The 3020 CNC router is a popular Chinese machine for a good reason. For around 500EUR, you can have a simple CNC with a rigid all-aluminum frame, three decent stepper motors, and pretty good resolution. However, a major disadvantage of this CNC is the out-of-date electronic parts.
The motor controller is using a parallel port which is not available in any new computer(PC). For that reason, it is recommended to upgrade the motor controller to support USB. There are several options ($) depending mainly on your budget, but I think it is superfluous to spend more than 30-40EUR for this upgrade.
First of all, let’s take a closer look at the original motor controller of the CNC as well as the adruino-based motor controller.
As you can see there are 3 (Molex 4-pin) cables for each stepper motor, 1 (Moles 2-pin) cable for the power supply and 1 (Molex 2-pin) cable for the e-stop button (emergency button). These cables should be connected to the corresponding connectors of the new motor controller. (Beware that you will need some extra parts to convert the Molex pins to 2.5 arduino-like pins). I suggest to leave the original cables untouched and use some converters but this depends solely on you.(well i haven’t)
The result should be something like this.
Finally you have to flash the arduino with GRBL and use an appropriate program to send G-Code such as Candle.(Checkout the GRBL wiki/documentation for more info.. the process is straight-forward)