CNC Acrylic Letters

If you like this project, why not check out my open source Bluetooth Low Energy Color Sensor at!

Over the Christmas break I decided to put my new CNC to work by cutting out a clear acrylic letter for my mom. I used CamBam to make the toolpaths and the G-code that was then sent to the CNC. After the acrylic was cut out, the edges become translucent or “frosted”. The edge was quite consistent so some people might like this look and choose to leave it as is. I wanted a transparent look so I had to finish the edge with a map gas blow torch, that burns at approximately 3,600 degrees Fahrenheit (Propane = 3,450 degrees Fahrenheit) . A quick “brushing” motion with the flame will melt a very thin layer of acrylic on the edge and thus make the acrylic clear again. This technique is known as flame polishing. You can see pictures and video of the entire process below.

The raw G-code is on the left monitor and a simulation of the job is on the right monitor

You can see the letter ‘L’ being cut out above. Notice the large amount of acrylic dust… Don’t breathe this!

[youtube clip="9oxC5UmOzRg"]

Here is a video of the cutting process. The acrylic is 3/4 inch thick and the CNC is machining away 0.4mm per pass. The entire cutting process took around 15mins.

Flame polishing is fun :)

The finished product!