How do you core drill granite?

Her's how I did uit . it/s quite different from going through sand stone , limestone or light arieated concrete blocks .

Put a long thin pilot drill through first so the cocr drill pilot can follow the hole right through the wall . Core drill from both sides to get a nice hole one each side . Beware of the core drill pilot drill coming loose and sticking in the hole . ( Even using brand new parts from Screw Fix )

Don't let the SDS hang by its weight on the drill bit adaptor at the chuck end they are very thin and they break far too easily if you do .

On a hired bit & drill the core drill kept coming loose I had to separate the core drill and the holder and clean them up for an hour or more to remove deep scores & ridges on the contact faces as the drill would not seat in the adaptor properly . Used water & medium wet & dry before the core pilot drill would stick in the holder .

Make sure your SDS has a slow speed & a clutch , don't use hammer , let the drill do the work don't try to force it into the granite , a light gentle pressure is best , keep bringing the core drill in & out and vacuum out the dust / crud if possible .

If the wall is infilled with rubble be aware that lumps often fall down behind the back face of the core drill making extraction difficult to say the least.

Had to disconnect the SDS and pop on a long 10 mm drill bit to drill into the fallen stone first then drill on hammer the chunks to break down stones that had fallen down stopping me pulling the core drill out . On thick walls I used a 15 inch long round drift punch made from high carbon steel to put in the core drills pilot hole every two to three inches and give it a firm but not heavy tap with a small lump hammer to split the column/core of stone that formed as the cutter bit into the stone . After a while if you don't remove this island of stone your core drill rear end will rub on it and you cant drill any deeper .

This time last year I put a 76 mm hole through a heavy concrete cavit block wall for my mancupboard heater , and a 35 mm hole for eh air intake for he burner and another the same size for the exhast pipeHer's how I did uit . it/s quite different from going through sand stone , limestone or light arieated concrete blocks .Put a long thin pilot drill through first so the cocr drill pilot can follow the hole right through the wall . Core drill from both sides to get a nice hole one each side . Beware of the core drill pilot drill coming loose and sticking in the hole . ( Even using brand new parts from Screw Fix )Don't let the SDS hang by its weight on the drill bit adaptor at the chuck end they are very thin and they break far too easily if you do .On a hired bit & drill the core drill kept coming loose I had to separate the core drill and the holder and clean them up for an hour or more to remove deep scores & ridges on the contact faces as the drill would not seat in the adaptor properly . Used water & medium wet & dry before the core pilot drill would stick in the holder .If the wall is infilled with rubble be aware that lumps often fall down behind the back face of the core drill making extraction difficult to say the least.Had to disconnect the SDS and pop on a long 10 mm drill bit to drill into the fallen stone first then drill on hammer the chunks to break down stones that had fallen down stopping me pulling the core drill out . On thick walls I used a 15 inch long round drift punch made from high carbon steel to put in the core drills pilot hole every two to three inches and give it a firm but not heavy tap with a small lump hammer to split the column/core of stone that formed as the cutter bit into the stone . After a while if you don't remove this island of stone your core drill rear end will rub on it and you cant drill any deeper .

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