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Its Hammer Time! ... Hammer Drills VS. Rotary Hammers

June 26, 2020

Its Hammer Time! ... Hammer Drills VS. Rotary Hammers


The summer is finally here and you’ve decided this year will be the year you’re going to construct that pergola you always wanted in your backyard. You know for a fact that you have to drill down into concrete, and you look in your toolbox and all you have is a hammer drill. You begin to wonder; do I need a rotary hammer for this project?


A hammer drill is a fantastic tool to have, great for fastening and drilling. Overall an extremely versatile power tool, but is it enough power to drill multiple holes into cement? Let us talk about the differences between a hammer drill and a rotary hammer and why is one better than the other in certain applications and a time saver.


Hammer Drills

Hammer drills are constructed very similar to traditional power drills/drill drivers but with ONE major addition…hammering action! Hammer drills produces a pounding force (thus the name “hammer”) right behind the bit, which makes it efficient at drilling into masonry material. Mechanically speaking, a hammer drill has two discs with matching grooves. As the hammer disc rises up against the chuck disc with friction, it falls with impact. Creating the chuck to slam forward and backwards numerous times a second. This hammering action is measured in “BPMs” or beats/blows per minute.


Most hammer drills can be used as a regular drill by switching off the hammering action when brute force is not necessary. Like the DeWalt DCD996P2 20-Volt 1/2-Inch 3-Speed 5.0ah Lithium-Ion Hammer-Drill Kit. This 20V cordless kit includes one ½” hammer drill/driver, two 20V 5.0Ah batteries, charger, and hard case. When engaged in drill mode, you’re able to obtain 0-450, 0-1300, or 0-2000 RPMs. When switched over to hammer mode, you can unleased extra power from 0-500, 0-1500, or 0-2250 RPMs. With a BPM of 0-38,250 for fast drilling in masonry materials. Not bad at all for a power tool this size! This hammer drill comes equipped with a heavy-duty ratcheting nitro-carburized metal chuck with carbide inserts for superior bit gripping strength and a high efficiency brushless motor that delivers up to 57% more runtime over brushed. The DCD996 features a 3-mode LED providing light in dark or confined spaces and is 20X brighter than the previous model (DCD995). If you already have batteries and chargers laying around, don’t worry, you don't have to buy the kit. We also offer this as a bare tool under item number DCD996B.


Rotary Hammers

Rotary Hammers have the same idea as hammer drills and that idea is to drill through masonry material. However, rotary hammers take this to a whole new concrete drilling level. A rotary hammer creates its hammering action with a piston. When the power trigger is pulled, the piston moves forward with force inside the cylinder. This action simultaneously creates high air pressure within the cylinder walls and rushes the air pressure with strong velocity out to the hammer mechanism. This pounding power is measured in “pounds of impact energy”.


Not only does Milwaukee make great hammer drills but they also make great rotary hammers! Milwaukee is changing your perspective on corded versus cordless tools. For a long time, corded tools were always much more powerful than cordless…but not anymore. The Milwaukee 2715-22 M18 FUEL 18-Volt 1-1/8" SDS-Plus Rotary Hammer Kit is no exception to Milwaukee’s philosophy behind battery technology. This rotary hammer delivers faster than corded speed, corded durability, and all-day work on one charge. The brushless motor (POWERSTATE) provides 3.3 ft-lbs of impact energy, 0-1,350 RPM, and 0-5,000 BPM. This kit comes with 1-1/8” SDS-Plus rotary hammer, two 18V 5.0Ah batteries, multi-voltage charger (12V & 18V), and a hard case. This rotary hammer also features a total of three settings: rotation only, rotary hammer, and hammer only. What's great about hammer only is that you could use this (with the right bit) to break up small areas of concrete (like a mini jack hammer), chisel away tile, and/or remove mortar. If you are not interested in buying this as a kit, Milwaukee also sells this as a bare tool under item number 2715-20.


Chucks and Bits

Besides the power and the mechanical differences between hammer drills and rotary hammers. I would like to talk about one more aspect, and that’s the differences between the chucks and bits between these two machines. Almost all hammer drills feature a three-jaw chuck, just like any other power drill/drill driver. They are VERY common in today’s market and I’m more than positive your familiar with it. These chucks accommodate “straight shank” and “hex shank” bits.


Rotary hammers on the other hand operate with totally different chucks called SDS-Plus or SDS-Max. SDS bits (Slotted Drive System) have grooves on the shanks that lock securely into SDS-Plus/MAX chucks. They are designed to allow the bit to move forward and backwards independently of the chuck. Very easy to install and remove. They almost remind me of how impact drivers work.


SDS-Plus rotary hammers are by far the most common chuck type in this category and they only work with “SDS-Plus” bits. SDS-Max rotary hammers like the Makita XRH07PTUN 18-Volt LXT X2 Brushless SDS-Max Cordless Rotary Hammer Kit packs a bigger punch and only accepts “SDS-Max” bits. So, when you’re shopping for SDS bits, make sure you know what rotary hammer you have at home.


Do you need a rotary hammer!? You must ask yourself, how many concrete holes do you need to drill? How big in diameter are they? How deep do you need to drill them? And how quickly do you need to get them done? You can probably get by with just a hammer drill and a masonry bit, but I guarantee you it's going to test your patience. Even drilling a modest size hole into cement could take a few minutes. Any large diameter drilling will put A LOT of stress on a hammer drill. If you got to get a project done quick, easy and efficient, with little effort to no stress to your power tools, get a rotary hammer. It's all about having the right tool for the right job. I hope this helps!