Duet 2 Wifi performance for laser raster printing



  • Is there any benchmark that shows how many gcode/second can Duet 2 process?

    I have a Duet in my 3D printer and love it, used it with a blue laser and did well. Now I'm planning to use it with K40 CO2 laser cutter, but it looks like everyone is using Cohesion3D https://forum.cohesion3d.com/t/improved-raster-speed-firmware-update-for-cohesion3d-boards/850 .
    The CO2 laser raster printing can be done much faster than blue laser which makes me worry that Duet won't be able to support it.



  • hmm
    looking at the processor.

    32 bit LPC1769 Microcontroller running at 120Mhz,
    vs
    Powerful 32 Bit Processor: Atmel SAM4E8E: 120MHz ARM Cortex-M4

    upcomming duet3
    Powerful 32 Bit Processor (ARM Cortex M7 @300Mhz)

    the performance is explained here
    https://reprap.org/wiki/Step_rates#Achievable_step_rates

    Smoothie on Smoothieboard with 120MHz ARM Cortex-M3 (no FPU): 120 kHz (configurable, 120k is default, rates up to 200 are

    RepRapFirmware on Duet WiFi (120MHz ARM Cortex-M4, firmware 1.17d) using up to octal stepping at high speeds: 360kHz with one motor moving, and 180KHz simultaneously on 3 motors

    However do take into account that the board is specialised for laser cutting. so i would expect a lot more optimization in the firmware of the cohesion compared to the duet for laser operation. I have just read a few post about people using the duet laser mode (https://duet3d.dozuki.com/Wiki/Gcode#Section_M452_Select_Laser_Printer_Mode)



  • I did some testing and while the hardware and implementation would point that Duet should be faster the tests show otherwise.
    My results:
    Firmware 2.0.2
    300 DPI raster @ 200mm/s UI was showing max top speed 30mm/s out off requested 200mm/s
    100 DPI raster @ 200mm/s UI was showing max top speed 67mm/s movement was visibly faster
    Firmware 2.0.4
    100 DPI raster @ 200mm/s UI was showing max top speed 81mm/s

    The last job had 16k G1 moves and completed in 60 seconds which means Duet can process about 267 gCodes/second which is 10 times less than Cohesion3D.

    Can anyone familiar with the firmware ( @dc42 ) confirm that my results make sense or I should be looking into configuration/gCode problems?

    My setup is Ender-3 theoretically able to deliver movements of 220mm/s and configured like that (M203 X12000 Y12000 Z900 E3000 ).
    The test was executed using web UI to upload and start the job.
    My files:
    config.g
    duet.gcode
    LASER MODE macro.g



  • M566 X600 Y600 Z24 E300                   ; Set maximum instantaneous speed changes (mm/min) MARLIN
    ;M203 X9000 Y9000 Z900 E3000               ; Set maximum speeds (mm/min) MARLIN
    M203 X12000 Y12000 Z900 E3000             ; Set maximum speeds (mm/min) MARLIN
    M201 X500 Y500 Z100 E5000                 ; Set accelerations (mm/s^2)
    

    With your low acceleration and jerk values I'm not sure you'd be able to hit 200mm/s on the small bed of the ender 3 anyway.

    With 500mm/s^2 it would take nearly 50mm to reach 200mm/s and with a jerk value of 600mm/min you'd have to slow down to 10mm/s at every hard segment.

    Try increasing your acceleration to 2000 and your jerk to 1200 and see if that helps your top speed.



  • Thanks @Phaedrux it was my mistake I didn't think about bumping acceleration and jerk.

    It did help with the performance I can hit 136mm/s and the job is completed in 36 seconds which increased the throughput to 444 gcode/sec, but there was a side effect.
    The gCode instructs the machine to move a laser along x-axis for 120mm and then proceed with next line. The movement is a very uneven entire machine is jerking but not on direction change but during the long movement. I tried both 2000 and 1200 jerk as well as some very high values like 20000 and 12000 with the same result.

    I think it is because there is some delay between executing the commands and the x-axis motor constantly decelerates and accelerates instead of doing long streaks.
    I'll play with the config and remove the laser/extruder to see if it is a mechanical limitation or a firmware problem.

    Video showing jerk during long movements: https://youtu.be/ePAcdSWWiTc



  • I played a bit with the speed and it looks like the limit is 140mm/s for 100 dpi at this speed the movements are smooth anything higher makes "Top speed" value to fluctuate and printer jerk during the long moves.

    The limit of Duet is:
    3.94 px / mm x 140mm/s = 551.6 gcode/s

    It is about 5 times slower than Cohesion3D and 2 times slower than default Smoothieware.
    I'll create a new topic in wishlist category to find out if there is any desire or even if it is possible to improve the firmware to support higher speeds.


  • administrators

    We looked into high speed laser rastering earlier this year and came up with a proposed GCode extension to better support it. See https://docs.google.com/document/d/1SMWFJUXfRSxe-p-veWEP-NU3A9ESKU_TVGB1Y1ADAV8/edit?usp=sharing.



  • @spw said in Duet 2 Wifi performance for laser raster printing:

    Video showing jerk during long movements: https://youtu.be/ePAcdSWWiTc

    I think that may have more to do with the motors of the Ender 3 than the Duet.

    The belts also look loose?


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