How To Select The Best Hammer Drill

Rotary hammers vs impact drills

First of all, impact drills are not rotary/demolition hammers and should not be used for hard jobs like demolitions. Everyone knows the 10 minutes howling of a 500W impact drill whos owner (in vain) tries to drill a 1/4 inch hole for a book shelf.
The mechanical impact of a standard impact drill is strong enough to drill couple of holes in a brick wall but has - more or less - only a supporting function. Still, the main task of such drill is to drill holes to various materials... without an impact.

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What makes a rotary hammer... a rotary hammer?

The main difference between the rotary or demolition hammer and the impact drill is the impacting mechanism of the hammer which is pneumatic (or electro-pneumatic which is the same). The extreme impacting power of such mechanism makes even the drilling of thick holes into concrete an easy job.

How to drill with the pneumatic hammer

First off, don´t push the hammer drill too much. I am not joking. Pushing the hammer too much is the biggest mistake people usually do when drilling with demolition hammers.
The construction of the pneumatic impacting mechanism causes that the stronger you push the drill towards the wall the less power the impact mechanism can transfer to the drill bit. But back to the pneumatic hammer classification.

Pneumatic hammer classification

The manufacturers often recognize 2 main categories of pneumatic hammers:
1.) rotary hammers (do both drilling and hammering often called also combination drill hammers);
2.) demolition only hammers (no drilling, just the chisel);
You can guess that the majority of pneumatic hammers these days belongs to the COMBI category which means that such power hammer offers a fair comfort for its user no matter if he/she drills some holes in the walls or removes the old tiles in the bathroom.
Of course, for the real professionals who do these works daily, there are specialized tools available that do only demolition (but then they do it perfectly).

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How the power of the impact is measured

The power of the impact is often expressed in energy units, the Joules (J). The low-end products start at 1-2 Joules and the uber-professional demolition hammer´s impact energy can be as much as 60 Joules (something like a kicking horse packed in a 10 inch case, for experienced profis only (-:).

Features of a good pneumatic hammer

- various modes of operation - rotation only, rotary hammer, hammer only;
- variable-speed control - for accurate bit starting or finishing;
- reversing trigger - for removing fasteners or bound bits;
- SDS (bit system - for tool-free bit changing with automatic bit locking;
- D-handle design - for better control, ideal for overhead and downward drilling applications.

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