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Types of drill
bits for drilling glass:
How you drill the
glass and the type of bit you use depends on the size of the hole
and which type of tool you own. When firing glass in a kiln, the
glass gets
hot enough to actually flow just a little. This means using a larger drill bit than the finished hole size
required. You can use either
a diamond core drill bit on a drill press or you can use a special
blunt-tipped diamond bit made to work in a Dremel or other rotary
tool. I had used both in the past but wanted to study the benefits
of each option.
After drilling more
holes than I want to count, I like the diamond core drill bit on a
drill press. It’s a faster and more precise operation than using a
Dremel. On the other hand, the rotary tool bit works almost as well
and requires only a tool that most of us have around anyway.
Sally Monahan 1/07
Sally says, "Spay and neuter your pets."
Some tips about
drilling glass:
Use a Sharpie
permanent pen to mark where you want to drill.
It’s important to
keep the bit wet and clean during the entire drilling process. It
keeps the bit cool, keeps glass dust from going up your nose and it
adds a little “slip” to the process. Never drill dry glass. Simply
keep water on the piece of glass and occasionally lift the bit out
of the hole to allow the glass dust to move out into the water and
the water to move into the hole. If a paste starts to form while you
are drilling, stop and add water.
When I’m using a
Dremel, I keep a little water nearby and use my fingers to splash it
onto the top of my glass as I drill. When I’m using a drill press, I
like to set the piece of glass I’m drilling onto a rubber mat, then
place that into a large flat dish of water on my drill press table.
In other words, the glass is actually sitting in a shallow pool of
water while I drill.
In both cases
(rotary tool or drill press) you want to use a slow speed and a
steady hand. Always seat the bit all the way into the chuck. It cuts
down on vibration and is safer. Also, it’s better to drill half way
through the glass from one side, flip the glass over and then to
continue drilling from the other side. This helps prevent chipping
the surface of the glass.
The bit for a
rotary tool is shaped sort of like an hourglass. Put some water on
the glass and start the tool’s motor (slow speed). Hold the tool at
about a 15-degree angle and just tap the glass with the edge of the
bit to give yourself a little starter dent. Now lift the tool,
settle in, get comfortable and brace your arms. Start drilling the
hole by moving the tool, at a 15-degree angle, in a slow circular
motion. Continue with the same motion and angle until you are about
half way through the glass.
Turn the glass over
and start again from the other side. I suggest that you dry the
glass and mark it again. The parallax caused by the water and also
by the beveled glass will visually distort the hole’s placement. The
goal is to have the 2 halves of the hole meet in the middle. When
you first break through, the hole will be a little misshapen. If you
look at the bit you’ll see that its “shoulder” is also encrusted in
diamonds. Very gently, with no pressure at all, run the bit all the
way through the glass so that the shoulder of the bit can clean out
the hole and make it into a neat and tidy round shape.
To use a diamond
core bit in a drill press, the process is similar. Place a shallow
dish of water on the drill press stand. Set something into the dish
to set the glass on. This should be something that isn’t slippery
and that you don’t mind damaging.
Again, seat the bit well into the drill’s chuck. Use
a slow speed and a firm hand while drilling. Do not push the drill
bit through the glass. Let the bit grind the glass away. The diamond
core bit will leave a little cylinder of glass after its work is
done. Be sure to remove this from the dish or you may scratch the
bevel while drilling subsequent holes. Again, parallax will cause
alignment problems so take your time when exiting and re-entering
the holes.
Carole Lamb 1/07 |
Two types of drill
bits: The one on the left is used with a hand rotary tool. The bit on the
right is used in a drill press.
(Both
bits are available from Volcano Arts)
Using a Dremel, you
rotate the bit at a 15% angle. It's easier than it sounds.
Water is a lubricant and keeps you from breathing ground glass
My set up for drilling with a drill press
Mark holes with a permanent pen and then be sure to allow for
parallax when lining up the bit and the marks |
