The hammer drill for all your drilling needs
If you’re thinking of adding a hammer drill to your arsenal of masonry tools, you’ll be looking at two types: a hammer drill or a rotary hammer drill.
They sound the same, but while they can do some of the same jobs, there are some definite differences you should consider before putting one to work.
Hammer drills use a traditional three-jaw chuck and can drill into masonry, light concrete, stone and wood. In fact, anyone working around concrete, drilling holes to set framing, or mounting racking to the floor of a warehouse, will tell you a hammer drill is the tool for the job.
The bit rotates while delivering a series of blows to advance the bit through the material. The blows pulverize the material as the rotation moves the material out of the hole in the flutes of the drill.
“A hammer drill is ideal for the contractor seeking maximum versatility,” says Wayne Hart, communications manager, Makita. “Makita hammer drills can handle a range of drilling and driving tasks in wood and other materials, so it can be used in many different areas, such as HVAC, woodworking, plumbing, electrical and more.”
A hammer drill generates vibration via a cam action advancing and withdrawing the chuck. The bit advances slowly and the hammer blows are relatively light. Generally, the capacity of the hammer drill in concrete is limited to a hole diameter of ½ to ¾ inch.
Rotary hammer drills
Rotary hammer drills are solely for drilling into concrete, usually drilling holes for utilizing concrete anchor fastening solutions that can bare significant weight. They’re specifically designed to make sure they hit the bit as hard as possible, wasting no energy.
The more-powerful rotary hammer drill uses an electro-pneumatic hammer and the drill advances much faster, a technology similar to the one that powers a jackhammer.
Getting the work done
Although, traditionally, hammer drills were corded, recent advances in lithium battery capacity and the new brushless motor technology used in cordless tools, have made it possible for hammer drills and rotary hammer drills to go cordless.
“As the power tool industry evolves and expectations increase, users continue to demand drilling solutions that provide longer run-time than brushed motors can deliver,” says Cole Conrad, product manager for Milwaukee Tool. “The brushless motor in Milwaukee’s M18 Fuel ½-inch Hammer Drill, for example, works harder and lives longer, while reducing noise and cooling more rapidly to deliver years of maintenance-free performance.”
In addition to improving the life expectancies of cordless tools with brushless motors, manufacturers have increased battery power and run time, another change that benefits the hammer drill and rotary hammer drill user.
“The power and run time of Makita’s 18V LXT Brushless Hammer Driver-Drill (XPH07T) is setting new standards in efficiency and allowing contractors to unplug the cord for applications traditionally associated with corded drills,” says Makita’s Hart.
If you’ve been thinking about trying a hammer drill, save money and get a cordless model as part of a kit. Manufacturers are offering such good deals in combo kits that, depending on what you select, you might get the hammer drill almost free.
“In producing RIDGID’s Gen5X Hammer Drill we dissected every component to maximize performance while maintaining end-user value,” says Jason Swanson, VP of communications/PR, RIDGID. “The new Gen5X 5-piece combo kit with hammer drill, impact driver, circular saw, reciprocating saw and LED flashlight is an excellent value.”
Hammer drill features
If you’ll be using a rotary hammer drill regularly, you’ll want to consider the rotary hammer drill’s performance, of course, but for maximum ease of use check out the drill’s vibration reduction features. For example, Makita’s AVT (anti-vibration technology) consists of an internal counterbalance system that greatly reduces vibration by moving a counterweight in the opposite direction of the drive piston, reducing vibration dramatically.
“Makita’s new HR4013C Rotary Hammer Drill with enhanced AVT has the lowest vibration level in its class while delivering 20 percent more impact energy,” says Makita’s Hart. “In addition to the air-actuated counterbalance system, the entire housing is isolated from the motor and drilling mechanism, reducing vibration even more.”
Both hammer drills and rotary hammer drills provide operating modes. You can set either one to bit rotation only or you can use rotation and hammering together. And if it’s a hammer drill-driver, you can also select drive mode for driving screws.
Operating modes on rotary hammers are drill-only, drill and hammer, and a third option: hammering without rotation of the bit. In this mode, a chisel is locked in position to chip away at concrete or remove a tiled floor, for example.
The hammer drill’s trigger should have a variable-speed control so drill speed can be set to match the material. And be sure the trigger and reverse switch are easy to reach and easy to use, even when you’re wearing gloves.
Some hammer drills have a lock-on feature, which is convenient for continuous drilling over extended periods of time. However, before connecting the drill to a power supply source, always check to be sure it is not in lock-on position by depressing and releasing the trigger. Never use the lock-on feature in applications in which the drill may need to be stopped suddenly.
When repeated drilling to a specific depth is required, you’ll appreciate a drill with an adjustable stop to maintain the desired hole depth.
For added convenience, get a hammer drill with a chuck light. “RIDGID’s hammer drills,” says RIDGID’s Swanson, “feature a chuck light that shines directly out of the chuck onto the work, eliminating shadows around the bit.”
Another valuable feature on rotary hammer drills is a dust extraction accessory that is positioned against the drilled surface and works with a shop vac. Some have an on-board dust capture system, another useful feature.
Smaller and lighter tools will always be more comfortable to work with all day, while bigger and more powerful tools will be more efficient for heavy-duty larger dimensions drilling projects.
“Keep in mind that you can bring the biggest “baddest” hammer to the project,” says Mitch Burdick, concrete drilling product manager for Bosch Power Tools, “but just like your car, each hammer drill and rotary hammer drill has an optimal drilling range that makes it super-efficient and so the fastest and most comfortable to work with for an extended time.”
Drill bits and shanks
A hammer drill usually uses a smooth-shank masonry bit in a regular chuck. However, the greater force delivered by the rotary hammer drill and its hammering action would overcome a regular chuck. Instead, these more-powerful drills have special chucks designed to grip and lock the bit. As a bonus, these chucks are quick release for changing bits or chisels with ease.
The standard configurations for chucks are SDS+ and SDS-Max. On older rotary drills, you might also find a spline chuck. SDS+ chucks hold bits designed to drill holes from 5/32 to 1⅛ inch. SDS+ chucks will also hold carbide-tipped hole cutters up to 4-inches, and chipping and chiseling accessories.
The SDS-Max chuck is designed for heavier jobs using ½- to 2-inch carbide bits and hole cutters up to 6 inches. It can also hold demolition, chipping and chiseling attachments.
It’s possible to find both spline and SDS chucks, but on newer models you’ll probably be looking at an SDS chuck. If you already have spline shank bits and are in the market for a new rotary hammer drill, you can get an adapter that allows you to use splined bits in an SDS-Max chuck.
Tips for using a hammer drill
While operating techniques vary depending on the model, these instructions are a good guide.
- Drilling wood, composites and plastics – Select the drill operating mode and, using a high-speed steel bit, begin drilling at a very low speed to prevent the bit from slipping off the starting point. Increase the speed as the drill bit bites into the material. If you are drilling through holes, place a block of wood behind the material to prevent ragged or splintered edges on the back side.
- Drilling metal or steel – Use a light oil on the high-speed steel bit to keep it from overheating. The oil will prolong the life of the bit and increase the drilling action. Select the drill operating mode and begin drilling at a very low speed. Maintain a speed and pressure that allows cutting to continue without overheating the bit. Applying too much pressure will overheat the drill, wear the bearings, bend or burn out bits, and produce off-center or irregularly shaped holes.
To drill large holes in metal, start with a small bit, and then switch to a larger bit to finish. To drill copper, brass or aluminum, you’ll need to use a coolant.
- Drilling brick, tile, concrete, etc. – For maximum performance, use carbide-tipped masonry impact bits or hammer drill bits. Select the hammer-drill operating mode. In brick, begin by applying a light pressure at medium speed for best results. For concrete and other harder materials, you’ll then want to apply additional pressure as the job progresses.
To drill holes in tile, first practice on a scrap piece to determine the best speed and pressure for the specific tile. Begin drilling at a very low speed to prevent the bit from slipping off the starting point.
A smooth, even flow of dust will tell you you’re using the proper drilling rate. Don’t let the bit spin in the hole without cutting and don’t try to drill through steel reinforcing rods. Both actions will damage the carbide.
–By Steve Sturgess, stevesturgess.com