Has anyone used a duet for a laser cutter?



  • Just curious if anyone out there has tried to use the duet for a laser cutter/engraver.

    It seems like it should be more then capable hardware wise. Just wasn't sure if anyone has been able to get the electronics set up to raster.

    I have been considering using an xcarve frame for motion harvesting the mirror laser tube and laser power out of a cheap Chinese cutter. Just haven't decided on the control board.

    (Yes I know I will need to enclose the frame and all the other tidbits for a laser to be safe)


  • administrators

    Duets have certainly been used for laser engravers, but I've not heard of one being used for a laser cutter yet. I am interested in adding better firmware support for laser cutters, so if you decide to use a Duet WiFi or the forthcoming Duet Ethernet, let me know what your requirements are. Previously, the M571 command has been used to turn the laser on/off in laser engravers.



  • @dc42:

    Duets have certainly been used for laser engravers, but I've not heard of one being used for a laser cutter yet. I am interested in adding better firmware support for laser cutters, so if you decide to use a Duet WiFi or the forthcoming Duet Ethernet, let me know what your requirements are. Previously, the M571 command has been used to turn the laser on/off in laser engravers.

    So people have used it for raster and or vector operations? Do you have any links? I am 100% confident that its within the capabilites of the board but I am not sure what software to use with the duet to generate the nessessary code.

    What is the differnce beween the wifi and the eithernet? Is it just type of connection or is there more?


  • administrators

    I was wrong, the Duet has been used in a laser cutter. See http://forums.reprap.org/read.php?133,521301.



  • @dc42:

    I was wrong, the Duet has been used in a laser cutter. See http://forums.reprap.org/read.php?133,521301.

    I was thinking the same thing for a cut, but if you want to engrave an image its a whole different process. I found this interesting instructable but I am not sure how it would be adapted to the Duet as it doesn't appear to be based in gcode. So I would have to write a new program.

    http://www.instructables.com/id/Arduino-Laser-Engraver/?ALLSTEPS

    I have been thinking somewhat along these lines, you could send gcode to move a pixel and with a PWM value for the laser. To me it seems like it would be too many instructions per second but in reality I have no idea how many the duet can handle.

    If we assume like in the instructable that a pixel is 0.1mm and that that absolute minumum speed I would want the laser to move is 300mm/s it would translate to 3000 instructions per second. You will be moving only one axis and setting a PWM value.

    The higher end lasers can move up to 1000mm/s but I think I would be pretty happy at half that.

    EDIT:
    After some poking around the Duet is clearly fast enough stepping wise, but I have no clue how that translates to interpreting rapid gcode
    Off of reprap.org
    Axis Setup: 1.8°-stepper, 20-teeth-GT2-pulley, 1/16 microstepping
    steps per mm: 80
    Duet Wifi speed: 3000 mm/s



  • I plan on testing to see how many instructions I can execute per second on my 3d printer, but does anyone have any idea what the limits might be?


  • administrators

    I just "printed" a 15600 line file in simulation mode using M37 and it took between 7 and 8 seconds. So it's about 2000 lines of gcode per second. It will be a little slower in real life when the step interrupt is firing and individual step calculations are done.

    There is probably scope to increase the throughput if it becomes critical,. I remember doing some experiments to see if the move system was ever being starved of incoming data during a high-speed print, and it wasn't - so I haven't spent any time optimising that area.

    If what you are trying to do is laser engraving using a raster approach, I think it might be a good idea to use a more efficient command representation than one line of gcode per 0.1mm. For example, you could have a virtual tool with 10 extruders, then you could send a line of gcode that does 1mm of movement and has 10 extrusion values, with each one used to define the intensity for 0.1mm of movement. Assuming you are able to generate the data in that format with whatever you are using to generate gcode.



  • @dc42:

    I just "printed" a 15600 line file in simulation mode using M37 and it took between 7 and 8 seconds. So it's about 2000 lines of gcode per second. It will be a little slower in real life when the step interrupt is firing and individual step calculations are done.

    There is probably scope to increase the throughput if it becomes critical,. I remember doing some experiments to see if the move system was ever being starved of incoming data during a high-speed print, and it wasn't - so I haven't spent any time optimizing that area.

    If what you are trying to do is laser engraving using a raster approach, I think it might be a good idea to use a more efficient command representation than one line of gcode per 0.1mm. For example, you could have a virtual tool with 10 extruders, then you could send a line of gcode that does 1mm of movement and has 10 extrusion values, with each one used to define the intensity for 0.1mm of movement. Assuming you are able to generate the data in that format with whatever you are using to generate gcode.

    Ah, I like your suggestion for the raster approach! I was hoping there would be a way to make it more efficient I just had no idea how, as I am just starting to really learn the duet.

    Right now I plan to write the program to generate the gcode off a gray scale image. I have played around with images in the past and integrating that into openscad so I already have half the process solved, so I should be able to generate the gcode in what ever format that will work the the best.

    My big laser etching order is done so I could integrate a duet now while it down for a bit, but just want to prove that it's possible before I by a second duet wifi. Do you have a link with some info to get me started, if now I will scour the wiki tonight. I am thinking about using an led to simulate a laser and watch it brightness, I don't think I want to the the bigbox a 300mm/s but maybe I can increase the instructions per mm



  • I unfortunately haven't had a chance to run my test, just curious if you had thought about it anymore since Feb. I am using a board in my laser right now that is rather limited in around 16mm/s when trying to raster, way to slow for the types of project I usually do.


  • administrators

    Version 1.20beta1 supports the M3 command, which is the same command that I understand Repetier firmware uses to control lasers.



  • Hi im thinking to build a CNC CO2 laser, and because i already have a duet it would be nice if i can use a duet for this machine to.

    Laser cutting should not be a problem, but how to engraving in raster mode with the duet.

    merlin uses G7 to execute a raster line ( base64 encoded line ) and i think there is a inkscape plugin to generate the g-code for merlin.


 

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