Install AirAssist Relay in k40 with C3D mini

Machine: K40
Board: C3D mini (purchased Sept 2018)
Firmware: Smoothie (Stock as it was shipped)

I have a mini board and would like to connect it to a relay controlled outlet for air assist and exhaust. The relay board I have needs +5 and ground to control the relay.

What pins on the Mini should I connect it to and what changes in LightBurn settings do I need to make.

thanks for your help
Brian

Hi Brian, welcome to the forum.

Without knowing the specs of the relay module you are using we can’t get too specific, but for the Mini you could use the pin labeled P2.6 which is MOSFET3. (See image below.)

You will need to edit the config file. By default it looks like this:

## Switch module for fan control
switch.fan.enable                            false
switch.fan.input_on_command                  M106             #
switch.fan.input_off_command                 M107             #
switch.fan.output_pin                        2.6              #
switch.fan.output_type                       pwm              # pwm output settable with S parameter in the input_on_comand
#switch.fan.max_pwm                           255              # set max pwm for the pin default is 255

Change switch.fan.enable from false to true and if you use pin P2.6 you should be all set.

(If for some reason you choose MOSFET4 you would need to use pin P2.4 instead.)

It should look like the below snippet after your edits:

## Switch module for fan control
switch.fan.enable                            true
switch.fan.input_on_command                  M106             #
switch.fan.input_off_command                 M107             #
switch.fan.output_pin                        2.6              #
switch.fan.output_type                       pwm              # pwm output settable with S parameter in the input_on_comand
#switch.fan.max_pwm                           255              # set max pwm for the pin default is 255

The M106 and M107 commands you see will then take care of turning on and off the MOSFET via LightBurn.

You can check out this Knowledge Base articles for a bit more on the basics of air assist connections.

(It’s focused on using the LaserBoard not the Mini but still provides useful background information.)

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thank you for the quick and detailed answer.

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