I happened to watched a video https://youtu.be/AgzPx4wxpXw?si=4Xxq4X3yrkDmJCXN
Apparently the S Value can be edited to 10000 instead of the default 1000 to gain a signifcant increase in power output. I tried it following the video instructions and true enough the output is totally crazy! My concerns are if this will affect the laser module in the long term?
I think what the video says is your Lightburn S Value should match your $30 machine settings. Not that you can simply Increase the numbers to get more power from your laser. Even if you could i would be very weary of doing that. And yes, you can change the DEFAULT S Value in Lightburn from 1000 to 10000 but only if 10000 is what the $30 machine value is.
That is not how the S-value works, The max value is 1000. for some lasers the max value is only 255, these are only discreet increments between zero and 1000 to tell your laser how much power to output. Increasing that number above 1000 does not increase laser power.
I did change BOTH to 10000. The output is like turbocharged. I could double the speed for cutting and reduce the usual power and increase speed for engraving.
I cannot understand how the changes affects the power output so much, hence I asked in this forum. Hopefully I can get some understanding.
Thanks, I have replied above.
Absolutely impossible. If you change both values equally, the physical output is exactly the same. It’s 100% PWM signal which means 5V for most lasers. If the laser gets 100%/5V, the diode fires at full power, there is NO CHANCE EVER to increase this. Not with any software setting.
The only change that you now have is that you have a more fine-grained control of the laser power. You now can set it to 50.555% instead of 50.5%. That might make sense in some rare use cases, but is useless in most scenarios.
I watched the video, didn’t remember anything about these values, it’s mostly on air assist. Could you give me a minute/second into the video to hear what he has to say about changing these?
I have to agree with @misken about it being absolutely impossible.
The S-Value Max is actually a maximum spindle speed settings that are sent to the controller. The only difference is what you send the controller.
With a zero in $31, at 50% power, using S-value max at 10000, it will send an S5000 code, set to 255 it will send an S127. Grbl uses the maximum/minimum spindle speeds, and generates the difference between them linearly.
Each of these produces a 2.5V (50% of 5V) output of the analog output.
If it’s pwm, which is becoming lower cost, produce a 50% pwm to the device. If you’re driving a digital device, such as an led or rf co2, it needs to be a pwm type of output from the controller. Analog or pwm is fine for a glass tube co2.
It’s been a while since I’ve even referenced gcode but I think these are the values that are sent. In any case, we’d all do this and not spend a bunch of money on a more powerful laser. There are plenty of people here that can correct me if I goofed anywhere.
Personally, I think they should advise you to set $31 (minimum spindle speed) to zero. Default grbl outputs about 0.02V (~0.01% power) at minimum spindle unless it’s value is set to zero. You want the laser to turn off, so this needs to be zero.
What this does give you finer control of the output. I have 8 bit and 16 bit controllers. The 16 bit machines give me over 32k steps…
I have yet to find a material that I can do a grayscale engraving with any kind of reasonable range in the black to white gradient. Most of these materials will compress the grayscale rang over a much smaller range.
I don’t know of a material that allows a good grayscale across 255 steps, so I see no real improvement in having 32k steps.
Good luck
Well, if things started with $30=1000 and S-Value Max=255, then changing both to 10000 would dramatically increase the maximum possible laser power. Don’t know how LightBurn would have that setup, but we’ve seen stranger things happen around here. 
Wouldn’t improve the power any more than setting just S-Value Max to 1000 and matching $30, but …
Thanks for your reply.
When I watched the video, it was kind of weird. But I thought it might be worth a try. I have a Sculpfun 33W. currently to cut 3mm birch/bass ply I would set 465 spd and 49% power x 2 passes to prevent charring. I changed BOTH machine and device settings to 10000 and was surprised to see a dramatic difference. So I changed speed to 875 and 35% power x 2 passes and I get very clean cuts. I know illogical but there is definitely an improvement over the speed and power. My concern is whether this would have any long term effects on my laser module.
That’s why I said that it’s impossible if you change both values equally. Of course, if the setup was incorrect before and you correct it, then you can get a power increase. LightBurn sets the s-value to 255 if you add the laser as grbl-m3, which many people do, or better to say, what LightBurn automatically does, if it doesn’t recognize the grbl version correctly. This sometimes happens with newer lasers because manufacturers develop their own firmware versions and change the version string.
So people need to always make sure the laser type is set to grbl and nothing else.
That’s no issue. Since you had an incorrect setup before and weren’t using the maximum power of the laser head and now you do. You never can use more than 100% power, that’s impossible.
That being said, running your lasers at around 50% should give you a long lifetime. Never exceed 90% is the most common advice.
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