I am building a garden room and wanted to use 7.5mm concrete screws to hold it to the concrete base but I have tried 3 6mm masonry drill bits and all have blunted after 1 hole using my hammer drill. Is there a special drill bit I should be using or any tricks I am missing?
Is it the drill bit or just an under powered drill? My Makita cordless is top notch but will struggle in concrete, for that I get the SDS+ drill out and it eats concrete like a knife through butter. What drill are you using?
Dewalt extreme masonry drill bits. Don't go too fast as there is an optimum speed for drilling and that's not fast or it rattles over and just gets hot..
Are you definitely using masonry bits? Masonry bits aren't really sharp to start with, so you can't really blunt them. Certainly not after 1 hole. If they are masonry bits, then make sure your drill is set to hammer and apply lots of pressure.
thanks all. So I am using a mains powered Makita hammer drill and used a carbide tipped masonry bit. I am guessing I may have hit a stone in the concrete as it showed heat discolouration at the tip.
You're probably hitting a steel reinforcement bar in the concrete. Masonry bits will not drill through them.