary hammers take spline bits, others use variations of a slotted drive system (SDS). Additionally, SDS comes in two sizes: basic and SDS Plus, which is 10 millimeter, and SDS Max, which is 18 millimeter. One does not normally fit the other, so it’s important to check when buying. Adapters are available, but they’re expensive. In most cases, they cost more than a good set of bits.
Q. What’s the difference between a rotary hammer and a demolition hammer?
A. Basically, the demolition hammer doesn’t have the rotary action. They are a type of jackhammer, so they can’t drill holes. As a dedicated tool, demo hammers are often more powerful than rotary models (though it’s not always the case), but the latter is obviously more versatile. Bits may be interchangeable, but you need to check the chuck type.
