April 8th, 2016


At Colorado Plastic Products we use our overhead, 2.5 axis, CNC router for a variety of projects.  This message is to tell you about our router and about some of those projects. First, let’s break the name down of this tool down:

  • A router (in the woodworking sense) is a cutting tool that hollows out an area in the face of a piece of wood or plastic (or metal or foam or fiberglass etc.).
  • Our router is an overhead router, because the cutting tool hangs from an arm on a frame (known as the gantry) and enters and exits the plastic that we are cutting from above the sheet.
  • Our router is referred to as a CNC router because the motors that change the cutting tools location in space are controlled by a computer. Devices such as these have come to be describes as Computer Numerically Controlled devices.
  • The 2.5 axis part of the name means that our router can move extremely accurately in the x and y axis dimensions, but is partially limited in it’s ability to reach all z axis locations above the material table. Since there is a computer controlling our router, we need to get the part dimensions into the computer as a drawing file.

The three different ways for us to get these drawing files on board the router (in decreasing order of complexity and cost to the customer) are:

  1. Trace an example of the part and save the coordinates
  2. Create an original digital drawing from a hand sketch or paper blueprint and convert it to router machine language
  3. Use a customer’s existing computer drawing and convert it

Then the operator makes sure that the proper direction, rate and order of of cuts is programmed into the instructions for cutting the part. The cutting itself is done by spinning router bits. These bits are similar to drill bits but come in a much wider variety of sizes and shapes. They are selected based on the desired direction of cut, depth of cut, hardness of the plastic and a number of other factors.

After the part is programmed into the router’s computer, the plastic is placed on the perforated machine table and clamped down manually, or held in place by a vacuum created by the attached pump. This vacuum pressure is sometimes maximized along strips or ridges under the part by use of rubber strips or a jig (or both).

Once the operator instructs the CNC router to begin cutting the part, the table and the arm holding the cutting tool move independently to cut the part as quickly and precisely as is safely possible.

Once the part is programmed into the router’s computer, the plastic is placed on the perforated machine table and clamped down manually, or held in place by a vacuum created by the attached pump. Here is a video showing how this coordinated movement looks when a piece of ABS plastic is cut on a CNC router:

At Colorado Plastic Products, we rout plastic of many types for a wide variety of industries.  If you would like to learn more about our CNC overhead router capabilities, including lead times and pricing, please give us a call, or e-mail or fax us your drawing.