Yet another Newbie problem

I like lightburn and see a lot of good things I could do.

I cannot get the laser power above 20% even though it shows 100% in the line details window. I know it can go much higher as LaserGRBL allows it. I think I messed something up in Lightburn.

Hardware: 3018 CNC Pro with 5.5 Watt blue laser. Woodpecker 3.2A GRBL with 1.1f installed from the factory.

I read about M3, M4 and M5. I manually entered M4 at the console and I can see the laser changing intensity when it slows down. It never gets up high enough to burn.

Any help would be appreciated.



There’s a good chance it’s the same as with every other 3018 we’ve seen - Maximum speeds in the controller are set really low.

Read through this to see if yours is the same:

If that’s not it, let us know.

I got it working. Thanks. The speed was set to 6000 and I didn’t notice it. I set it to 500 and it is working well. I just need to tweak the power a little.

Great software… Thanks!


Follow up question. The minimum power is disabled at 0.0%. I need to be able to increase it so it will continue to burn thru corners and not leave a unburned gap like it is now. I read and read but could not find how to enable it. Any help appreciated.



GRBL (and GCode itself) does not have that level of control. Newer versions of GRBL, like 1.1h, have a global firmware setting for the PWM minimum, but that’s it. Using the GRBL-M3 profile will use constant power, so it won’t reduce at all for corners, but that will cause other issues (like overburnt, instead of under)

You can try increasing the acceleration in the controller, so it ramps up faster (bringing the laser power up quicker)

How do I set the M3 profile for this GRBL controller thru LightBurn software?

Here is a picture of what is happening.

Those lines are a little thick, so you might just be out of focus, which would cause similar effects.

To use GRBL-M3, just click the Devices button, double click your device, then choose GRBL-M3 instead of GRBL, and click Next until you’re done.

Thanks. I will change it to M3 and see which works better for me.

Is there a newer GRBL controller that works better with your software? If not what controller do you recommend for a hobbyist?

GRBL itself is usually fine, but the 3018’s are usually configured for CNC work, meaning really high steps-per-mm counts and screw drive, which means low maximum speed and low acceleration. CNC machines are build very differently than lasers.

I have a belt driven system coming which should solve this. I am at least working on the learning curve for Lasers and Lightburn. I really like the software more and more.

As a side note… I tried to install it on my Mac Book Pro and when it tried to find the board it crashed. I will try again in a bit.

That’s been fixed for the next release. For now, turn off Bluetooth and try again. Bluetooth headphones show up on Macs as serial ports, and they don’t close properly for some reason.

How much do you want to spend?

If US$50-80 is in the ballpark, there’s a number of LPC-1798 powered boards that will eat 328p-powered Arduino boards lunch.

Specifically, the Smoothieware-capable boards, but there’s a whole host of 32-bit boards available now at a decent price, and a tonne of different firmware that’s LightBurn-compatible.

Most come with built in drivers, or have plug sockets that you can reuse the ones that came with your 3018.

Personally I like the Smoothie boards and their clones - ethernet, web interface, SD card, bags of power, software-controlled drivers, smoothie’s awesome motion control, real-time parameter adjustment, fine resolution, you can fit a touchscreen and its compatible with a bunch of software for scheduling, etc. and will make your CNC stuff rock, too.

If this is the board you have, there’s potential for replacing the Arduino 328 with a Cortex-based plug-compatible controller on that mainboard and run a 32-bit GRBL port or something a bit more advanced.

Thanks Bo. I have a belt driven clone coming Monday. I will look to upgrade it and put the spindle back on the 2018 Pro. I have some small work cutting out servo trays, carving, etc. that it can do as it is configured now. I will definitely be looking at the belt drive’s board and want to upgrade it. Whatever I get for it will need to be Lightburn compatible.


My current board is a Woodpecker 3.2A GRBL (on the 3018 Pro).

Bo, What OS does the Smoothie 32 bit boards use?

The reason why I ask is does it have the same Laser power ramping issues as GRBL in M4 mode?

After some tweaking a receiving some help from Dave at I have the laser and 3018 dialed in with GRBL M4 driver settings. The diode is focused and generating plenty of power for my needs. The laser is a Sainsmart 5.5 watt blue diode. Acceleration and servo speed were the keys.

Light burn software is excellent! Great job folks!


Smoothieware, Marlin32, GRBL-LPC

There may be some other ports.

For my money, Smoothieware is a great firmware with some cool functions

OK. If you don’t mind I have two more questions:

1- Is there a US Dealer for a smoothie board?

2- Is there one made just for Laser Cutting/engraving… X, Y1, Y2 and Laser control?

Thanks again


No idea. You could look on their webpage.

Yes, they have a 3X model. Or they used to.

Or you could get a clone: Cohesion, MiniGRBL, etc. MKS, or any number of other brands.