Marlin and variable laser with min/max output

techtex · January 27, 2021, 3:54am

I am considering purchasing this software, but it doesn’t seem to something for my Marlin based with PWM laser. It can’t seem to control output level of the laser, only on or off.

I’d like to be able to set the levels (currently using the M106 and M107 gcode commands, and having a threshold for min, to still be able to use M106 with a low level that won’t etch, to avoid turning the laser all of the way off). (the delay of on/off with M107 makes the edges inconsistent for raster like etching)

I’d also like to be able to use the levels in order to etch images, which seems like it would provide better grayscale like levels to make better image etching.

From the old documentation below, it seems like the min power is not supported on GCode controllers (like Marlin).

github.com

LightBurnSoftware/Documentation/blob/master/Operations.md#min-power

[Return to main page](README.md)

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# Laser Operations 

The basic operations of any device can be categorized in one of two ways: Cut and Scan. These two options combined with variations in power and speed can achieve a variety of results.

Settings will vary from machine to machine and acrosss different materials. It is recommended to test your settings on a scrap piece of the same material as your final work piece before your final run.

Please Note: Cut speeds have been limited to 2000mm/s (or equivelant) This will prevent issues of entering too high of a speed which we are sure your machine will not like.

To the right of the cut window you will see 4 arrows. The up and down arrows allow you to change the order of the highlighted cut or scan layer, and the right and left arrows allow you to copy cut or scan settings into the cache, and write those cached settings into a cut or scan layer. Useful for copying settings from one layer to another.

* [Common Settings](#common) 
* [Line](#Line)
* [Fill](#Fill)
* [Fill+Line](#FillLine)

This file has been truncated. show original

So my questions are really:
Are levels already or soon to be supported with the M106 Gcode commands?
Will a low threshold be configurable to allow setting of a low threshold that would not turn off the laser, but would not etch? (from the old documentation that feature is on Ruida that a threshold will be used, if below that threshold/min value)

ender 3, creality 4.2.7 board, with th3d unified2 marlin firmware, Sovol 500mW laser via fan pins (with M106,M107 control)

LightBurn · January 27, 2021, 5:38am

LightBurn already sends power adjustment commands through M106 Sxxx (xxx being the power level). It is possible to get updates to the Marlin firmware that don’t have the fan ramping / delay in them, and those are much better for laser use.

techtex · January 30, 2021, 3:35am

I didn’t how to change the minimum from the Cuts/Layers Panel (shown below) when using Marlin. It is read only field there.

But thanks to your response, I did more searching and digging to find it in the Cut Settings Dialog, that I can only change when on Greyscale setting.

At least now I can see that the gcode is giving a variety of levels for the M106 Sxxx (power level).

Could there be a setting for Lightburn with Marlin, that still lets you set the min power when not using Greyscale too? That also may help me and others to overcome the fan delay by setting the min to something that still has the laser on, but not burning the material.

I will also look into more Marlin updates for the removing the fan ramping, but would you have suggestions for where to start?

LightBurn · January 30, 2021, 5:47pm

Even if I did force Marlin to never go below a certain power output level, there’s no guarantee that would fix the fan ramping issue. I suspect they always ramp the power change, not just from when it’s off to when you turn it on, but also between level changes, in which case your suggestion wouldn’t improve anything. The correct fix is to use a version of Marlin with the fan ramping disabled at compile time. Unfortunately I think that’s the only way to change that - a compile time switch.

system · March 1, 2021, 5:48pm

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