The drilling or screw driving capacity of the various types of cordless drill is largely determined by the voltage and battery capacity (Ah). Broadly speaking the higher the voltage, the bigger the hole it will drill or screw, and a higher battery capacity will usually give a longer run time for any given job.
As with most power tools the more you invest the more you will get. Particularly for tradesmen, spending a little bit more can often make a significant difference to the performance and flexibility of the tool and dramatically improve the return on investment over the working life of the drill.
For any job, your requirements will affect the drill that should be selected. To assist you in choosing the right tool for the job in hand, below we evaluate drill drivers, combi drills and SDS Rotary Hammers, outlining their functions.
Drill Driver
Cordless drill drivers typically have two primary functions. In the first instance they are used for drilling holes in wood, plastic and metal, while the variable clutch function makes it suitable for driving screws accurately into various materials. Given the nature of the work, drill drivers of around 14.0v with a minimum of 2.0Ah batteries will generally be suitable for most tradesmen.
Combi Drill
Combi drills offer the same drilling and screw driving features as drill drivers, described above, with the additional feature of a hammer action to allow the drilling of masonry, brick and concrete. Typically an 18.0v tool with 2.6Ah batteries is adequate for most trade applications but tools with higher voltages and higher capacity batteries are available for situations where the workload is geared towards drilling larger holes in masonry.
SDS Rotary Hammer
SDS plus rotary hammers are available from various manufacturers from 14.4v up to 36v. These tools are designed primarily for the repetitive drilling of holes in concrete and masonry. Through the use of a small piston a much higher impact blow is delivered to the drill bit which is securely held by an SDS plus chuck rather than a three jaw chuck. This means that larger diameter holes can be drilled much faster than in masonry etc., than they would be by a combi drill.
The same rule of thumb applies where the higher voltage tools will drill larger holes faster improving the return on in investment which is all important to the hard working tradesman.