We had a concrete slab laid for the patio as we're going to be tiling it, but in a few places, the concrete is too high by between 5-10mm concrete grinding jacksonville. The total problem area is probably 3-4m2. What would be the best/easiest/most cost-effective way of getting it back to the right level? I've looked at concrete grinding machines but they look like overkill for what we need. Would a cup grinder do the job and can I just fit it into a cordless drill?