In my search for the best affordable CNC motherboard for my new to build Indymill CNC machine I finally chose the GT2560 from Geeetech as best compromise. At least for now, and maybe later I may change to an RRF3 board with a good remote CNC interface like the Mellow Fly-CDY-V2.
The board has a budget price and utilizes an atmega chip with great performance.
The board does not come with the CNC GRBL firmware installed, you can get the required arduino library HERE for the Arduino Mega with the add-on RAMPS 1.6 board and HERE for the GT2560 integrated board!
The nice thing about this board is that it can be flashed with the arduino IDE, and I like the board especially because I can plug in the NEMA23 closed loop stepper motor cables directly in the driver connectors of the GT2560 board. By doing so, I don’t need the lumpy seperate 6600 driver units and I never miss a step. These closed loop drivers get attached to the rear of the Nema23 stepper motors and use the 24 Volts from the wiring to the GT2560 driver socket. The max Amps is 4 Amps per unit and this is enough to have good CNC results. I also added the tiny LCD’s into the closed loop units, this makes it possible to perform local management like the initially required one-time calibration of each stepper without the need for a PC. And= the display also shows the status of the stepper motor (errors, missed/corrected steps etc).
The required Gcode can easily be made with Esticam. I first make my design in Openscad, export the design as .STL file in the highest resolution ($Fn at 128 or higher) and import the STL file in Esticam. Then I use Esticam to send the Gcode via a USB cable in the GBRL format to the GT2560 board. BUT- it is also possible to save the CNC file output from Esticam and put it on an SD card. The LCD unit that is attached to the GT2560 accepts SD cards (formatted as FAT 32) so you can work independantly of a PC.
Or- you can connect your Mega2560 to a Raspberry PI and use the Raspberry PI as webinterface , to control your CNC machine via wifi from your PC or phone/tablet.
Please read on about how I use this setup for my IndyMill CNC machine!