DIY 3D Tech

The On-Line Magazine for 3D Printing & CNC

CNC Tips and Tricks – Cutting Extruded Polystyrene Sheets

So in this episode we are going to look at machining sheets of extruded polystyrene sheets we bought a  couple years back.  This was very cheap verses that of acrylic, however machining is a bit harder as the plastic wants to melt rather than cut.  So what we did was:

1. Use a 1/8″ 2 flute end mill (

2. Kicked the speed up to 100 Inches per minute

3. Slowed the spindle down to only 1/3 speed using a speed controller(


A. Polystyrene

 is a synthetic aromatic polymer made from the monomer styrene. Polystyrene can be solid or foamed. General purpose polystyrene is clear, hard, and rather brittle. It is an inexpensive resin per unit weight. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants.

As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behavior is exploited for extrusion, and also for molding and vacuum forming, since it can be cast into molds with fine detail.

B. Polystyrene features

  •  Excellent light transmittance.
  •  High mechanical strength.
  •  Weather proof
  •  Non-toxic and chemical resistant.
  •  Easily be processed

C. Polystyrene applications

  •  Advertisement: blow molding board, CNC engraving materials, Laser engraving materials, sign board,  light box,  window, logo and mark, etc.
  •  Furniture: office furniture, cabinet, window, etc.
  •  Finishing Material: decorative sheets, storage racks, room segments, etc.

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