Rotary hammers are the next step above the common hammer drill, and unless you regularly work with concrete or masonry, you may not be familiar with their ins and outs. If you have a job that requires drilling holes in concrete, especially larger ones, then the rotary hammer is an indispensable tool.
Rotary hammers are used for drilling as well as hammering holes into concrete and masonry. They typically have multiple functions, including a hammer-only mode, a drill-only mode, and a hammer-drill mode.
Unlike hammer drills, rotary hammers are built for heavy-duty all-day use like you’d find on a job site. Most hammer drills also feature an SDS chuck – which makes them more suited to hammering than a standard drill chuck.
Let’s take a closer look at what a rotary hammer is used for and when to reach for one over a standard hammer drill.
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How does a Rotary Drill Work?
A rotary drill creates a powerful back-and-forth pounding action that generates enough force to blast through concrete and masonry much faster than a hammer drill. It’s able to generate this force using an internal piston and crankshaft to create air pressure and drive the drill bit back and forth.
This piston-driven hammering mechanism creates significantly more force than the disc-driven one found in hammer drills. It also means you’ll be able to run a hammer drill for hours on end without wearing out the mechanism or the motor.
As mentioned previously, rotary drills typically have multiple drill modes – so you can choose between a straightforward drill mode, a hammer drill mode, and a hammer-only mode. The hammer plus drill mode is probably the one you’ll use most when using a rotary hammer, as it enables you to create nice clean holes in concrete without breaking it all up into pieces.
Contrast that with a demolition hammer, which is used strictly to break up concrete and masonry and doesn’t have the ability to bore precise holes.
When do you need a Rotary Drill?
So, when would you actually need to use a rotary drill?
And when can you get away with using a hammer drill or even a standard drill/driver?
There isn’t an exact rule of thumb of when you need a rotary hammer over a hammer drill, but if you’re going to be drilling holes over 3/8-inch wide, then a rotary hammer makes sense. If you need to break up concrete or masonry, demolish tile, or do any job that requires all-day operation, then reach for a rotary hammer over a hammer drill.
Additionally, if the job requires you to break up large sections of concrete, or get down to the rebar, then you probably want to step up to a demolition hammer. These tools are better suited to heavy demolition work than rotary hammers, which can handle some of this work but aren’t the ideal tool for the job.
Also, keep in mind that rotary hammers aren’t exactly cheap tools. A quality SDS-plus model will run you about $300 to $500, so if you only need the tool for a specific job it probably makes more sense to rent it by the day than purchase it outright.
SDS Chuck
An important distinction to understand when it comes to rotary hammers is their SDS chuck. SDS stands for slotted drive system or slotted drive shaft and essentially uses bits with large grooves in them for superior grip between the chuck and the bit.
SDS chucks and bits come in a variety of sizes, so you’ll want to make sure you’re using the right-sized bit for your drill’s chuck.
When it comes to rotary hammers, most units will either be an SDS Plus or an SDS Max. These sizes refer to the size of the bit’s shank – 10mm for SDS Plus and 18mm for SDS Max. The increased size of the SDS Max means they have a higher capacity for heavy-duty work and will chip and drill through concrete and masonry with greater force.
As you might expect, SDS Max rotary drills are the more expensive of the two and tend to be the choice of pros who need to get serious work done. SDS Plus rotary drills can be a good option if you only need to use the tool occasionally, and you’ll save a good deal of money by going with the smaller-sized unit.
There are also SDS chuck adaptors available, which will enable you to use an SDS Plus bit in an SDS Max rotary hammer. This means you’ll still be able to can use smaller bits in your rotary hammer if you wish.
Drill Bits and Attachments
When most people think of rotary hammers, they probably think of drilling in concrete and not much else, but the reality is these tools are pretty versatile and can be used for a variety of jobs. Depending on what drill bit or attachment you have installed, you can do everything from breaking up hard soil to tile removal and even scaling metal to remove rust.
Some of the popular bits are as follows:
- Clay spade bit: A large shovel-headed bit designed for digging trenches and breaking up clay.
- Tile chisel bit: Wide flat-headed bit designed for removing tiles from floors and walls.
- Cold chisel: Chisel-tip bit designed for light chipping and chiseling of masonry and concrete.
- Bull-point chisel: Pointy-ended chisel designed for boring holes in concrete.
- U-shaped chisel: U-shaped tip designed for creating channels in masonry.
- Rebar bit: Carbide bit designed for cutting into and through concrete rebar.
There is a huge amount of variability when it comes to drill bits and attachments. If you’re shelling out the money for a premium rotary hammer, then it also makes sense to invest in quality bits.
Specialty bits you may be interested in are dust extraction bits, which actually have a small hole hollowed into the bit to extract dust as you use the bit. This is great for job sites where you need to keep dust to a minimum and prevent excess concrete dust.
Rotary Hammer Costs
When it comes to purchasing a rotary hammer, there is a good deal to consider. First off, you’ll want to consider your price range and what you need the tool for.
If you’re looking for a tool that can punch large diameter (1”+) holes in concrete all day long, then you’ll want to go with an SDS Max rotary hammer. Alternatively, if you plan to use the tool occasionally, and for less intensive work, then an SDS Plus rotary hammer will work fine.
When it comes to costs you can expect a decent SDS Plus unit to run you between $200 and $300, and a bit more for battery-powered units.
A decent SDS Max unit will cost a good deal more, ranging between $350 and $1000+ for top-of-the-line units. Keep in mind that a high-end unit can be rented for just $50 – $60 per day, so it often makes sense to simply rent one for the job rather than buying it outright.
