# drilling through granite counters



## wstack

Hi All,
I am trying to drill 1 3/8" hole through granite counters. The diamand holesaw does not have a pilot bit and I've been told to use a water ring. I tried gradually starting at an angle and then working the holesaw straight up but had no luck making a clean start. Eventually got it started but does not seem to go through the granite very easy. I went at a slow speed but seems it would take forever to drill several holes. Does anyone have advise on this matter. 
Thank you in advance, wstack


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## firemike

I use a 1/2" board with an 1 3/8" hole in it (use a regular hole saw to cut it) to start it. Once it is 1/8" to 1/4" deep, you can lose the board, the hole saw will stay in by itself. 

Are you using a good grade diamond holesaw? It may have to be "dressed" if the diamonds are getting dull. I generally use a cement block or brick to expose newer sharp diamonds on hole saws or saw blades. A few cuts in the block will wear the resin down exposing fresh diamonds. Keep enough water around the holesaw to prevent a thick paste from forming in the saw cut.


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## wstack

Thanks for the 1/2" trick not sure if its a good holesaw or not, it is yellow but has no name on it and it costs $90. Everyone tells me to drill slow. Im using a 
1/2" Makita drill and just backing off a little. Is this what you would suggest? I know its granite but it seems it should drill through a little bit easier than it is.


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## Rich Turley

Mike is right on with starting the hole and it sounds like you have the right bit. If you keep enough water on it you shouldn't have to go slow. Use plumbers putty to form a dam around the hole to contain water. Use high RPM. I have a bit that goes on a 4 1/2" grinder that will get 10,000 RPM. Goes through like frozen butter.

Rich


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## Mike Finley

When we have slab granite installed for our customers the fabricators cut the multiple faucet holes on site, I've never paid too much attention to what they use, but it is definitly a special stone bit without a pilot bit in it, and it takes them very little time to cut the holes, they don't do anything special to cut them other than one guy drills while the other guy holds a shop vac hose next to the bit to collect the dust since they drill these dry and not wet.


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## firemike

Rich is right. diamond blades need speed to cut (think of the diamond blades on a tile saw or concrete saw). Most drill motors turn rather slow, so it will cut slow. It sounds like you have a decent bit, it just doesn't turn fast enough for "production" cutting, but should work for you if you only have a few holes to drill. also, don't be afraid to put a little pressure on the bit as long as you keep it cooled.


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## wstack

*not working*

OK so first I tried the Makita drill at a slower speed, I got about 1/16-1/8th" deep and the bit broke on me. The place I bought it from exchanged it and said I need to go REALLY slow and keep water on it. "Keep in mind due to no pilot you have to get in maybe an 1/8th inch anyway before you can try removing the wood guide and putting on a water ring". I then took advice from you guys "because it made sense to me". I made a 1 3/8 hole in a board to work as a guide, then drilled into a brick to expose new diamonds, after getting in about 3/16" I removed the wood guide and put on the water ring and drilled at high speed 10,000 rpm w/grinder and applied a little pressure and after about 30 seconds the new bit broke. This got me about 1/2" into the granite "not quite like going through frozen butter". If anyone has any additional advise I'll take it. I would love to know what dry bit someone was using and with what drill/grinder, are you sure they were going through granite? I at this point would doubt they will replace the bit again and am reluctant to say the least to go buy another one.


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## Mike Finley

I think you either have the wrong type of bit or drill. All I see them use is what looks like a beefy hole saw bit with no center bit, I'm pretty sure they are using a 15 year old beat to hell 1/2 drill with the cord duct taped in 3 or 4 places.

How much duct tape do you have on your drill? That might be part of the problem.

If you are really in trouble I can ask my granite rep to find out how they do this. I'm sure it isn't as hard as you are making it on yourself, the guys doing this don't speak much english and they don't seem like they have college educations. Like I said it doesn't take them long to drill 4 holes for a kitchen faucet, it takes them a lot longer to measure and mark them then to actually drill them.


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## Teetorbilt

Geez, what part of 'slow' don't you understand?

Slow to me is about 250-1000 RPM. You have to let the chips flush clear.


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## wstack

Mike, I couldn't agree with you more. It seems like a very simple thing to do. When I cut the granite with a 4" diamand blade on a grinder its very simple. I do however believe that I have the right bit "had the right bit". I even got on the phone with MK maker of alot of tile equiptment and this bit looks exactly like the one they suggest using for granite. The ones made for tile will have a pilot bit. If you have someone to ask it would be much appreciated. I admit all though cracked and split to hell, I have no duct tape on my drill.


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## Mike Finley

Okay, I talked to the granite guys today for you. Are you using a core bit that looks like this?











It's called a DRB01375, made by Alpha. This is what these guys who do my granite fab are using, it is advertised as a bit that you can use wet or dry and will cut through a 3/4 slab in less than 30 seconds. They run them on angle grinders or use an adapter that comes with them and run them on any drill.

Like I said before these guys drill holes in our slabs like it is nothing. They just mark the holes and start going at it. One guy drills and the other guy holds a shop vac to suck up any dust. 

(add some duct tape to your drill or drag it behind your truck for a few miles and then you will look like a pro!):thumbsup:

Hope this helps you out.


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## wstack

Thanks again Mike, this does look just like what I was using except mine is yellow with no name brand on it nor the receipt "maybe a cheap version I don't know". I will definately give one of these a shot. I'll let you know how it works.


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## wstack

OK so I did try the Alpha bit, works like a champ Thanks Mike. Just a side note - the other bit I was using was made by Felker. Although I had no luck with theyre bits, I have to give credit to the company. They sent me two new bits at no charge. The reality is that using the Alpha bit I get through 3/4" in about 60-90 seconds drycut. The Felker you have to use a water ring and it takes about 3-4 minutes. Kind of a shame to steer away from a company that stands behind thier product but in the future I will definately use the drycut bit.


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## KtotheJ

*Awesome Info!*

Thank you wstack for following through with a success story. And thanks for everyone who contributed. Now all I need to do is find some granite to drill though and I'm ready to go. Thanks for making me smarter today.

KJ


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