Hi there,
currently i am trying to set up my new k40 laser. Ive done some engraving with the stock mainboar and K40 Whisperer. To control the laser via lightburn, i have installed the MG3 board from awesometech yesterday. Since then my engravings have a massive loss in details (missing dots).
I have tried to increase power and or speed and the missing dots are coming back at higher power but then i get overburn in high pixel areas. I’ve spent the whole morning aligning the system and the problem is still there. So i decided to setup the old mainboard again and now the problem is gone.
After some research i think it comes from the PWM-control of the new board. The tube has to be fired for every dot again and again and with the stock mainboard the tube is always kept on but on a low level so it can fire in a shorter time.
Can someone confirm that and tell me how to setup lightburn/mg3 board to get the same behaviour like with the stock board?
It lases, when the L input of the lps goes low, this is the laser enable. Only an RF excited tube can be held at a higher state for a quicker response.
If you have a manual control, it’s probably connected to the IN of the lps.
Double check how the pwm is configured. Since the operation seems to work backwards, it might be inverted, just a guess…
You can check the pwm with a voltmeter, the pwm should be ‘active’ when it goes low, so the displayed voltages will be inverted… If low is active, then with a 25% pwm, it will only be low or active for 25% of the time… you should read 75% voltage, like .75 * 5v or about 3.75 volts.
thank you for the answer. the pwm seems to work, i have tried to engrave with grayscale now and that works perfectly smooth.
on the awesometech page they say:
A trick that we can apply is setting the $31 minimum laser strength e.g. $31=5 which keeps the tube on but lasering is too faint to affect the work piece.
Sounds like you have it working? What was the fix…?
This isn’t done anywhere that is known to me, probably because it’s practially impossible for a dc excited laser.
When a tube lases, it lases at 100% it cannot lase at any other state. If you set your pwm to 40% it’s ‘lases’ 100% for 40% of the time. There is no power control over the laser, just power/time.
When you run a tube near when it resonates it will substantially shorten the tube life, because it isn’t lasing and will break down the co2 much more quickly.
The quote didn’t come through, so I don’t know what you are referring.
i did not fix it. i just tried engraving with grayscale instead of dithered now and this works very nice. but i also want to get the same results as with the k40 whisperer.
so these are the facts for now:
I’ve dithered a picture in lightburn and saved this as a gcode file for the k40 whisperer. When i run the laser over k40 whisperer with this gcode, everything works fine, every dot gets engraved.
When i run the same gcode over lightburn, many dots are missing, seems like tube isnt firing fast enough.
What speed/power are you running… I think that board does a minimum power?
I’m not familiar with that board, but I’d think it is probably something configuration wise on the controller. There is no way to test it except with Lightburn or some other laser software.
Do you have S-value max, $30 and $31 as described?
Does this board come specifically for the K40, configuration wise. ?
For grayscale i am using a min power of 8,5% and max power of 16%
I took a picture of a grayscale test that i have made to show the difference:
Top bar: Dithered (Stucki) with 16% at 4000mm/m
Bottom bar: Grayscale with 8,5/16% at 4000mm/m
Yes, i have also tried to increase the $31 parameter but there is no difference.
For now i think i am okay with these circumstances. Getting really nice results with grayscale
Maybe i will send an mail directly to awesometech. Maybe i am wrong but i think they made the board for k40 only.
Possible, but if that were the case, you wouldn’t need to be able to change the configuration.
Ask them if you’re expected to modify it from it’s supplied configuration for the K40…
Any way you represent speed is understandable, but generally as you speed up, like with a co2 laser, the speeds are expressed in mm/s, instead of 4000mm/m or about 66mm/s.
8.5% power is in the range a co2 won’t consistently lase, so be careful with the lower power. I think I usually engrave around 200mm/s at around 20%, maybe speeding it up and see if that improves/changes the end product…
The grayscale is actually created for a 3d type engraving with a co2… is that what you are after?
I know others here have a similar setup.
It pays to advertise… might want to add re-word the title to include it’s an upgrade to your board… and specify the board. Others that have that board are more likely to want to check it out…
Good luck… keep us advised of Awesome techs response.
Nope, i am not after 3d engraving. I was mainly engraving pictures in the last months and now i’ve bought a K40 to do cutting stuff but discovered that engraving with other lenses then the stock lense can give good results.
So my main goal is engraving pictures on wood which works with grayscale for now. I was also engraving on slate plates with the diode laser. But i think slate wont work with grayscale. So i would really like to solve the problem.
I think i will start a new thread for this issue but maybe you got an idea because i am already facing a new problem. Do you see these little white bars from top to bottom every few centimeters?
Any idea were they come from?
