How should a hole be drilled in Plexiglas to avoid damage when the drill breaks through?

• A. Back up the plastic with a piece of wood and feed the drill slowly
• B. Drill from the underside quickly
• C. Use coolant only
• D. Drill with no backing

Answer: (A)

When drilling Plexiglas, the key is to support the material as the drill breaks through and to move the drill slowly. Backing the plastic with a piece of wood provides a solid support for the exit edge, so the material isn’t torn or chipped as the drill breaks through. A slow feed minimizes heat buildup and mechanical stress, reducing the chance of melting, cracking, or ragged edges at the exit. Coolant alone doesn’t address the exit damage, and drilling without backing or from the underside quickly removes the necessary support, increasing the likelihood of break-out damage.