Building a grblHAL Based CNC System - electronics.

Here are some schematic diagrams for the electronics of CNC machines based on grblHAL, from simple to complex.  There are 6 major categories of components though not all need to be present. Also you can mix and match features if you wish. For example, Ethernet can be added even to the Minimum System.

  • Controller (Breakout Board, Processor, grblHAL)

  • Stepper Drivers and Motors

  • Router or Spindle

  • Limit/Homing Switches

  • Control Inputs (EStop, Cycle Start, Feed Hold, Door, Probe)

  • Power Supplies

Minimum System

A minimal CNC system consists of the controller, steppers and drivers, power supply and a small trim router. It skips limit switches and control inputs. This includes an emergency stop button which is, strictly speaking, not absolutely necessary. However, we strongly recommend you have one as it can save your machine when you make a mistake. The router/spindle is manually controlled. Click on the picture to enlarge it.

wiring diagram minimal 2048.png

Add limits and inputs

The next step up adds limit switches and control inputs. The Cycle Start and Feed Hold buttons are extremely useful.  Limit switches prevent you from colliding with the sides of your machine and potentially damaging it. A probe helps to set the height of your cutter and find the edges of a workpiece. Click on the picture to enlarge it.

wiring diagram limit and contro 2048.png

Add Ethernet and Relays

Here we add relays to turn the router and dust extractor (aka shop vac) on/off automatically. This adds a lot of convenience.  It also shows using ethernet to connect to the PC. Ethernet is much more reliable than USB.

wiring diagram spindle control and ether

Add a Spindle and dust extractor switch

The final step adds a Spindle and Variable Frequency Drive (VFD). This has advantages over using a router - the speed can be controlled from GCode, it is quieter and can be much more powerful. Also shown is a switch to independently control the dust extractor - very useful for cleanup after a job is done.

wiring diagram full 2048.png