Drilling deep hole in Granite, is it possible?

[Perry Holbrook]

I'm creating a landscaping project that involves using granite boulders as fountain heads. Basically I want 3 boulders, 36",24",18" tall with a 1" hole drilled top to bottom. Through this hole water and fiber optic lighting cable will pass.
Creating the hole has become a challenge. So far I can't find anything that is designed for this, except for very heavy and expensive tooling.
Anybody ever tried doing this or have any ideas?

Thanks

[Tom M King]

There are long SDS-Max drill bits. I have one 3' long one that I think is 1-1/4" for 1" PVC pipe to pass through. I wouldn't want to do it will any drill smaller than an SDS-Max.

A 1" bit in such a drill will walk right on down through Granite.

To get through the 3' rock, you'll need a 48" bit. Google found many: https://www.toolsboltsnbits.com/shopping/bits-and-accessories-c-14/bits-c-14_34/sds-max-bits-c-14_34_90/?sort=20a&page=4&zenid=4t9d1p9us8vi3c1uktspv53ts7

Looks like about $250.

If you could make a 36" bit work, they're a lot cheaper: https://www.amazon.com/HC5073-SDS-Max-Speed-X-Concrete-Drilling/dp/B0009H5T5A/ref=sr_1_7?crid=1KPRF04EBCBJO&keywords=1%2Bsds%2Bmax%2Bmasonry%2Bbit&qid=1676664944&s=industrial&sprefix=1%22%2Bsds%2Bm%2Cindustrial%2C76&sr=1-7&th=1

[Perry Holbrook]

Tom, are you sure that bit will do the job? Don't mean to question your respected knowledge. I just came from my local rental store who has those bits with drills but they didn't think they would work in granite. They called Makita who said their bits were not for granite. But if you have actually done it, that carries much more weight.
Thanks

[Tom M King]

We have an abandoned Granite quarry on our place. I've built granite fireplaces in most of the spec houses I've built. I can't count the number of holes I've drilled in Granite. Our granite is the kind tombstones are made from. Any SDS-Max bit I've ever used will walk right on down through Granite. Even back before SDS-Max drills, I had a spline drive drill that did the granite drilling jobs.

To cut large stones of granite into smaller stones, you have to drill a bunch of holes and use wedges and shims (also called feathers) to split it.

I don't believe anyone from Makita would not think their bits would drill Granite. When you drill through concrete, you are also drilling through a lot of granite-maybe more than half. Granite is used for aggregate around here.

I know I have some Bosch bits and some Freud bits much like the ones in the links I posted, but don't know the other brands. One bit will drill your three holes and still have plenty of life in it.

https://www.youtube.com/watch?v=sarfIojai2I (He would have done better with larger holes and larger wedges and feathers for that size rock)

This guy uses larger wedges:
https://www.youtube.com/watch?v=cBMcMGBhUVk&t=117s I don't imagine he used anything but an SDS-Max to drill the holes.

You can also do curves. On my to-do list is making a better firepit for a rental house. We have plenty of Granite. https://www.youtube.com/watch?v=bIxOUvVrdb0

Here's how you clean off the holes left from the drill: https://www.youtube.com/watch?v=7GPDcANkfPI

Is the rental drill an SDS-Max handheld drill, or a core drill that uses a different kind of bit?

[Perry Holbrook]

Thanks for all this info Tom, it's hard to find a subject that you don't have experience with, :) I'll check out their drill a little closer.

[Bruce Wrenn]

Rent an air compressor and a hand held rock drill. Be sure and wear ear, eye and lung protection!

[Tom M King]

I have a rock drill too, but you need a towable compressor to even run a small one. I can use my 10 hp compressor with 120 gallon tank, but have to wait for it with my 40 pound rock drill. For three holes it's not worth the expense or trouble. For a 1" hole, a big SDS-Max drill is almost as fast. SDS-Max drills come in a range of sizes, but they all use the same bit chuck for the SDS-Max bits. A heavy 15 amp one will hammer harder and drill faster than an 11 amp lighter one. Any of them will do the job though.

I wear foamies in my ears, and earmuffs over my ears. I use water to keep the dust down. The bits don't seem to care whether they're water cooled or not.

[Bill Dufour]

I would drill a pilot hole with a smaller more controlable drill. As deep as possible.
Bill D

[Tom M King]

No need for a pilot hole. The better, faster cutting bits these days have multiple cutters on a mostly flat end even on the smaller bits like 1". They may even have more trouble with a pilot hole.

You will want to be drilling straight down though, so you may need to cobble up a stage to stand on. My old Dewalt drill has a soft start, and is not hard to get it going where you want the hole. It's many times easier to drill a vertical hole than a horizontal one.

Here's a 2-1/2 inch hole I drilled through brick to run a new heat pump line set, a short while back. Some modern bricks seem harder to drill than Granite.

[Allan Dozier]

Ditto on the SDS-Max. I haven't tried it on solid granite but I can attest it goes through concrete like it is warm butter.

[Tom M King]

It will go through Granite about the same speed as concrete, and even faster than through really old concrete.

[Bill Dufour]

My Hilti SDS plus is rated at a half inch hole, 18" per minute, in old concrete.
BilL D

[Steve Christoffers]

New guy here - This is probably understood by most but, you have to keep blowing the dust out of the hole.
Keeps things moving along.

[Bill Dufour]

Dust with air or water.
BillD