When getting dry cutting diamond core bits it is important that the cutting segments are laser welded. The silver brazed ones cannot take the heat, especially at high RPM is using a angle grinder or anything that runs at over 1000 RPM. The dry cutting core bits are designed for soft materials like concrete block and brick. For green or reinforced concrete you need a wet core bit. There is a new brand we have been using from Blue Boar (at www.holepro.com) that includes sizes of 2-5/8" and 3-5/8" and cut to a depth of 10" which works more than 90% of the time. They use a standard 5/8"-11 thread so any angle grinder will work and most adapters for SDS drills. With their low cost I figure a per hole cost of around $3.