Laser will not burn

I am brand new to this, was using LaserGRBL on a 3018 Pro but it was not user friendly (note I was able to burn images with it) I downloaded Lightburn got it all loaded up and the laser will turn on and run but I am getting no burn in my wood piece. Need help! Thank you

I had lots of trouble getting started with my 3018 as well.

I had the ‘S-value’ problem and my requested speeds were in mm/s instead of mm/min.

What speeds are you asking your 3018 to operate at?
and
can you open the Console window and type $$ in there and grab all the machine settings. We can compare them.

What are the ratings on your laser diode?

Thanks for the reply.

Here is what I have:

$0=10

$1=25

$2=0

$3=2

$4=0

$5=0

$6=0

$10=1

$11=0.010

$12=0.002

$13=0

$20=0

$21=0

$22=0

$23=0

$24=25.000

$25=500.000

$26=250

$27=1.000

$30=255

$31=0

$32=1

$100=800.000

$101=800.000

$102=800.000

$110=1000.000

$111=1000.000

$112=600.000

$120=30.000

$121=30.000

$122=30.000

$130=200.000

$131=200.000

$132=200.000

I am not sure where to find the answer to the rating but it is a 5.5W Laser

I’ve done some custom calibrations on mine so if your finished products aren’t the size you expect them to be another adjustment can be made.

The $30 = 255 is one thing i’m suspicious of.

130, 131 & 132 are should be 290, 170 & 40 respectively.

Open LightBurn with your engraver connected.
along the top bar (left side) click ‘Edit’
wheel way down the list to ‘Machine Settings’ and click it.

A window should pop up and Show you $30 (Max spindle Speed)

I imagine it says S=1000. If it does, open the console window and type:

$30=1000

That should push that number into your laser controller for $30. You can check to see if that worked by entering $$ again. Worst case, if you need to change your settings back - you have posted them here for future reference (and you should probably make a text file, and note changes - and dates you change stuff,) so you can refer to them later if need be)

Let me know! thanks!

It looks like this controller is an 8-bit controller based on Arduino according to this snippet taken from this site. Hopefully I’ve identified the correct machine.

Controller Software: The Genmitsu 3018-PRO uses Grbl, high-performance open-source software for controlling movement, and runs on Arduino.

In that case $30 = 255 would be the correct value. You would then want to make sure that S Value Max in LightBurn Device settings is also set to 255. It defaults to 1000.

Hello PY,

I love your thorough posts and I really appreciate all the stuff you do here. I like that you dig into the guts of the things.

You’re right, it is an Arduino ATmega328P on the board. It is 8 bit RISC so, I pulled the datasheet.

I’m not refuting or arguing at this time as I would need to dig deep to see where it’s stored but Section 7.2 of the Datasheet is pretty interesting.

I have a SainSmart 3018 on my bench so I figured I could help. I don’t have the pro model with the limit switches but I’m cutting stuff and learning quickly.

I believe the number merely has to match and I’m under the impression that the actual value is not critical. If there’s a good reason to change I’ll change mine to 255.

SainSmart said this in their document linked above:

But otherwise, leave it alone since you are probably already used to it being at 1000 anyways.

I could be wrong - I didn’t write the controller logic. :smiley:

Hey John. I wasn’t even considering the datasheet for the ATmega328p when responding. I just happen to be familiar enough with GRBL and how Arduino boards have been used for these to know that $30=255 has been how that has been traditionally configured.

PWM for laser power controller is tied to Digital pin 11 on Arduino Uno. The value for this pin is set by using analogWrite() function which takes values from 0-255. This is where the 255 comes from in $30=255 and is stored as an int value type for the function.

Check out this excerpt from The Arduino Site:

Arduino and PWM

The Arduino IDE has a built in function “analogWrite()” which can be used to generate a PWM signal. The frequency of this generated signal for most pins will be about 490Hz and we can give the value from 0-255 using this function.

analogWrite(0) means a signal of 0% duty cycle.

analogWrite(127) means a signal of 50% duty cycle.

analogWrite(255) means a signal of 100% duty cycle.

On Arduino Uno, the PWM pins are 3, 5, 6, 9, 10 and 11. The frequency of PWM signal on pins 5 and 6 will be about 980Hz and on other pins will be 490Hz. The PWM pins are labeled with ~ sign.

The importance of $30 and S Value Max matching is about ensuring that the range of values scales the same for both LB and the controller and from that perspective alone the actual value itself is not important. However, in this case the $30 value for Arduino is significant.

How 1000 then got standardized for later implementations I don’t understand. It’s not a particularly computer friendly value. I suspect it was to make scaling against 100% easy to understand. But purely speculating. :man_shrugging:

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Folks, I am a bit confused by the above settings, it appears the contradict each other. Please advise on the proper ones to try and I will and report back. Thank you all for your help!

Gary, there was a discrepancy in John’s understanding and my own but I think we’re in agreement now. I can’t speak for John so I’m sure he’ll speak up if I’ve misstated.

Leave $30=255. Update S Value Max to match to 255.

changed it to 255 no luck.

What does this mean? What are you not able to do?

I’ve now reviewed the start of this thread. Can you describe in detail what problem you are experiencing?

no I Was able to change it to 255 but it did nothing. Problem in a nutshell: Laser runs but does not burn.

Can you give me the bag full version of this? I can’t even begin to speculate where this is.

What are you trying to do? What happens when you try to do that? What’s complicating the completion of doing that?

Provide as much detail as possible please.

Sure can: Genmitsu 3018 w/ 5.5W laser module kit by SainSmart. I can import a drawing I want to burn into wood, I center it where I want hit run and the laser turns on and it runs but there are actually 2 issues: 1. It starts in the front left corner, not in the center where the drawing is and 2. It does not burn at all… Thanks for the help I am totally lost here

Okay. That sets my bearings. Let’s address one issue at a time starting with the not burning issue.

When you say it doesn’t burn, do you see that the laser has fired at all? Or there’s no light at all?

Please attach a samlple .lbrn file (a saved project file from LB) that exhibits this behavior.

Laser comes on an appears to be working fine just no burn. File attached, I hope.
YDA.lbrn2 (45.9 KB)

Got it. The not burning issue is almost certainly your speed/power settings.

You are currently configured for 6000 mm/m and 20% power.

Start by reducing speed to 500 mm/m. Test a burn. Increment power until you get an acceptable burn. From there you can tweak speed and power to your specific material and laser.

As for your movement issue, this is very likely a gap in how you are setting machine origin. I’m going to assume you don’t have homing switches. If you do, this guidance changes. Just let me know.

Take a good look at this section of LB documentation:
Common Grbl Setups - LightBurn Software Documentation

no switches and yes it is burning now but light, do I increase that number to darken it?

There are a lot of factors in getting a good burn but your 2 major controls are going to be speed and power. The higher the speed, the more power you’ll need to get the same amount of burn. Similarly, the slower you go, the less power is required.

Imagine you’re pressure washing a driveway. High pressure slow speeds will result in a more forceful action. Less power at higher speed will have less impact.

Make sure you have a solid grasp of focusing as well. That’s incredibly important to get a good burn.

I had a thought about this and I wanted to circle back.

If the base pwm frequency is 1000Hz (980 is pretty close-2% error) and the scale of spindle speed is 0-1000 then the pulse width in milliseconds is the commanded spindle speed which one could readily read/verify with an oscilloscope.

Agreed, not computer friendly - but super technician/hobby friendly.