Laser Interface/Driver PCB

This a the new Laser Interface PCB.  It adds a lot of new features including the stepper motor drivers.   This board is designed to reduce the wiring requirement of a home build laser cutter/engraver.  This should significantly reduce the cost of a laser cutter.  If you use this with EMC2 (free) you should be controlling your laser for less than $100. There is a video at the end of the post.

Controller Connector

This is a standard 25 pin ‘D’ connector.  The pinout is compatible with PC control (Mach3, EMC2) or the FSE Retina Engrave controller.

Stepper motor Drivers

The PCB provides three slots for Pololu stepper motors drivers.  It can use the A4983 or the A4988 stepper drivers.  The PCB provides the logic power so you use the cheaper versions of the boards.   These drivers can provide up to 2amps of power at resolutions up to 1/16 step.  The microstep mode is easily adjustable through rotary DIP switches.  These are placed along the edge with the control connector so they can be made accessible through the enclosure wall.   If you ever blow a driver, you can simply replace the broken one.  There is a built in fan to cool the drivers that cools them to within a few degrees of the ambient temperature.

Safety Loop

The board creates a safety loop of switches to protect the user and laser tube.  The loop runs through the emergency stop button, the cover switch and the water flow switch.  If any of these items are are not in the run position or if there is a break in the loop, the laser tube cannot be enabled.

Laser Power Control

The board allows two different laser power control modes.  The default mode is via a remotely located manual potentiometer.  This is usually mounted on the front panel.  You can also use a switch to change to PWM mode.   This allows an external controller to provide a digital PWM power level control.  This switch would be located on the front panel.  The PWM signal can be configured to use pin 14 or pin 15 on the 25 pin connector.

Dual Relay Drivers

The board has two high current MOSFETs that can be used to drive external relays.  these are controlled via pins 1 and 8 on the 25 pin control connector.  These are typically used to control assist air and exhaust blowers.  They can easily be configured through Mach3 or EMC and G-Code as if they were mist and flood coolant devices.

Laser Power Supply Connector

There is a direct 1:1 connection to standard laser power supplies.  The board takes car of connecting all the grounds and safety interlocks.

Water Switch

There is a three pin terminal block to connect to the water switch.  The switch can be a simple mechanical switch, plus there is a 5V power source to use if you want to power a more complex water monitor.

Enclosure Connections

There is a connector dedicated to the enclosure connections for the limit switches and cover interlock.  The board provides the pull up resistors for these items so they can be wired in a mode where a break in the wiring would trigger signal an open circuit.  The pull up value can be either 5V or 3.3V.

User Guide

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23 Responses to “Laser Interface/Driver PCB”

  1. Ed

    Wow. Congrats Bart – this really rocks! Look forward to seeing them in the store…

  2. Dirk

    When will this be available? Will it be sold as a complete board or do we have to solder it all together?

  3. bdring

    It will be available after a little more testing. It will be kit or assembled. You need to buy the Pololu drivers separately. Watch the forum to see when it is ready.

  4. Dirk

    May I suggest adding a 4th axis for a rotary engraver or at least providing isolated pinouts for a 4th axis so we can add a driver on our own?

  5. bobf

    I also need a rotary axis. Here is the use case: multiple plat boards need be linked together by round or rectangular beams, and the beam and boards don’t intersect at 90 degree. To cut slots to accept the beam, the board need be rotated. In short, a 4th axis will be valuable if we need add further capability down the road.

  6. bdring

    4th Axis.

    Right now there are not enough outputs to support a 4th axis. There is one unused output and two are used for the relay drivers.

    My theory is that the Y axis essentially needs to be disabled to use the rotary, so I plan on swapping the cable. I will have a convenient connector accessible from the top to swap them.

    I could make a 4 axis version in the future with only one relay driver, but the next version will be 3 axis. I can’y afford in time or money to two at once.

  7. mdcatc

    What are the main differences between your PCB and the G540? I have a couple of G540 as backups for another table I have. And would like to keep them with as many common parts as possible. I know the G540 supports 4 axis and has a couple aux relay’s etc. But perhaps its not got enough to support all the modes of the laser.

  8. bdring

    The main difference are the special features for the laser, like the safety loop. If you have a G540, can hand wire the safety loop etc, and are OK with the fixed 10 microstep resolution, I would use it.

  9. kreangsak

    how many 1 pcs.

  10. bdring

    Price is $99 or $139 with drivers and heatsinks

  11. callcbm

    is this board complete for the 139.00 or do You have to purchase it as a kit form
    Thanks Randy

  12. bdring

    It is $99 for the built and tested “motherboard”. The Drivers are $14 each for the Pololu drivers with heatsinks.

  13. Laser Rebuild – Part 2 (control) « The Hell Ya Beller

    […] interesting but once again, the Buildlog guys seem to have anticipated my needs perfectly.  The laser interface driver uses pololu drivers which I'm familiar with from my Reprap RAMPS board.  The pololu stepper […]

  14. Dan

    I’m interested in building this too. But the link above is not good any longer, .
    Would there be another link to get this driver board ?


  15. bdring

    It is sold here, but currently out of stock. It will be back in stock in about 10 days.

  16. Snarkhunter

    Curious if this board is still available assembled complete with drivers and heatsinks. Thanks.

  17. bdring
  18. ISchuch

    It looks like a great project! No boards are available on the link. Will they become available again? Is it possible to get the assy?

  19. bdring

    Open source documentation is available here.


    There are NO more assemblies or raw boards for sale.

  20. gundog48


    Sorry to hear that there are on more boards for sale. Would you be able to upload the PCB file so I could make it/have it made myself?


  21. bdring
  22. arnette

    is the stepper motor driver of linistepper v2 ( is compatible with this laser interface driver ? please answer back thank you.

  23. alain

    hi there a newbie question

    with mach 3 what card is need ?
    corel ?

    if i already have a cnc router , is there a way to minimise the cost by making a kind of A and B option boxe for switching between the two machine.
    can i use my drive , multi use board , pmdx 126 card,the transformer.

    the only think would to buy the tube ,card for the tube .

    did i say something not ok ?

    give me feed back i’m trying to figuring out how it work for making my mind about that.

    please give me some think for working with.

    i’m french canadian and is no information about nothing around hear.