Machining Guides - Acrylic

Cleaning acrylic

Acrylic is very easy to scratch so wash with a mild soap or detergent, using  lukewarm water, dry with soft cloth or chamois. Grease, oil or tar can be removed with hexane or methylated spirits. Solvent residue should be removed by washing immediately. Do Not Use window cleaning sprays, scouring compounds, acetone, gasoline, benzene, carbon tetrachloride or lacquer thinner.

Cutting acrylic sheets

Cutting with a knife

Acrylic sheet up to 3/16" thick may be cut by a method similar to that used to cut glass. Use a scribing knife, metal scriber, an awl, or utility knife to score the sheet. Draw the scriber several times (7 or 8 times for a 4.5mm sheet) along a straight edge held firmly in place. Then clamp the sheet or hold it rigidly under a straight edge with the scribe mark hanging just over the edge of the table. Apply a sharp downward pressure to break the sheet along the scribe line. Scrape the edges to smooth any sharp corners. This method is not recommended for long breaks or thick material.

Cutting with power saws

Special blades are available to cut acrylic. Otherwise use blades designed to cut aluminum or copper. Teeth should be fine, of the same height, evenly spaced, with little or no set.

Sabre saws

Use metal or plastic cutting blades. The blades you use to cut acrylic should never be used for any other material. Cut at high speed and be sure the saw is at full speed before beginning the cut.

Hand saws

Good results are possible, but very difficult. Be sure the acrylic is clamped to prevent flexing. Flexing at the cut may cause cracking.

Drilling acrylic

For best results, use drill bits designed specifically for acrylic. Regular twist drills can be used, but need modification to keep the blade from grabbing and fracturing the plastic. Modify the bit by grinding small flats onto both cutting edges, so the bit cuts with scraping an action. If the drill is correctly sharpened and operated at the correct speed, two continuous spiral ribbons will emerge from the hole.

Polishing acrylic

If the scratches or machining marks are not too deep, the surface can be polished without prior sanding. Wheels used for surface polishing can be from 150mm to 300mm in diameter, built up to a width of 38mm to 50mm. They are made of soft, bleached muslin for the initial polishing operation and of soft flannel for the final finishing. For the first buffing operation use a medium-coarse polishing compound or a fine compound depending on the depth of the scratches. When polishing the surfaces of the sheet, the piece must be kept in motion at all times. Do not use excessive pressure, as softening from over-heating can result.