🔍 For acrylic (and other similar plastics like polycarbonate), the best choice is a **single-flute O-flute bit**. SpeTool’s O-flute bits are specifically designed to leave smooth finishes in acrylic, ABS, Nylon, etc.:contentReference[oaicite:82]{index=82}. The single flute clears the plastic chips quickly so they don’t get reheated and melted. Additionally, you want to run the router fast enough feed-wise to keep the chips coming off as nice curls – too slow and the plastic will rub and melt. Generally, a sharp O-flute bit, moderate RPM (e.g. 18k) and a fairly aggressive feed (to keep the chip thick) works well – those thick chips carry heat away, leaving a clean cut. Also, keep the protective film on the acrylic while cutting if possible, it helps prevent chip weld on the surface. Avoid tiny upcut spiral bits meant for wood (they often cause more melting in plastic); the single flute is much better. Many sign makers and front-panel makers use SpeTool’s 1/8\" and 1/4\" O-flute bits to route acrylic shapes or letters with great success: minimal burrs, no melting, and a good edge finish.

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