Hammer drill. How do they work?

In the Spring I need to remove about an 8"x8" chunk of concrete from the edge of a garage foundation for drainage. Can a "hammer drill" be used to core out some adjacent holes to facilitate knocking this out? How does one work? Does it drill? Or hammer? ..or does it do both at once? If it does both at once, is it hammering while the drill bit is still in place? Or do you alternate a drill bit with some kind of chisel bit? Advise and thanks.
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once?
A hammer drill does just that, twisting and moving up and down slightly at the same time. A rotohammer on the other hand has a position that just hammers, the chisel bit. Chisel bits and rotation could be a recipe for disaster.
I would suggest a bunch of 1/4 inch holes all around the area that you want to remove. Holes almost touching. Then a sledge hammer to break it out. If you drill all the way through the concrete it should come out pretty easily. UNLESS there is steel reinforcement. Might be better to get a cheapy skill saw and a fiber blade(s) and cut as much as you can with that before you do the drilling. The skill saw will do the cutting except in the corners unless you can over cut.
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I had to chisel out some concrete for similar purposes and found an air hammer and straight chisel worked GREAT. it chewed through the concrete like cheesecake! wear GOOD eye protection and cover all open skin cause the flying debris hurts....
I was able to chisel out the area I wanted literally in minutes...and you'll get a feel for it and be able to achieve a nice smooth finish too!!
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BTDT. Won't do it again. Rent a rotohammer and get the job done fast. The standard hammer drill was not designed nor is it heavy enough to do more than an occasional hole in concrete.
Harry K
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I used a rental center's rotohammer with a 1" bit. I had to cut AN ENTIRE doorway into a 12"-thick basement wall back in Massachusetts. One comment: the age of the cement I am told makes a huge difference in the ease of drilling through it, as well as the brittle/breaking you'll see. I drilled perhaps 100-125 holes in a full day and away I went! Worked perfect.
Mark

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