I have a cheap generic CNC mill that I got from China. It is one of my favourite tools, I use it to fabricate small parts out of plywood and acrylic and for routing circuit boards. I’m getting to the stage where I sometimes need to switch tools in the middle of a job. Usually when I’m making a circuit board (different tools are used for etching out the electron footpaths, vs drilling holes for other parts).

I busted a whole heap of tools figuring out how to correctly change them. Do things in slightly the wrong order or mess up your coordinate system and you will crash the tool into the workpiece and break your tool. This checklist is for changing tools with chillipeppr.


When the tool change dialog opens, press ‘close’:

Screenshot of chillipeppr's tool change pause dialog


Using the tool change functions on the left, switch the motors to full power. This helps hold your mill in place so that you don’t accidentally bump things out of alignment:

Screenshot of chillipeppr's tool change functions


Remove the current tool, and insert the new one. But don’t tighten the new tool in place, first gently step down on the z-axis till the tool is resting on the workpiece and firmly seated in the chuck. Now tighten the tool in place:

Photo's of removing tool from CNC chuck, gently moving down on Z-axis and tightening the new tool in place.


The tool should be at home on the z-axis, now we zero-out the z-axis to set the new tool level in Chillipeppr:

Screenshot of zero-out only the Z-axis in chillipeppr.


Step the z-axis up 10mm and press start spindle (for some reason some grbl files don’t always restart the spindle after a tool change - especially drill hole paths for circuit boards I have designed in Eagle):

Screenshot of starting the spindle in chillipeppr's tool change functions.


Your mill is now ready to roll, press the pause button to unpause the machine and continue the job:

Screenshot of chillipeppr's pause button to resume milling.