I am trying to find where i can get a drill bit that will drill a hole into a concrete lintel above a window which is over 60 years old. All the ones i have tried go blunt and wont mark the lintel.
any one can help??
The size and weight of the drill you use has a considerable bearing because of the percussion action. A heavier drill will give a more effective hammer action that will break up the pieces of stone or flint within the concrete. Of course, if you are hitting metal, nothing is likely to work.
I know where your coming from... done this job myself ... building a Conservatory. Chances are, at worst it's steel... or possibly reinforced concrete (with iron bars embedded). I would recommend a diamond drill bit.... buy 2-3 from the likes of screwfix. Of course the weight, power in Joules etc of your drill have a bearing. Have you tried an SDS+ Drill they are incredible at digging into stuff.