Plug & play FluidNC K40 shield for Lightburn (V8.XX)

Attention ! This post is only valid for FluidNC K40 shields with a version >= 8.xx

This shield is optimized for K40 laser cutters but it works with all types of machines including diode lasers

You can buy this plug & play shield here : Link

First step is to install Lightburn (Link)
It is very important to set it exactly as I ask in the post above.

Once Lightburn is installed, please refer to the correct section of the post depending on your machine equipment. This post seems long, but it takes into account all the possible configurations of the K40s. You will only have one case to perform on your machine.

Important note : if your machine is very old, you could have an orange motherboard with a 6 pins power connector. My shield will be compatible with this kind of machine, but you’ll have to rewire a little bit this connector as +24V and GND are swapped compared to all new motherboards (green & purple ones). Please contact me if you are equipped with this orange board.

Case 1: Machine with digital panel, equipped with a ribbon cable – Click here

Case 2: Machine with digital panel and not equipped with a ribbon cable – Click here

Case 3: Machine without digital panel, equipped with a ribbon cable – Click here

Case 4: Machine without digital panel and not equipped with a ribbon cable – Click here

Case 1 (digital panel – ribbon cable)

In this configuration, the installation of the FluidNC K40 shield is plug & play.
No need to modify any connectors.

Old boards :

New FluidNC K40 Shield :

Simply disconnect the 4 cables from the old cards and reconnect them to the new card, keeping the color code. Your machine manufacturer may have used hot glue to secure the connectors. Just carefully remove enough glue to get the connector out of the old boards (don’t try to remove all the glue).

For the orange connector (the one that was connected to the digital board under the hood), you will have to take the wires associated with this connector out of the cable sheath. The goal is to have enough slack to be able to connect to the new shield.

For the gray connector (the one that connects to the Y axis on the new card), you must put the red wire of the cable towards the bottom of this photo (in other words the red cable must be on the side of the connector Z axis)

For the yellow connector (ribbon one), you must lift the white connector on your FluidNC K40 shield to open it, then insert the metallic contact ribbon cable towards the outside of the board (therefore upwards in the photo above), then close the connector

Now connect to connect the USB cable (micro USB format) to the processor of the new board (electronic component in the middle of the board)

Case 2 (digital panel – no ribbon cable)

In this configuration, the installation of the FluidNC K40 shield is plug & play.
No need to modify any connectors.

Old boards

New FluidNC K40 shield :

Simply disconnect the 5 cables from the old cards and reconnect them to the new card, keeping the color code. Your machine manufacturer may have used hot glue to secure the connectors. Just carefully remove enough glue to get the connector out of the old boards (don’t try to remove all the glue).

For the orange connector (the one that was connected to the digital board under the hood), you will have to take the wires associated with this connector out of the cable sheath. The goal is to have enough slack to be able to connect to the new shield.

For the blue and gray connectors (those that plug into the X and Y axes on the new board), you have to put the red wire of the cables towards the bottom of this photo (in other words the red cable of each connector must be on the side of the Z axis connector)

Now connect to connect the USB cable (micro USB format) to the processor of the new board (electronic component in the middle of the board)

Case 3 (no digital panel – ribbon cable)

In this configuration, it will be necessary to wire a 5-way Dupont connector (Amazon link).
No soldering required to install your FluidNC K40 shield.

Old board :

New FluidNC K40 Shield :

Simply disconnect the 3 cables from the old board and reconnect them to the new board, keeping the color code. Your machine manufacturer may have used hot glue to secure the connectors. Just carefully remove enough glue to get the connector out of the old boards (don’t try to remove all the glue).

For the gray connector (the one that connects to the Y axis on the new card), you must put the red wire of the cable towards the bottom of this photo (in other words the red cable must be on the side of the connector Z axis)

For the yellow connector (ribbon one), you must lift the white connector on your FluidNC K40 shield to open it, then insert the metallic contact ribbon cable towards the outside of the board (therefore upwards in the photo above), then close the connector

It is now necessary to wire the brown connector on the left of the photo.
See section below : Wire the Laser Management connector

Now connect to connect the USB cable (micro format) to the processor of the new card (electronic component in the middle of the card)

Case 4 (no digital panel – no ribbon cable)

In this configuration, it will be necessary to wire a 5-way Dupont connector (Amazon link).
No soldering required to install your FluidNC K40 shield.

Old board :

New FluidNC K40 Shield :

Simply disconnect the 4 cables from the old board and reconnect them to the new board, keeping the color code. Your machine manufacturer may have used hot glue to secure the connectors. Just carefully remove enough glue to get the connector out of the old boards (don’t try to remove all the glue).

For the blue and gray connectors (those that plug into the X and Y axes on the new board), you have to put the red wire of the cables towards the bottom of this photo (in other words the red cable of each connector must be on the side of the Z axis connector)

It is now necessary to wire the brown connector on the left of the photo.
See section below : Wire the Laser Management connector

Now connect to connect the USB cable (micro format) to the processor of the new card (electronic component in the middle of the card)

Wire the Laser Management Connector

You must skip this section if your machine was equipped with a digital panel.
In this case, go directly to the connecting to a computer section of your Shield FluidNC K40.

This step is therefore only necessary if your machine was equipped with a potentiometer for adjusting the power.

There are three possible power supplies for a K40:

Type 1 (Green connectors)

If you have this power supply (and no digital panel), disconnect the wires connected to the L (twice) and IN slots

You must now connect the power supply and your FluidNC K40 shield as follows :
L of the central connector of the power supply on ENA (L) of the new board
IN of the central connector of the power supply on PWM (IN) of the new board
G from the middle of the central connector of the power supply to GND of the new board

Type 2 (White connectors)

If you have this power supply (and no digital panel),

Leave the K-/K+ connector connected. There is only one wire connected to this connector. Follow him to the hood of your machine. Cut it as close as possible to the hood of the machine. We will call this wire L

Leave the G/IN/5V connector plugged in.

• Follow the IN wire that goes to the hood potentiometer. Cut the wire the closest possible to the potentiometer. We will call this wire IN
• Follow wire G that goes to the hood of the machine. Cut the wire the closest as posisble to the hood. We will call this wire G

You must now connect the power supply and your FluidNC K40 shield as follows :
Wire L of the K-/K+ connector of the power supply on ENA (L) of the new board
Wire IN from the G/IN/5V connector of the power supply on PWM (IN) of the new board
Wire G of the G/IN/5V connector of the power supply on GND of the new board
The 5V wire of the G/IN/5V connector does not matter. You can delete it if you wish. If you keep it, be careful to insulate it well.

Type 3 (black case – in general for laser > 50W)

If you have this power supply, my FluidNC K40 shield can be installed.
However, contact me so that I can guide you through the installation!

Connecting your FluidNC K40 shield to a computer

Connect the USB cable from your PC to your ESP32

Then, in Lightburn, click on the “Console” tab in the right column. You should see something like :

Now right click on the “Devices” button in the right column.
This will restart the USB/Serial connection between Lightburn and the ESP32.
You should see indications similar to the one below on the console:

If so, your computer and laser cutter connected as intended.

At this stage, you probably have errors on the Lightburn console
(Alarm 14, Alarm 1 or/and error 8). It’s normal.
You can proceed to the next steps.

Otherwise, check carefully:

• That the USB connection speed is correct (Edit/Device Settings): it should be on 115200 bauds
• That the DTR control is activated (Edit/Device Settings)
• That your USB cable is a data cable and not only and charging cable and that its length is below 80cm

It is also possible that the USB driver is not compatible with your ESP32.
You should then download and install the right version by going here :
https://www.silabs.com/developers/usb-to-uart-bridge-vcp-drivers
Direct links :
For windows : CP210x Windows Drivers with Serial Enumerator
For MacOS : CP210x VCP Mac OSX Driver

If that still doesn’t work, it is possible that you have multiple devices on your PC that use the COM ports.
Go to your computer’s device manager (Windows key + R and enter devmgmt.msc)
Look for COM and LPT devices

Note the number of the COM port associated with the Silicon Labs CP210x driver installed just before and check that Lightburn is using the same COM port:

Réglage de l’axe Z :

Very important: if you have purchased your FluidNC K40 shield with 3 or more drivers but you do not yet have a motorized bed / Z axis, you must absolutely deactivate the Z axis homing.
Otherwise your machine will not work.

To disable the Z axis, enter the following commands, one at a time, waiting for an OK response between each command:

$axes/z/homing/cycle=0
$cd=config.yaml
$reset

To re-enable Z axis homing, enter the following commands, one at a time, waiting for an OK response between each command:

$axes/z/homing/cycle=2
$cd=config.yaml
$reset

If you have a Z axis / motorized bed, go to this article section “Z axis adjustment” to adjust it (link)

First start of your FluidNC K40 shield :

If you have followed my instructions to the letter, at this point your machine is not yet powered on -> check that the machine is not powered

Position the laser head in the center of the work area by hand

Turn on the machine

Be prepared to turn off the power to the machine if the head does not move in the correct direction in the next step.

Click the HOME button in lightburn

Normally, the head should go to the upper left corner of the machine, then come back 5mm on both axes towards the center, then go back towards the corner, then come back one last time 5mm on both axes towards the center (so 4 steps in all)

If there is any error in the console / the slightest warning, or you do not see an OK in the lightburn console, the HOME did not work.
It is essential to solve the problem before going further
You can get help from this article (Link) – If despite the explanations in this post you can’t solve the problem, contact me.

Once HOME is successful, you can use your machine with Lightburn!

Bravo !!

At this point you have a K40 with brand new electronics able to work with Lightburn, a motorized bed and lots of new features!

Check that you have the latest firmware and configuration file by reading this article: link

Remember that after powering up your machine, the shield cannot know where the head is.
It is therefore essential to launch a HOME via Lightburn each time you turn on your machine!

You still have to learn how to use Lightburn in detail: link to the manual

Link to the STL to print the shield support : Link

Connecting an air assist :

If you want to connect an air assist, you can follow the schematics below.
Connections on the shield are on the green connector (no polarity)
Link to relay (no affiliation)

Please make sure that you have configured Lightburn as per my instructions (M7 instead of M8 to drive the air assist relay in Edit / Device settings)

Z & A axis wiring :

If your stepper motors are making strange noises and shaking, it’s either due to too much load (too much resistance for example) or more likely a different pinout from the stepper motors you purchased. Indeed, there is no standard, and two NEMA17 motors for example, can have different wiring.

For reference, my board is wired as follows.
You must connect the two outputs A (A1 and A2) of my card to the inputs A (A and A_stroke) of the motor. Ditto for outputs B (B1 and B2).

More information can be found in this post : Lien