Laser power adjustment/speed



    1. DC42, check to make sure your server email is working, it's Clearlynotstefan, but reset your password emails haven't come through for the 2 weeks I've been trying

    Anyway! I'm building a big laser engraver/cutter and looking at boards. Of I would prefer to buy another duet wifi ❤ turns out people recommend smoothie a.c. Especially Cohesion board because it has a firmware feature that lowers the laser power based on the actual speed of the motion. Without it (such as using marlin or supposedly anything except cohesion/smoothie) you'll get darker engraves around corners as the jerk/acceleration adjustment and the constant laser power will result in longer exposure of the material with the laser. Of course, I don't want to use anything except a duet, so I'm writing to ask i) does duet do this ii) if not, can you make it be able to do it?

    Thanks!


  • administrators

    This feature (velocity ramping) is already implemented in RepRapFirmware 3, but I didn't announce it before because I haven't tested it yet.



  • Interesting! Is it available yet? If not, do you have a rough idea of when it will be?


  • administrators

    It's implemented in the early RRF3 betas that I have made available (see the RRF 3 thread); but completely untested and therefore very likely not working properly. It's on my list to test this afternoon.



  • Interesting. Rather than buy an additional unit to test it, once I get my machine built, I'll tear down my delta, update everything and slap it on the laserbot to help test it out.



  • Given it might be a few days before I have the gear to test it, and I'd prefer to order whatever board I'll use in the interim, could I ask if you had a chance to test it, and how it went? I'm inclined to just order another duet on the theory that if you've already thought to integrate it either a) it already works perfectly or b) it probably will by the time the second board arrives here!


  • administrators

    I tested it this morning, and it's not working properly yet. I should get a chance to look at it again tomorrow.



  • So, as a general point, you're looking to continue to support lasers and related features right? Obviously you having started this task before I said anything is a good sign; even if it doesn't work yet, it will eventually, right? I really would prefer to use a duet instead of the equally pricy cohesion board that is purposed for lasers specifically, but otherwise doesn't look as capable as my duet. I just don't want to buy in for using it on a laser-exclusive machine to find you didn't continue support in that direction.

    Thanks for your time and help with this DC!



  • DC, could I ask you you to check out this forum post about duet's suitability for laser engraving? I think it might be helpful for you as you work on laser support, and it would definitely be helpful to me to know your thoughts on it:

    https://forum.lightburnsoftware.com/t/diode-laser-recommended-hardware-firmware/4405/6



  • I'm not sure if that comment that the Duet doesn't support G1 S moves to control the laser is accurate anymore as of firmware 2.02

    https://duet3d.dozuki.com/Wiki/Gcode#Section_G0_G1_Move

    Snnn In firmware 2.02 and later, when switched into Laser mode (see M452), this parameter sets the laser power. When not switched into Laser mode, and always in firmware 2.01 and earlier, it defines the move type (see the description of the H parameter).
    Very important! If you use M452 to put your machine into Laser mode, when upgrading firmware from 2.01 or earlier to 2.02 or later you must replace all S parameters in G0/G1 commands in homing files etc. by H parameters. This is because S is now used to control laser power, for compatibility with programs that generate GCode files for laser cutters.



  • @phaedrux said in Laser power adjustment/speed:

    I'm not sure if that comment that the Duet doesn't support G1 S moves to control the laser is accurate anymore as of firmware 2.02

    Oh cool! I'm not up to date on Duet/ RRF since firmware 2.0 came out. So then the question will become how well RepRapFirmware handles these lines such as G1 X0.1 S0.6 F6000 (that's Smoothieware syntax, or in RRF case S255) when receiving several thousands of them a second for image rastering.

    I don't know what the performance of that will be like.

    Speeds were slow when we tested it with the "Marlin-resembling" previous syntax, and to be clear, that was the source of my comments in the LightBurn Forum.



  • @raykholo ha! I expected you'd find your way here eventually, but not in practically real time! Small world of people with these overlapping interests I suppose. I appreciate your help so far!


  • administrators

    @raykholo said in Laser power adjustment/speed:

    @phaedrux said in Laser power adjustment/speed:

    I'm not sure if that comment that the Duet doesn't support G1 S moves to control the laser is accurate anymore as of firmware 2.02

    Oh cool! I'm not up to date on Duet/ RRF since firmware 2.0 came out. So then the question will become how well RepRapFirmware handles these lines such as G1 X0.1 S0.6 F6000 (that's Smoothieware syntax, or in RRF case S255) when receiving several thousands of them a second for image rastering.

    I don't know what the performance of that will be like.

    Speeds were slow when we tested it with the "Marlin-resembling" previous syntax, and to be clear, that was the source of my comments in the LightBurn Forum.

    You can choose the S value (255, 1.0 or any other value you like) that represents full laser power, see the R parameter in the M452 command.

    We are already talking to LighBurn about high speed rastering and I have proposed a laser rastering extension to the G1 command. See https://docs.google.com/document/d/1SMWFJUXfRSxe-p-veWEP-NU3A9ESKU_TVGB1Y1ADAV8/edit?usp=sharing.




  • administrators

    I'm sorry about that, I've updated the link in my post above. Try again.


  • administrators

    Laser velocity ramping is now working in the RRF 3 beta at https://www.dropbox.com/sh/3azy1njy3ayjsbp/AACquxr2m00eV568RZg5QG5wa?dl=0.



  • Perfect timing, just got a new low power uv laser to use with photosensitive pcbs - hope to test it asap


  • administrators

    The laser power is adjusted every 5 milliseconds at present during acceleration and deceleration. I hope this is OK. In the longer term I will probably make the adjustment interval the greater of 3ms and 5 cycles at the laser PWM frequency.



  • Wow this post has been so helpful! I will be following the progress with lightburn integration closely, I'm so excited to hear that you're already working on it. RRF has the potential to be outstanding with laser as it is with filament!

    Best,
    Stefan



  • Do you have any idea of when Lightburn compatibility might come to fruition? I'm so happy to hear that you were working on it, but I can't get a sense of if its moving along or just something that was discussed and left alone.

    Thanks,
    Stefan


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