gnexlab controller card ver 2.1

gnexlab controller card is a temperature monitoring and PID temperature controller for FDM 3D printers. If you have a desktop CNC machine you can easily convert your CNC to a 3D printer with this controller card. Please also check what else do you need section for the other required parts.


  • Standalone No PC Connection Required
  • Based on the Arduino Diecimila (Atmega 328)
  • Small (84*48 pixel) Graphic LCD (Nokia 5110)
  • User Friendly With Menus
  • 3 button usage (UP/OK/DN)
  • 2 High Power MOSFET Outputs (5A at 12V)
  • 2 Relay Outputs
  • 2 Thermistor Input
  • 1 Thermocouple input (Max6675)
  • Can Be Powered With ATX PC Power Supply
  • 2 PID Computation Via On-board Micro-controller

How To Use

  • Selecting Sensors

This board has two separate functions. One is controlling Extruder temperature and the other is controlling the Heated Bed temperature. This is accomplished with on-board PID computations. In order to start using your gnexlab controller card you have to select the sensors to measure the temperature of the Extruder and the Heated Bed. We have tree options for the sensor inputs, one for a thermocouple and two for thermistors. We just need two of them. One for the extruder and one for the Heated Bed and I suggest you use a thermocouple sensor for the extruder because accurate temperature measurement here is critical for high quality 3D printing. Please take a look at this information taken from the makerbot website.
Thermistors are nice for general, low-quality temperature measurement. Once you get above 150C, its time to step it up. Thermocouples are a really solid way to measure high temperatures. They are accurate, reliable, and high tolerance. They also have the side benefit of being easy to mount. Simply bolt the thermocouple to the side of your thermal core and you’re ready to go.

You can select to use one thermistor for the measurement of the Heated Bed temperature. For a budget friendly version you can also use one of the thermistor for the Extruder.

  • Selecting Outputs

In order to control your heaters you can use either power mosfets or relays and there are two of each type of circuit provided on the board. Again you will use one for powering the Extruder and one for the Heated Bed. I have designed this card with four outputs, mainly for future developments but also to provide spares just in case a circuit is accidentally damaged as the result of a wrong connection. The outputs are driven with PID computution. We have to thank the new arduino PID library. For the relays we are using “time proportioning control” because this function of the library is ideal for controlling relay outputs. I will not go into the full details here but if you want to know more on how this all works then please take a look at the Source code. 

  • Setting the Temperatures

We have to define a Set Temperature Value for the Extruder and the Heated Bed. Please try first with 250 Degree Celsius for the Extruder and 120 Degree Celsius for the Heated Bed. The controllers main job is to set the temperatures at this values with PID. The Kp,KI and Kd parameters are hard coded to the source code. You can try different numbers if you are an expert.

  • Start

The above mentioned settings are stored in the micro-controller EEPROM. So you will make the settings once. (If you are happy with them. If you are not you can change them anytime. ) You will just select the Start from the menu in regular daily use. This will activate the temperature monitoring software uploaded in the micro-controller.


The Design and Source Files

Please check the github repository for all the design files related with technology.

7 thoughts on “gec2.1”

  1. Couldn’t get your film clips to load (crash in Flash). Looks like a great solution for large bed printing. Is that a touch screen? I’m thinking a quick disconnect for router and some very nice things could happen. Laser made PC boards, laser or plasma cutting, 3D printing. All for a few hundred dollars. Any examples.

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