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Thread: Cutting Acrylic Plastic

  1. #1

    Cutting Acrylic Plastic

    How do you cut acrylic plastic sheets? Yes, I know I can use carbide bits on my router to shape the edges, I'm trying to cut big sheets into smaller ones. Thank you.


  2. #2
    Join Date
    Jul 2008
    Alexandria, Virginia
    How To Cut Acrylic Plastic Sheet

    Cutting with a knife or scriber Acrylic sheet up to 3/16" thick may be cut by a method similar to that used to cut glass. Use a scribing knife, a metal scriber, an awl, or a utility knife to score the sheet. Draw the scriber several times (7 or 8 times for a 3/16" 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 a 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.

    Table and circular saws Use hollow ground high speed blades with no set and at least 5 teeth per inch. Carbide tipped blades with a triple chip tooth will give the smoothest cuts. Set the blade height about 1/8" above the height of the material. This will reduce edge chipping. When using a hand held circular saw, clamp the sheet to the work surface and use a length of 1x3 wood to distribute the clamping pressure and act as a guide for the saw.

    Feed the work slowly and smoothly. Lubricate the blade with soap or beeswax to minimize gumming from the masking adhesive. Be sure the saw is up to full speed before beginning the cut. Water cooling the blade is suggested for thicknesses over 1/4", especially if edge cementing will be performed.

    Saber 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.

    Routers and shapers Use single fluted bits for inside circle routing and double fluted bits for edge routing. At the high speeds at which routers operate it is critical to avoid all vibration. Even small vibrations can cause crazing and fractures during routing.

    Drilling Acrylic Plastic

    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 a scraping action. If the drill is correctly sharpened and operated at the correct speed, two continuous spiral ribbons will emerge from the hole.

    Finishing Acrylic Plastic

    Scraping The first step in getting a finished edge is scraping. The back of a hacksaw blade is perfect for scraping. Simply draw the corner of the square edge of the blade along the edge of the acrylic. Filing A 10 to 12 inch smooth cut file is recommended for filing edges and removing tool marks. File only in one direction. Keep the teeth flat on the surface, but let the file slide at an angle to avoid putting grooves in the work. Sanding If necessary, start with 120 grit sandpaper, used dry. Then switch to a 220 grit paper, dry. Finish with a 400 grit wet/dry paper, used wet. Grits as fine as 600 may be used. Always use a wooden or rubber sanding block. When removing scratches be sure to sand an area larger than the scratch. Sand with a circular motion, and use a light touch and plenty of water with wet/dry papers.

    Almost any commercial power sander can be used with acrylic. Use light pressure and slower speeds.

    Polishing Final polishing will give acrylic a high luster. Power-driven buffing tools are recommended without exception. Buffing wheels are available as attachments for electric drills. A good buffing wheel for acrylic consists of layers of 3/16" carbonized felt, or layers of unbleached muslin laid together to form a wheel. Solidly stitched wheels should be avoided.
    The wheel should reach a surface speed of at least 1200 feet per minute. Speeds of up to 4000 feet per minute are useful for acrylic.

    Acrylic should be polished using a commercial buffing compound of the type used for silver or brass, or you can use a non- silicone car polish that has no cleaning solvents in it.

    First, however, tallow should be applied to the wheel as a base for the buffing compound. Just touch the tallow stick to the spinning wheel, and then quickly apply the buffing compound.

    To polish, move the piece back and forth across the buffing wheel. Be careful not to apply too much pressure. Keep the work constantly moving to prevent heat buildup.

    Never begin polishing at the edge of the sheet. The wheel could easily catch the top edge and throw the piece across the room or at you.

  3. #3
    Join Date
    Jan 2009
    I live in Denton, Texas and ranched at Schulenburg, Texas.
    This is an excellent compliation. I think it covers the subject completely and concisely.
    The only add-on I have is if you have an old fine tooth HSS plwood blade; it works great with various plastics. I like to score the plastic first, then I raise the blade to cut. We owe Frank a hooraha for his help

    Ray Gerdes in beautiful Texas
    Last edited by Raymond Gerdes; 02-08-2009 at 09:36 PM. Reason: error

  4. #4
    Quote Originally Posted by Raymond Gerdes View Post
    if you have an old fine tooth HSS plywood blade; it works great with various plastics. I like to score the plastic first, then I raise the blade to cut.

    Ray Gerdes in beautiful Texas
    I used to have them, now I only use carbide blades. Are they still available?


  5. #5
    Quote Originally Posted by Dietrich Trenner View Post
    I used to have them, now I only use carbide blades. Are they still available?
    After reading the post about old plywood blades I went to my shop and found an old Sears plywood blade that I hadn't used in 30 years. It worked like a charm on my acrylic. Thanks a million for the suggestion.


  6. #6
    Join Date
    Nov 2008
    The Couv, Washington
    I recently cut some 1/4 inch acrylic with my Steel City 40 tooth. I didnt have a blade with a higher tooth count so I used what I had. Worked just fine.
    We put the "k" in "kwality."

    The above picture is not me!!

  7. #7
    Join Date
    Jul 2008
    Alexandria, Virginia
    My pleasure. The 'issues' I've had with using a table saw was with melting the edge. I usually cut a little big and trim with the router.

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