Cutting acrylic isn’t always easy. If you’re not careful, you may end up with an edge that looks less professional than you’d like. This is especially true if you aren’t aware of the difference between extruded acrylic and cast acrylic.The two do cut differently, so it’s important to understand what you need to do to cut both. These six tips will help you make sure you get the best edge possible.
1. Make Sure Your Machine is Configured Correctly
If you haven’t set up your machine correctly, it’s not going to cut right. You will ideally use a CNC router to cut acrylic, and there are a number of these machines on the market. You want to be certain that you select a solution that offers a strong base, a smooth drive system, and a powerful vacuum system to hold the materials down. You will want to make sure you understand your end goal and set the correct settings for the texture, thickness, and other variables in your materials.
2. Select the Right Material
What material does your project require? For working with acrylic, many professionals recommend extruded acrylic over cast acrylic when finishing with a laser. While laser cutting extruded acrylic, you get a polished edge while you cut, eliminating the need for extra steps. Cast acrylic tends to be more expensive than extruded as well. however, if you’re routing acrylic, you’d likely prefer to use cast acrylic.
3. Select the Right Collet
A number of CNC router operators don’t change their collets out for years, and that can cause issues with the cut. After about six months, your collet may no longer hold the router bit perfectly straight, and that can affect the cut. Make sure you’re using the correct collet for your spindle and that it’s not worn down. It’s often hard to visually see when a collet is wearing down, so don’t always trust a quick visual inspection.
4. Select the Right Tool
Are you using the right tool for cutting acrylic? CNC routers have dozens of different options, so you want to be sure you have the right one installed. For acrylic, you’ll want to use a single flute, upward spiral router bit. This bit offers finishes that are smooth and consistent. When selecting your tool, you want to pick the one that is long enough to cut through the acrylic but isn’t any longer. This will reduce the amount of chatter and cutter deflection that occurs.
5. Position the Tool
Besides using the right tool, you also need to make sure that it’s positioned correctly in the collet. The cutting flutes should not be within the collet, and a small amount of the shank should also be exposed to allow the machine to cut correctly.
6. Use the Right Cutting Process
When cutting acrylic, you want to make sure you use the right cutting process. The first thing to decide is the RPM setting. How fast your cutter is going will determine the finish. For cast acrylic, you want an RPM of at least 32,000. This will ensure that the finish is clear and smooth. If your spindle has a max RPM that’s lower than this, you will need to polish the acrylic once you’ve cut it. You can use a polishing bit to achieve this. Polishing bits can operate between 16,000 and 18,000 RPM.
When you’re feeding acrylic into the router, you should not exceed 300 inches per minute. Your bit diameter will determine how quickly you feed the material to the router. A 1/8” bit cannot exceed 100 inches per minute, while a 1/2” bit can handle spends as fast as 300.
When cutting to extract large portions of material, you don’t want to exceed the width of the bit in pass depth. If you are using a 6mm bit and have 12mm of material to cut, it will require two passes. You may need to use the polishing bit if you’re using thicker material that requires multiple passes. Alternatively, you may choose to step the first passes out 1mm and finish the cut in one pass at true size so the passes aren’t visible on the finished edge.
Finally, you want to make sure that your router has been deionized before you start cutting. That’s because the dust and other debris from acrylic has a strong static charge. It will stick to your materials and your router. If you have a deionizing unit on your router, that will help to neutralize the charge. Then your dust collector can remove the dust without any problem.
Learn Your Machine and Your Materials
As with any tool, it takes some time to get perfect results with a CNC router. You need to learn the equipment and its various tools and options. Once you’ve gotten used to how you determine RPM, depth, the right tool, and other factors, you’ll find that cutting acrylic and other materials isn’t that difficult. It takes a little bit of practice and an understanding of tips such as those discussed above.