THE ROTARY HAMMER DRILL What does it do, and why should I pick it over a hammer drill?

in News

Unless you’re an old hand in the DIY game, chances are you’re confused by the myriad of power drill choices out there. It doesn’t help that the same tool often goes by various names. Our focus today is two specialist drill choices – the rotary hammer drill vs the hammer drill.

Sounds the same, doesn’t it? To some extent they are, in that both these drills perform a hammer-like function whilst drilling, making them suitable for hard-surface drilling. But that’s where the similarity ends because the science behind the hammering function is different, and that’s what makes these two drills very different indeed. Think of the hammer drill (aka impact drill or percussion drill) as Little Junior, and the rotary hammer drill (aka rotary hammer or electro-pneumatic drill) as Big Daddy. Let’s dive into the basics.

PISTON POWER

If one word sums up the difference between the rotary hammer drill and hammer drill, it’s power – specifically piston power. Unlike the hammer drill, which relies on small metal anvils behind the chuck to deliver concussive blows to the drill bit, the rotary hammer drill has an internal piston driven by a crankshaft.

The back and forth action of the piston in a sealed chamber creates a pocket of intensely pressurized air that drives a bolt ahead of it. It’s this bolt that slams into the drill bit at extraordinary speed and force, allowing it to move through the hardest of concrete like a hot knife through butter.

Bosch Rotary Hammer Drill 600W (GBH 2000)
R 1,895.00   R 2,650.00

 

MORE FORCE = LESS EFFORT

Normal hammer drills have a much smaller impact movement than rotary hammer drills, so it’s necessary to exert pressure on the drill, especially when drilling hard surfaces. That’s not the case with a rotary hammer drill – just point it and guide it, the rotary hammer drill does the rest. In fact, the more pressure a user applies to the rotary hammer drill, the less effective it becomes because the bit needs free movement to drive the forward impact force into the concrete whilst rotating at the same time. So little effort is required that you could probably use it one-handed, but of course we wouldn’t recommend that!

Rotary hammers don’t take normal smooth drill bits, but SDS Plus bits which contain grooves in the side at the shank end. These grooves allow the bit to slide in the chuck, increasing the strength and percussion rate of the bit into the wall even more.  The SDS bits slip securely into a special SDS chuck that, unlike a hammer drill, does not require tightening with an external chuck key.

 

Ryobi Rotary Hammer Drill 900W (ED-938)
R 1,285.00   R 2,250.00

 

A POWERFUL MULTI-APPLICATION TOOL

Rotary hammer drills don’t just drill holes into the toughest of tough substances. Various attachments turn it into an extremely effective chisel for lifting tiles, scaling metal, breaking concrete and even digging into hard soil.

Metabo Rotary Hammer Drill 800W (KHE 2644)
R 2,495.00   R 2,950.00

 

SO WHAT'S THE VERDICT?

Rotary hammer drills are the automatic choice for pros who know they need to do a loft of heavy-duty drilling. But it’s also a great choice for the DIY enthusiast. If you’re thinking hammer drill vs rotary hammer drill for your concrete, masonry and brickwork drilling, we think it’s worth it to spend a bit more and get Big Daddy. A decent brand will give you a lifetime of service. The rotary hammer drill in my tool kit has been there for 20 years, and it’s still going strong.