Laser power adjustment/speed

clearlynotstef

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!

clearlynotstef

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

Phaedrux

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.

raykholo

@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.

clearlynotstef

@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!

dc42

@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.

A Former User

@dc42 said in Laser power adjustment/speed:

https://docs.google.com/document/d/1SMWFJUXfRSxe-p-veWEP-NU3A9ESKU_TVGB1Y1ADAV8/edit?usp=sharing.

requires access, you want do deal with the requests or make it public?

dc42

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

dc42

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

A Former User

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

dc42

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.

clearlynotstef

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

clearlynotstef

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

dc42

@clearlynotstef said in Laser power adjustment/speed:

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

LightBurn compatibility in what sense? I am fairly certain that firmware 2.03 and 3.0beta are already compatible with LightBurn. The difference is that 3.0beta implements velocity ramping.

TonyPagett

Do I need to activate this velocity ramping or does it just work as is when in laser mode?

dc42

@TonyPagett said in Laser power adjustment/speed:

Do I need to activate this velocity ramping or does it just work as is when in laser mode?

RRF3 implements velocity ramping when in laser mode, provided that you specify the laser power using S parameters on the G1 commands. So you don't need to enable it in Lightburn. RRF2 does not.

TonyPagett

@dc42 Thank you.
My next question is this. The following code moves the laser (CNC) in the defined square but only switches the laser on for the first line (or one side of the square).
M3 S255
G1 Y75.0000 Z0.01000 F2500.0
G1 X75.00000
G1 Y25.00000
G1 X25.00000
M03 S0

If I add an S command to each line it works OK

Is there a way round this?

dc42

Select "laser power sticky" in your M452 command. Preferably, don't use M3 to set the laser power, just use a S parameter on the first G1 move.

TonyPagett

Select "laser power sticky"

How do I do this?

dc42

https://duet3d.dozuki.com/Wiki/Gcode#Section_M452_Select_Laser_Printer_Mode