I'm in need to buy a rotary hammer to make some holes in a slab about 12 cm thick of armed concrete. The holes will be between 5 and 10 cm in diameter, so I will have to hammer a round opening instead of drilling through (or drill lots of holes in a circle).
The rotary hammers in the market goes from 2,5 to 30J. I have no idea of how much energy I need to this task and I wasn't able to find it anywhere. The price goes up really high (and so is the weight of the tool).
The smaller models (about 2,7J) like Bosch GBH 2-24 costs about 7 days of rental of a bigger model (about 10J), so I'm inclined to buy one if it will work.