Types of Tools and Bits
Concrete and masonry products are tough stuff compared to softer building materials so they require different technology when it becomes time to create a hole in them. Standard steel bits just won't hold up to masonry products so either carbide bits or diamond tipped bits are utilized. There is also two technologies available in drilling units, either impact or non-impact.

Hammer Drills
Impact drills are either known as hammer-drills or rotary hammers. They drill by applying impact to the drill bit as it rotates. Hammer-drills are smaller, more compact units that generally run up to a maximum of 1/2" diameter. They utilize a ramped ratchet system to apply a rattling action similar to a high speed vibration to a standard 3 jaw chuck as you push on the tools to help speed up the drilling process. Carbide bits are used in this setup and it is imperative that they be percussion carbide bits. Standard inexpensive carbide bits will not hold up under the impact of a hammer-drill.

Rotary Hammers
Rotary hammers are another type of impact drill. These are much more efficient than a lowly hammer-drill and consist of an actual piston/crankshaft assembly that actually beats on the end of the drill bit. These drill bits are allowed to slide within the tool holder so that they can hammer back and forth as the unit turns. These bits also are carbide tipped and are available in longer lengths that the hammer-drill bits. They can be used to drill holes up to 4" in diameter.

Drilling with a non-impact tool means there will be no hammering action present. A hammer-drill or rotary hammer actually works by driving the carbide tip into the concrete and then twisting off small chips. A non-impact drill only has rotation going for it so it requires friction to grind or cut through the material. Using carbide bits in a non-impact tool is going to add considerable time to your drilling project and is not recommended. Non-impact drilling does work well when using diamond tipped bits. Diamond bits do not hold up under impact situations but they do an excellent job of  grinding through concrete or masonry products.

Diamond Core Drills
Diamond core drills use not hammering action. One benefit of this is that no impact is applied to the surface being drilled. It does require a larger rig and setup time is longer but hole sizes up to 10" diameter are easily handled. When drilling with diamonds it is important to firmly mount the rig to the surface being drilled. Typically a vacuum pump is utilized to suck the drill to the floor. If the rig were to become loose it would damage the bit and you wouldn't have any way to apply forward force to the bit. A jack screw is found in the top of the column which can be used in combination with a 4x4 to prop the rig against an overhead ceiling. Also, mounting slots are included in the base of the rig to insert a temporary masonry anchor to clamp the rig down. These are alternative methods to mounting the rig when the vacuum setup doesn't work. If you are on a rough surface or there are cracks in the floor the vacuum won't seal up and one of these alternatives will then have to be employed.

When drilling with diamonds you will need to use water to keep the bit cool. Diamonds work by grinding away with friction and friction produces heat. The matrix material that the diamond chips are imbedded in will glaze over and the bit will become useless if run dry. Diamond core rigs have a water supply feature where you can attach a garden hose to supply the bit with water. If you don't have access to a garden hose we do have a water tank available as well. This is pretty much like a large garden sprayer. You fill it with water and pump it up to pressurize it. Of course when drilling with diamonds the water will form a concrete slime that spreads out from the area so if you are drilling in an area that needs to be somewhat clean it would be handy to have an assistant with a shop vac handy.

Diamond bits are available in sizes up to 10" diameter. They are capable of drilling about 16" deep in one pass until the core bit bottoms out of the stump. If you need to go deeper you simply stop and stick a large screwdriver or small pry bar in the hole and snap off the core plug. You lift out the old stump, add on an extension shank and keep on drilling. Very deep holes can be drilled this way. 

As always, feel free to contact us with your exact situation and we'll be happy to advise you on the best course of action.