Drilling a hole in an acrylic sheet requires a specialised drill bit or a high-speed metal drill bit modified to drill through acrylic without chipping or crazing the acrylic sheet. To modify a high-speed drill bit, you need to change the way the drill bit removes the material from the hole you are drilling. A high-speed drill bit gouges material as it drills, which can chip and damage the acrylic sheet. Correctly modifying the drill bit with a grinder will convert the drill bit from a gouging action to a grinding action.
Put on your safety glasses, turn on the bench grinder and fill the bench grinder water basin. If the bench grinder you are using does not have a water basin, set the cup of cold water next to the bench grinder.
Hold the high-speed drill bit in your hand with the tip of the drill bit facing away from you.
Place the tip of the drill bit against the grinder wheel of the bench grinder while holding the drill bit at a 30-degree angle to the face of the grinding wheel.
Rotate the tip of the drill bit along the face of the grinding wheel to grind the tip to a 60-degree angle.
Run one cutting edge of the drill bit along the side of the grinding wheel to decrease the biting capacity of the drill bit. Repeat the procedure on the other cutting edge of the drill bit.
Dip the tip of the drill bit into the cold water to cool it.
Run the back edge of each drill bit flute along the grinding wheel to taper the backside of the drill bit. This will decrease the surface contact between the drill bit and the acrylic sheet, reducing the amount of heat generated during the drilling process.
Dip the drill bit in the cold water to cool it and complete the modification process.