Use diamond bits to drill hard, brittle materials like glass, ceramics and stone. Drill holes using a round ball shaped bit. First, pick the shank size that fits your tool, and then choose a round ball shaped bit that matches the hole you need.
Diamond bits (even coarse) will leave a smoother finish than spade bits or twist drills and won't chip and crack your work. With a little luck, the finish will be smooth enough, without any additional polishing. Drill speeds vary. Start out slowly and gradually increase the speed. The larger bit, the slower you should start. The more lubrication you use, the faster you can drill.
Drilling faster increases friction, burns up the bit and causes and causes the colorful drill tips. Everyone repeat after me: if your drill bit develops yellow, brown, blue or black “burn marks” around the tip, slow down.
Increasing the pressure on twist drills makes the bit drill faster. Not such a good idea with diamond bits. When you use diamond drill bits it is very important to use light to moderate pressure and to let the bit "drill at its own speed".
Increasing the drill pressure will only increase the friction and heat. This not only burns up the bit, but also increases your stress level, causing your face to turn red and steam to come out of your ears. Heat will also fracture or crack the material you're drilling. Again, everyone repeat after me; if your drill bit develops yellow, brown, blue or black “burn marks” around the tip slow down and lighten up.
If you are dilling a hole completely through an object, it is important to "lighten up" the pressure even more when the drill bit is about to break through. This reduces chipping on the backside of the object when the bit emerges from the back.
Better yet drill half way through, flip the material over, start a new hole on the backside and let them meet in the middle. Yes, I know this is "easier said than done". I have plenty of glass with holes that didn't quite match in the middle. It must be a faulty measuring tape!
Lets start out with the legal stuff first. Please be careful using any electrically powered tool near water. Water or another lubricant should be used to cool and lubricate the tip of diamond bits. Lubrication reduces heat build-up, sort of like adding a little cold water to hot coffee to cool it. Water is usually used, because it is cheap and available.
Increase the amount of lubrication used with harder materials. If you are drilling fiberglass, a diamond bit can be used dry or with a very small amount of water. When drilling in glass, ceramics, or stone use enough water so that the “dust” from the hole is a very wet paste or wetter. The tip of the drill bit should always be wet. If you are drilling hard or abrasive material, use even more lubrication. If you can, have a small amount of lubricant constantly running over the drill tip and bore hole.
A Few Tips: Use a small hose or tube to run water onto the surface near the drill tip and bore hole. Some people place a plastic jug (milk jug) with a small hole near the bottom of it, next to the drill hole. As the water leaks out of the bottle, it provides continuous lubrication as you drill.
Another trick is to build a "dam" around the drill hole using modeling clay. Fill it with lubricant.
Or, place the object being drilled into a shallow pan or tray then fill the pan with enough water to just cover the material. Don't make my mistake. Place a thin board or Styrofoam in the bottom of the pan or you will drill right through the pan bottom making a mess and causing you to wonder why you thought this was a good idea.
If you are drilling on a vertical surface use a hose or tube to run water to the drill tip. If that's not possible, have someone "mist" water onto the drill tip using a squirt bottle. (More legal stuff) Please be careful and use common sense around water if your tool is electrically powered.
Unfortunately learning to balance drill speed, drill pressure, lubrication and your time is a learned skill. Learned from trial and error. It is best to start out with a very slow drill speed, very light pressure and lots of lubrication. Gradually increase all three until you reach the point where time spent drilling balances against the cost of more drill bits. Starting slow reduces risks and extends bit life. Always use more lubrication than you think you need.
Your choices include diamond bits in several different grits, Extra Fine, Fine, Medium, Coarse and Super Coarse. These are all relative terms. How fine is Fine? How coarse is coarse. Most people are familiar with sandpaper so we've compared international standards for diamond tools to common sandpaper grit. The table below compares diamond grit to sandpaper grit:
Extra Fine diamond grit is comparable to 360 grit sandpaper.
Fine diamond grit is comparable to 200 grit sandpaper.
Medium diamond grit is comparable to 120 grit sandpaper.
Coarse diamond grit is comparable to 95 grit sandpaper.
Super Coarse diamond grit is comparable to 75 grit sandpaper.
We hope this helps. Most people will not see or notice a significant difference between medium and coarse grit diamond tools. For most applications we recommend that you order the coarser grit.
The best way to prevent the bit from skipping or walking when you're starting a hole is to use a drill press. This holds the bit firmly in place. Use a vise or some other system to hold your work firmly in place under the drill press.
If you can't use a drill press, keep the bit from walking or skipping by making a pilot hole in a piece of wood or plastic using the diamond drill or another bit. 1/8" thick wood, 1/8" Plexiglas or even cardboard will work. Place this "template board" on the material being drilled, with the pilot hole above your target spot. This will keep the diamond bit centered in place while you start the hole with your hand drill or rotary tool.
This is the question our customers ask most often and the one we can't answer.
The hardness and abrasiveness of the material being drilled, the tool speed, the pressure used and the amount and type of lubrication affect the life span of all diamond bits, ours and all others. Even materials that appear similar have varying degrees of hardness and abrasiveness. It is impossible to estimate the life of a diamond bit. On some thin, soft materials a diamond bit may last for 50-100 holes or more, while on some thick, very hard or very abrasive materials the life many be only 1-3 holes or less.