Who suffered, making holes in concrete slab, knows that the best assistant in this case — a power drill. Well, if it does not exist? You will rescue two hammer and carbide drill bit d 4 and 7 mm. First, work a smaller drill bit and lightly hitting it with a hammer and turning a bit after each stroke. Breaking to a depth of 5-10 mm, model drill more and clean the resulting hole. The cycle is then repeated in 20 minutes manages to punch a hole to a depth of 40 mm.
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