Quite a few people have asked me how I drill my rocks, so I took photos of today's process to share with you.
I recommend drilling softer sedimentary rocks (sandstone, limestone, etc). When scouring the beach for rocks, these tend to be well rounded. Those that are not rounded are probably harder igneous or metamorphic rock and are likely to break apart while drilling or break your drill bit.
Pointed masonry drill bit or a hollow, diamond-tipped coring bit. For drilling holes in smaller stones used in jewelry, a 2.5mm diameter bit is a good size.
Plastic container to hold water so you can drill your stone under water (I use an old dog bowl). Drilling underwater cools off the bit and which will speed up your drilling and keep your stone from over heating.
Adjustable wrench to hold your rock in place while drilling.
Small sedimentary rocks
1. Put on your goggles.
2. Using your wrench, firmly hold a rock inside your container, just beneath the water. This takes some practice. My rocks kept popping out at first, but I've since learned how to hold them steady.
3. Turn on the rotary tool and hold it perpendicular to the rock. Press firmly but gently. Do NOT rotate the hand holding the rock or else the rock will crack. The water will become cloudy, but that's fine. Continue to push firmly until the bit pokes through the other side.
That's it! You may choose to throw your rocks into a tumbler, but I prefer the raw, rough look.