Laser Power dwarfed after GRBL Firmware flash

Just snagged a DIY Diode laser from EBAY. the cheap China kind. Came with Benbox etc. I hated benbox so I updated firmware to work with Elekscam. This software operated the laser smoothly in regards to speed and power for simple images. Photos are my target output so i decided to get lightburn. It does technically work with that firmware but speed was just never there. Also the laser wouldn’t work. After seeing so many posts about settings i noticed i did not have $30 or $32. This prompted the update to GRBL 1.1

Since this firmware update my speed was WAY off. I managed to change a few settings and write a few things into the controller to match its speed output on Elekscam. What I can’t seem to match now is the Laser power. Prior to GRBL 1.1 update I could burn at 20% however after this update 20% is more like 50% I have played around with settings to get images and most look 100% better than Elekscam but the faster i go the worse quality i have. Also the slower i go the bigger burn blobs i get. Below are my settings. I can’t seem to locate a close resembled problem or at least a good fix.

Speed: 10mm/sec
Depending on the image i can make this good or bad in a heart beat while burning the same image but with different settings in GIMP. 50% seems like a lot and it was burning normal at 20% prior to firmware so I was wondering if anyone had any idea on how to update this.


When you make a software change you should spend a few and go through the setup for your laser. It looks like you probably have $30 incorrect, but other information is missing to do much…

Go through the Lightburn grbl setup procedure it should fix up the $30 issue and it’s associated setting in lightburn. That would probably fix your laser problem.

Both machine and software have to be configured the same. Are you using mm or inches?

Good luck


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I will double check. For what it’s worth it was at 1000 rather than 255. I read that the 8-bit system was a pain. I changed S value to 255 as well just to see if there was any difference and there hasn’t been. It will be a while before I can hop on and plug in. I appreciate the quick response and will report back an update when I can.

This is my first laser. Super fun to play with. Soooooo many settings to fine tune lol

Also I’m using mm

The pwm is based on the word size of the controller, as a general rule.

The difference in the ‘resolution’ of the pwm is dependent on how many bits are used in the control of the pwm signal.

8 bit only have 256 ‘steps’, the 8 bit limit… if you expand that to 16 bits you have 65,536 steps and a 32 bit has over 4m (2^32)… the control you get is more finely adjustable…

65k settings is more than enough steps for me… when you think the laser is on or off anyway, this may give you finer control… but if I change the pwm ‘power’ by 1% that’s one percent of the range or 655 ‘steps’ in a small change… 32 bits 1% of that is 4,294,967…

How much ‘resolution’ is really actually useful or reasonable…?

I’ve left off the period or the pwm ‘base’ frequency, that’s another option…

Lots of variations to ‘fool’ with… just keep in mind the basic operation of the machine and what are reasonable expectations …

When you get a chance to get back to it, let us know how it works out…

Also make sure you check the ‘S-value max’ setting in the ‘Device settings’ this needs to be equal to the $30 entry…

Good luck…


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