Im going to use some plugs and feathers to split some granite. The plugs say drill a 14mm hole. Is it kinder to the drill to drill something like an 8mm hole first then enlarge it to 14mm in a second pass?

Or doesnt it matter? Drill will be a 1500w 8J Titan SDS if it matters.

Thanks

Ian

It will possibly help the accuracy of the drill to do a pilot hole first and I would have thought it would be “kinder” on the drill too as it has to remove less material with each pass. Just remember to move in and out during the drilling to remove the dust rather than try the full depth in one go.

Wouldn’t you be better off with a diamond hole saw type bit for this sort of thing? Cant imagine you would get too far trying to drill a hole in granite with a standard masonary bit, especially a 14mm one.

Wouldn’t you be better off with a diamond hole saw type bit for this sort of thing? Cant imagine you would get too far trying to drill a hole in granite with a standard masonary bit, especially a 14mm one.

Never tried one of those but a carbide tip masonry bit works. I’ve drilled thousands of holes in all sorts of rock like that.

I’d use a diamond core bit .. in which case a smaller hole (bogger than the guide bit) won’t make any difference… (I’ve done lots using lab equipment) but at home for the taps/pipes I used a small 5mm core tile drill to make a pilot then whatever diameter the pipes needed

However depending how thick/massive this is I’d not think you’ll get anything clean with plugs and feathers as you are breaking crystals not a rock with a grain… I’d be making a starting point of weakness using a diamond bladed cutter (in fact did this today by coincidence with a 2″ thick diorite paving “brick”… then just a cold chisel and lump hammer and it split quite cleanly but that’s far finer grained than a granite.

LOTS and LOTS of Lubricant/coolant