Concrete drilling is a labour intensive task that can be quite dangerous if not carried out correctly. This guide will help you to understand the most important concrete drilling basics.
What Is Concrete Drilling?
Concrete is a tough material that is much harder to drill into than other, softer building materials such as wood and plasterboard. A standard steel bit will simply not be able to cut into concrete properly and cleanly, so most concrete drills use either a carbide bit or a diamond tipped bit.
Concrete Drilling Equipment
When you are drilling into concrete you have the option of using either an impact drill or a non-impact drill. There are two kinds of impact drills: they are the hammer drills and the rotary hammers.
With a conventional hammer drill, the bit is pushed into the concrete as it drills. Hammer drills are quite small and use a ramped ratchet system which applies a high speed vibration or rattling action to the 3 jaw chuck, speeding up the drilling process. Usually, hammer drills are used with percussion carbide bits. Do not try to use conventional carbide bits with a hammer drill because they are not strong enough to hold up under repeated impact conditions.
Rotary hammers are similar to hammer drills; however,they are much more efficient. Instead of using a ramped ratchet system, they have a piston/crankshaft assembly which will beat on the end of the drill bit. The bit itself can slide freely within the tool holder, and hammers back and forth as it turns. Again, you should use a carbide tipped bit with this kind of drill. You can drill holes that are up two four inches in diameter using a rotary hammer, while standard hammer drills are capable of drilling holes only half an inch in diameter.
Non-impact drill bits can be used to drill holes that are 10 inches or more in diameter. They do not apply an impact to the surface that is being drilled, so the drill bits must be a lot stronger. Usually, diamond core drills are used for non-impact drilling. You need a large rig to drill without impact, and there is usually a lot of set-up work required, in addition, the drilling time takes a lot longer.
In some non-impact drilling setups, a vacuum pump is employed to suck the drill down to the floor. This can only be used if the surface is smooth and free of cracks. Otherwise you will need an alternative setup.
Drilling with diamonds is a complex process. The diamonds grind away at the concrete and the resulting friction creates a lot of heat. If you do not keep the drill bit cool then the matrix that the diamonds are embedded in will overheat and start to glaze over, making it useless for drilling.
Usually, the bit is kept cool by keeping a steady stream of water running over it at high pressure. This water will form a concrete slime as it mixes with the dust created by the drilling process, so you will also need a vacuum cleaner to remove the slime.
Diamond drill bits can drill holes that are up to ten inches in diameter, and drill for about 16 inches per pass. After that first pass you will need to pull out the core plug and, add an extension to the stump and the start drilling again. You can use this process to drill very deep holes, but this may be beyond a guide to concrete drilling basics.
The above are just a few of the most important concrete drilling basics. Before starting work be sure to read the instructions that come with the tools that you are using.
Take care to wear the right protective equipment, and look after your drilling equipment.
Remember that if you choose the wrong drill bits, or allow the drills to overheat you could end up causing serious damage to your equipment. Taking some extra time to source the right parts and getting your drilling right the first time will help you to avoid costly and inconvenient mistakes and ensure that the job goes as smoothly as possible.