AC Relay for Air Assist/ Exhaust Setup

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The LaserBoard can automatically control your air assist, turning it on when a job starts, and off when a job finishes, and can also be set per layer for a job. This allows fine grain control of when your air assist is running and when it is not running. (Often, but not always, it makes sense to have air assist running for the whole job, but there are specific materials and settings where air assist is not desired, so this fine grain control can be very useful.)

The LaserBoard can also automatically control your exhaust system, but it is best to keep the control of exhaust separate from the control of air assist, since running exhaust is almost always desired. Therefore controlling the laser exhaust via the air assist control is not an ideal situation.

Below we’ll explain how to configure and wire the air assist to our AC Relay System, how to configure and wire the exhaust to our AC Relay System, and how to configure and wire the air assist and exhaust both together and separately.

Air Assist Only

Controlling air assist with the LaserBoard is simple. It’s already set up in the LaserBoard config file and LightBurn already issues the corresponding M106 and M017 commands to turn it on when a job starts and off when a job finishes. There’s a dedicated air assist connector on the LaserBoard, so you just connect the wire between the LaserBoard and the AC Relay System and it all works.

  • Pull out the green terminal block from the relay module.
  • Unscrew the terminals to open them.
  • Take the provided red and black signal wire.
  • Using the end with the bare wires, insert the wires, carefully noting the position of red to + and black to -.  It is a good idea to first strip the wires back a little bit so that there is enough exposed metal for good contact.
  • Screw the terminals back down over the wires, and insert the terminal block back into the relay module.
  • Insert the connector end of the signal wire onto the 2 pin male header labeled 5v Air Signal and again noting the correct orientation of red to + and black to -.
  • Finally, you’ll most likely want to connect your pump/ fan to one of the electrical outlets on the left side of the relay labeled “Normally OFF”.  This means that the device would be off, and would turn on when the signal from the LaserBoard turns on.
  • Make sure that the relay’s IEC power cord is plugged in to your wall outlet.  You can turn the relay on by flicking the red power switch to the RESET position.  You can turn your LaserBoard on, connect it to LightBurn, and send an M106 command through the console to see that your pump/ fan turns on.   Then send M107 to turn it off. Simple. (You do not need to read any further.)

Exhaust Fan Only

If you want to connect the exhaust to the LaserBoard so it will turn on when a job starts and off when a job finishes and do not have air assist connected, you can wire the exhaust to the air assist connector on the LaserBoard as shown above.  Then, Jump to section on Configuring Exhaust Fan Control below.

Exhaust Fan and Air Assist

If you already have an air assist that the LaserBoard is controlling you will need to connect the exhaust to an alternate output pin on the LaserBoard. We don’t have another one that is as neatly presented or protected, so you’ll want to be careful with this wiring as to not damage the board. We’re going to use pin 1.17 from the unused Ethernet Expansion Header along with a ground pin conveniently located directly above it.

In the image below pin 1.17 is marked with + and the ground pin is marked with -.

Note: You will need two of our AC Relay Systems so that the air assist and exhaust can be controlled separately.

Configuring Exhaust Fan Control

If LightBurn is not controlling your air assist, you can just enable Air Assist for all your layers and this will fill the role of turning on your exhaust fan at the start of the job and turning it off at the end of the job. Ultimately this is not recommended due to safety concerns, since you will need to always manually check each layer to ensure Air Assist is enabled so that the exhaust runs for the entire job. This is how it would work stock with no modifications, but again, is not the recommended method.

If LightBurn is already controlling your air assist, we’ll want to change the command that turns your pin on from the air assist commands of M106 and M107 to the other commands M3 and M5. LightBurn issues and M3 at the start of the job and M5 at the end of the job, so we will tell the board to turn these on.

If using the air assist output connector for the exhaust fan, change it in the existing fan block in the config file that is defined for pin 2.4.

Below is the stock config file showing M106 and M107:

## Switch module for fan control                            true                  M106             #                 M107             #                        2.4              #

You will need to change the 106 to M3 and the 107 to M5 as shown below:

## Switch module for fan control                            true                  M3               #                 M5               #                        2.4              #

If you are connecting the exhaust to the Ethernet expansion header instead of the air assist connector, use pin 1.17.

Below is the stock config file showing pin 2.4 specified:                        2.4              #

You will need to change the 2.4 to 1.17 as shown below:                        1.17             #

Configuring Air Assist Control and Exhaust Fan Control Separately

If you have air assist connected and controlled by the air assist connector, and you also have exhaust connected and controlled by the pin on the Ethernet expansion header, your config file should look like this:

## Switch module for fan control                            true                  M106             #                 M107             #                        2.4              #

## New config for exhaust
switch.exhaust.enable                            true
switch.exhaust.input_on_command                  M3               #
switch.exhaust.input_off_command                 M5               #
switch.exhaust.output_pin                        1.17              #

The two separate blocks will then be used to control air assist via LightBurn for any layer that has Air Assist enabled, and also control the exhaust, turning it on at the start of every job, and off at the end of every job.