Whether it’s new construction or maintenance, many jobs require drilling holes in concrete. Selecting the right tool for the job is critical, but making the right choice can be complicated. Types of tools, bit holding systems and drill bit types, as well as nature of the job that needs to be done and availability of electric power – these are some of the variables that need to be taken into consideration.
Rotary hammer: A tool that does rotary drilling using rotation and a hammering action that breaks up the concrete as the bit rotates. Rotary hammers are designed for day-in/day-out use.
Demolition hammer: Heavy-duty tool designed to chip or break up concrete.
Combination hammer: A dual-mode hammer designed to either drill or break up concrete.
Before selecting a hammer for rotary drilling, determine the diameter of the holes you need to drill. The diameter of the holes will dictate the type of hammer and the bit holding system you select. Every tool has its own optimal drilling range. By identifying rotary drilling tools with optimal ranges correlating with the dimensions of the holes required, you can decide which size tool is required.
By selecting the optimum hammer designed to drill the holes required, more efficient performance is guaranteed. Though operating the hammer rotary drilling within these ranges offers best results, each hammer also includes the flexibility to drill larger holes as well. The bit-holding system consists of the tool’s internal components that hold the bit in place and transfer energy from the electric motor and gearing mechanism to the bit. Most hammers for rotary drilling tasks utilize one of three systems: SDS-plus®, SDS-max® or spline. Spline is a popular bit holding system that has been used for many years, but is gradually being replaced by the superior SDS-max® system. Like doctors have specialties, each bit-holding system operates most efficiently and accurately within a defined range. For each system those ranges are:
SDS-plus: 3/16" – 3/4"
SDS-max: 1/2" – 1-3/4"
Spline: 3/8" – 1-3/8"
Though intermittent rotary drilling at capacity is possible, it’s always better to opt for the next larger hammer if any drilling series requires larger holes. Like any other tool or machinery, constantly pushing a hammer to its extremes will eventually lead to failure. Investing in the next larger hammer up front will pay off in the long run.
By selecting the hammer designed to drill the holes that are needed, users can guarantee faster and more efficient performance. One critical point to keep in mind when using a hammer for rotary drilling chores is to let the tool do the work; applying too much pressure on these tools can actually decrease performance.
In addition, each hammer incorporates the flexibility to rotary drilling of larger holes as well. Bosch SDS-plus hammers can handle carbide-tipped core bits from 2-1/2" up to 3-1/2", and SDS-max hammers can handle carbide-tipped core bits from three inches up to 6" and thru-hole bits up to 3-1/8". The exact size core and thru-hole bits are dependent on the hammer size.
Though occasional rotary drilling at full capacity is possible, you're always better off opting for the next larger hammer for continuous larger hole drilling. Like any other tool, constantly pushing a hammer to its extremes will eventually lead to failure. Investing in the next larger hammer upfront will pay off in the long run.
It’s also important to select a tool with the right functions. Bosch rotary hammers (SDS-plus) offer three modes of operation: hammer drilling, drilling only and chiseling only. Larger combination hammers typically offer two modes: hammer drilling and chiseling only.
When it comes to hammer carbide bits for rotary drilling, it’s best to think of hammers as a system. With all the improvements in power tools over the past few years, the carbide bits have been rapidly improving as well. From two-head cutters to four-head cutters (full head carbide) to bits that specialize in rebar to “stop bits” that control depth to avoid post tension cables, bits have been redesigned to be more durable for increased cutting speed and to keep pace with the increased impact energy of the hammers. Without these improvements, all that pulverized dust generated by rotary drilling would remain in the hole causing heat buildup on the bit tips and eventual bit failure.
In considering different brands of hammers for rotary drilling, take into consideration the overall durability and features of each tool line. Bosch makes some of the toughest tools on the market for rotary drilling, with internal gearing and motors designed to take the abuse of high temperatures and extreme applications. Bosch offers a full line of SDS-plus rotary, SDS-max and spline rotary/combination hammers. And as the world’s number one hammer manufacturer, Bosch has built a reputation for offering tools designed to perform and last. By understanding all of the different hammer options available, users can see why choosing the right rotary or combination hammer can make a big impact on the bottom line.
