Is it necessary to cut a specific shape from an acrylic sheet. If so, it is better to mill the acrylic sheet than to saw it. When professional edge finishing and complex shapes are needed, milling is the best method. Our 6 tips will make milling perspex easy with standard DIY tools.

For milling acrylic sheets:

• Router with variable speed
• Router with 1 HSS cutting edge (hardened steel) – different diameters
• Support panel (wood)
• Supporting battens
• Safety glasses
• Vices and glue clamps

#1. Cast acrylic sheet is best

It is possible to mill cast as well as extruded acrylic sheets. When milling perspex, however, it is strongly recommended that you use cast acrylic sheets. Extruded acrylic is more susceptible to breaking because of its internal stresses. Cast acrylic glass is easier to machine, and should be preferred for milling.

#2. Choose the right tool for milling PMMA

Professional clear plastic sheet converters use machines that have a large bed to properly support the sheet material. These CNC (Computer Numerical Control), devices clamp the acrylic sheet in a milling machine, and then process it with a multi-axis computer-controlled milling cutter. It’s also possible to rout perspex with regular DIY tools such as a router or wood milling machine.

It is important to ensure that your milling machine’s blade is sharp and that the cutter doesn’t become clogged with chips. We recommend that you use a vacuum connection on your milling machine. You will create many chips when you start milling. Wearing safety glasses when milling is a smart precaution.

#3. Adjust the cutter diameter to the thickness of the acrylic sheet

Choose the right cutter by using cutters that have a carbide cutting edge (HSS). How can you determine the right diameter cutter? Consult our handy guide below.

Acrylic sheet thickness Cutter diameter

2-5 mm 4 mm

6-10 mm 6 mm

10 mm or more 8 mm – 10 mm

Tip: Use a faster speed for smaller cutters than thicker blades. Start by milling scrap material.

#4. During milling, support the acrylic sheet as well as the cutter.

During milling, both the panel and cutter must be supported. Place the acrylic sheet on a stable surface to prevent it from vibrating while milling. A wooden board is ideal for this purpose. Also, the top of your sheet must be supported. The acrylic sheet should be pressed against the solid surface. This can be done with battens, screw clamps, or vices that support your panel along the milling lines. You can also run the cutter along a straight line if you prefer straight milling lines.

#5. Mill your perspex in several stages

It may be necessary to mill your acrylic sheet multiple times depending on its thickness. Thin sheets less than 5 millimetres in thickness are exempted from this rule. These acrylic sheets can be machined in one pass. These thinner sheets should be milled in the opposite direction to the cutter’s rotation. This will give you a cleaner edge than down milling.

You can mill thicker sheets in multiple stages. Two passes are required for sheets up to 10mm thick. For thicker sheets, you will need to mill in four steps. Although you may think the sheet can be milled in just three passes, we recommend milling in four stages. The fourth pass is the best time to slow down your mill and use a slower throughput speed. This creates the most beautiful edge finish.

#6. Polish the edges of your acrylic sheet

You can polish your perspex sheet’s milled edges to create a more elegant and smoother finish. Learn how to polish acrylic.

What can you make with acrylic milling?

You can create any shape you like from perspex sheets once you have started milling. Acrylic can be used to make circles, squares, numbers, and other shapes. Examples of commonly seen examples include the perspex signs and advertising letters made from milled acrylic letters.