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Realistic rocks drilling

Is it realistic to think a half inch to one inch deep hole could be
drilled into a stone? (probably granite). A friend has two heart
shaped stones (I am talking rocks) approximately 5 inches in diamater
and she would like to fasten them to the back of a box that would sit
upright. Epoxy by itself would not do it, so I wondered if a hole
could be drilled and a peg epoxied into it to give it support when
suspended. I have read that a diamond bit could be used, but just any
diamond bit? In a flex shaft? In a drill press? Under water? Or is
this more the task of a professional lapidary?

Thanks, Jackie Richards

Is it realistic to think a half inch to one inch deep hole could
be drilled into a stone? (probably granite). 

Most lapidary drills that size are core drills. That wouldn’t help
in this case unless you wanted to chisel out the stone left by the
core drill. I know there are drills for such an operation but I can’t
find them from my usual list of suspects… I mean suppliers. If you
could find one it would probably be pricey ($100 or more). And you
would have to use a drill press and water drip.

What I would suggest is using diamond carving bits. They sell cheap
imported sets on eBay for pretty cheap. Any way, they have some bits
that are about 1/8" in diameter and flat on the bottom. I would
suggest drilling 2-3 holes in each stone then gluing 1/8" dowels or
1/8" steel pins into each stone and mount it that way.

Be sure to use a water drip and drill slowly and pull the bit out
often to let the hole flush with water or you will heat up the bit
and the diamonds will be gone.

Rick Copeland
President Colorado Springs Mineralogical Society
Silversmith and Lapidary Artisan
Rocky Mountain Wonders
Colorado Springs, Colorado

Is it realistic to think a half inch to one inch deep hole could
be drilled into a stone? (probably granite). 

This is how I’ve drilled holes in different rocks althoush I have not
drilled a hole that large or deep. I would imagine you would use a
larger bit. Use a blunt drill bit with diamond grit bonded to the tip
in a rotary tool with an adjustable speed control will work. Do not
use a three-jaw chuck to hold the drill bits. Use collets sized to
fit the drill bit. Place rock in water to cover for cooling so you
are drilling under water. Start with your slowest speed and adjust up
until you burn up a bit. Now you have found the maximum speed for
cutting that stone. Start your holes with the blunt end held at about
a 45-degree angle to the surface. Once the hole is started, you can
drill 90-degree straight down. Slowly rotate the drill around in a
circle. Continue this circular motion until the hole is finished.

Hi Jackie

No not a task for a professional Lapidary, but it might be more
expensive than you want if you don’t use the items often. Yes, pretty
much any diamond or Carbide coated bit would work. Just remember
drilling stone is pretty slow and you can’t use a lot of pressure.
When drilling rock, I have found it better to lift the bit from the
bottom of the work often to let water in and sludge out.

A hand electric drill or drill press may be used, I would use a
hollow core bit for a 1/2 or 1 inch hole, but as you did not say how
thick these items were, I am only guessing they are thick enough to
drill into and break the core out with damage to the hearts. Yes, you
will need a supply of water when you are drilling, otherwise you will
destroy the bit and have to buy more.

Alternate suggestion - Drill smaller holes around the edge, and use
a threaded screw, like a 6 or 8 and drill in 1/2 inch and epoxy, you
could get by with a much smaller bit, but you will have to drill more
holes, but then you could just bolt it on to the box.

Last suggestion - If the stones are that large make a
copper/nickel/brass bezel and drill in from the sides in a couple of
locations and you could use pins to hold it in making a stronger
mechanical bond and less reliance on glue. The copper plate could be
attached to the box by any number of means and the hearts set in.

Sounds like an interesting project, good luck to you and your


Core drills that size are available at Get a
good one rather than the cheap ones. Saves a lot of headaches and you
can use it to cut stone (read) agate/jade rings later or just make
some great round stones.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry!

Many home owner drills have a setting for drilling concrete or stone.
This is called hammer drilling. This and a 1/4 or 3/8 in. carbide
masonary drill bit would be a good choice. A larger hammer drill will
do the work faster but with a greater possibility of fracturing the
stone. So use a smaller less powerful drill motor.

Then a wooden dowell can be placed in the hole. A wood screw can be
used to hold the rocks. This is an old fashoned, low tech way of
doing this. You might try drilling without the hammering action
first. This will be a more gentle approach.


Hi Jackie

It’s not too difficult to drill a hole in a rock with a diamond

You do want to use a flex shaft because you do need to use water and
it’s the safest way outside of using a belt drive. Some use Dental
drills, but a flex shaft is fine. It’s good to place it in a holder
of some sort. I use an unmounted vise and position the head at a 45
deg. angle.

For water I use a drip, but a pan is okay. Of course you only
immerse the drill bit and stone. If you use a drip you want the water
to drip into the hole you are forming. If you use a pan, just keep
dipping the stone into the water frequently to keep the drill lubed
and cool. The right way is to apply even steady pressure in the bit
and drill straight in. Start off slow until the drill bites, then
increase speed but not pressure. Keep your pressure light, letting
the drill bit do the work. Once you get about half-way or nearly all
the way through the stone, start drilling from the other side. This
prevents blowout.

Now the wrong way is to use the drill as a grinder and rotate the
stone, both circularly and with the wrist. But that’s the method I
use. It is aggressive, but kills bits. A good bit should last for
quite a few holes even if abused. That’s over six inches of drilling

It just takes time.

One note, when starting the hole, hold the stone firm. You don’t
want the drill to wander across the face making a scar.

Good luck. It is a realistic endeavor. Practice first and it will be
just fine.

TL Goodwin, Lapidarian Metalsmith

If they are any type of rock that is softer than a 9 (carbide) on
the Mho’s scale you can head to the hardware store and pick up a
concrete carbide tip drill bit. They come in sizes from 1/8" up. If
you have a drill press so much the better a plastic pan filled with
water to cover the stone. Mostly to keep the dust down. You probably
wouldn’t need a 1/2 inch peg to hold the stone up with a good epoxy.
Any thing from a couple of 1/8" dia holes to 1/4" would work.

Then use a metal instead of a wood peg, to mount the rock on. The
carbide bits are a lot cheaper, than the diamond bits sold at the
supply houses. And they will with some the addition of some water.
Drill just about most stones out there. I have drilled thru any
number of minerals and marble and granite types.

After all they are using all that kind for the overpriced counter
tops and they have to get a starter hole in them some how for the
sink cut out.

The water will not only keep the dust down but will act as a
coolant. Heat is probably the biggest destroyer of stones when
drilling. Just remember to lift the bit to clean the hole and let
fresh water in often.


This size hole is done commercially If you are only planning to drill
one or two holes in granite I would suggest talking to a local
suppler of granite counter top slabs, perhaps they could be
contracted to drill the holes for you. Or alternatively they could
teach you hoe to do it efficiently.

Wayne M Schenk

Haven’t pitched in on this - it’s a perennial question ;} There is
another alternative, which is the old fashioned way. I guess carbide
is going to do the job, but I’d consider that risky due to vibration
on a nice piece of stone. And diamond is expensive. You can make your
own core drills, though. Get brass or steel tubing of the right size,
solder an end on it and a mandrel, which obviously needs to be on
center, and then you can use carborundum or diamond grit and drill
away… Not as easy as buying one, but much cheaper…