CNC Job Completion Alarm

I’m currently building a CNC mill and laser cutter all in one machine based on the Shapeoko 2 running GRBL. It spans 1M by 1M which is pretty big and to keep the noise down in the house it lives in my workspace in the attic of the house. This is great because it’s out of the way but more secure than being in a shed!

The problem I run into with this setup is that it’s good being out of the way but I never know when the current job is finished. For this I had the idea of having an audible alarm that would sound as soon as the job is finished. I did my research and this is what I’ve come up with as my solution.

Here’s my CNC shield I am using on my Arduino:
Arduino-CNC-shield-V3-630x552

On here you can see the CoolEn pins. These are the coolant enable pins that are linked to GRBL. For my CNC I have no use for this pin as I’m not running a coolant system (my mill will mostly be cutting plywood, MDF and maybe acrylic so theres no need to flood cool anything!). I have these attached to an opto isolated relay circuit that is in turn connected to a really annoying 5v piezo buzzer. This is then triggered at the of the GCode file by my little bit of code I add manually to the end just before the M30 command:

(Alarm Buzzer 5 Seconds)
M08 ; Coolant Enable Command
G04 P5 ; Dwell for 5 seconds
M09 ; Coolant Disable Command

This is all I do! When the job finished it gives a shrieking buzz you can hear throughout the house and tells me that the job is finished.

I have already been looking at ways of improving this – I’m looking at a doorbell like system based on Arduino with transmitter and receiver modules and flashing LED alerts that I can have remotely with me in the house. I will post further updates on this in the future – keep an eye out!

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