Lightburn Camera and Bed alignment issues

Machine: Mophorn 40w CO2, K40 (most current model) with M2 Nano board

Board: Cohesion 3d purchased on 14 Apr 2020

Firmware: I have a new board and I’m using whatever it came with

Problem/ Question: I have updated the bed size based on all of the setup instructions. My bed size is 225mm on y axis and 300 on x axis. I have about 10mm to spare on each. I also installed the Lightubrn Camera and I calibrated the lens, but when I go to calibrate the camera to the bed, things go screwy. I follow the step to setup the image burn, and when I push the “Frame” button, it fames everything just like it is supposed to, yet when I hit the “play” button to begin the burn, that’s where things go wrong. It won’t cut in the area that it just framed out. It will start with the 1 and the 2 where the three and the four should be, then it will cut out the raster fill of the 3 and 4 right below the 1 and 2. then when it goes to cut the 3 and 4, they are outside of the cutting area. It homes to the proper location, and it origins at the proper location, but I can never get it to cut in the proper location. I have yet to finish the calibration on the camera to bed because I can’t even get it to cut the calibration points properly.

I am interested in hearing a fix on this as well.
Like Zeke I just installed a new Cohesion3D Laserboard last week and have had the same issue where it frames out the proper area for the calibration but the bunches everything at the bottom.

Tried it without the camera today. Just tried to engrave a five letter word. Put it at the bottom of the bed, so closer to 0,0, and it did all kinds of craziness. Engraved the first two letters, then the last two letters. First letter was in the right spot, second letter was at the top of the frame, didn’t even engrave the third letter, but the fourth and fifth letters were inclining upwards, almost as if it was trying to engrave them in a circle. I don’t get it.

Hi Michael, thanks for posting, and welcome to the forum!

Just so we can help you out without mixing up what Zeke is seeing and what you are seeing, could you create your own topic with the issue(s) you are having?

It will really help us focus on getting you the answers that are specific for you.


Zeke, can you make sure you are set to Absolute Coords mode in LightBurn? That is required when you do the camera calibration.

Also, don’t forget to click the Update Overlay button while doing the camera alignment.

If possible, please post a screenshot of the LightBurn window as well so we can check for anything else that might need adjusting.

Hello Pete, thanks for your reply. I have ensured that it is set to Absolute Coords mode. I can’t even get to the Update Overlay part as When I pull up the Tools menu, then go to Calibrate Camera Alignment, then I get the pop-up window to execute the alignment, but I can’t even get passed the part where it cuts the test dots. So I never even get the camera aligned, therefore it is pointless to update the overlay. I guess in trying to install the camera, I’ve uncovered a different problem that is separate from the camera. Lets take the camera out of the picture, unplug it, and not use it. I still have bed alignment issues.

I went to home, it homes properly. I went to origin, it origins properly. I put a word at the bottom left of the working area in lightburn, and when I hit “frame” the laser goes to some random area of the work space not anywhere near where it is supposed to. I’ve taken video of what it does. The first one is at this link and the second one is at this link

Just going to apologize in advance, this is my first ever youtube posted video.

Zeke, thanks for the videos… Let’s try to figure out what is happening. We noticed a whining sound from the motor when the head was traveling towards the front of the machine. This sounds like the Y motor is skipping steps. In the config file we set the default max speed, acceleration, and motor current optimistically, so they may need some adjusting downward.

In your config file you may need to increase the current and decrease max speed/ acceleration, in that order.

Check the section Updating the Config File in this guide for notes on how to change those values.

The other concern is the bed size - can you let us know if you’ve got the bed size set properly in both the config file and in LightBurn, as explained here?

Hopefully working through the above suggestions will get things running smoothly.

Pete, increasing the current and decreasing the max speed/ acceleration did the trick. It works just like its supposed to now.

I did follow the “Setting Up the Correct Bed Size” guide, and the settings are the same in the config file and in LightBurn. I went mm by mm and made sure I didn’t go too big. The actual movement of the head was about 225 on the X and 338 on the Y, but I just went with 200 X and 325 Y to make sure I didn’t go too far. That is in the config and in lightburn. They are the same.

I am sure I can probably tweak it a bit, but for everyone else’s future reference:

In the config file:

Beta_current, I changed from 0.6 to 1.0
beta_max_rate, I changed from 24000 to 18000
gamma_current was already set at 1.0, so I just left it as is (from when I installed my LightObject Z axis bed)
delta_current, I changed from 0.6 to 1.0
x_axis_max_speed I changed from 24000 to 18000
y_axis_max_speed I changed from 24000 to 18000

I was able to complete the camera alignment, burn the image where it was supposed to go (at 60% due to the z axis bed I installed), and even did a couple of test burns. Everything works.

Thanks Pete! It helps when you talk to some one who knows what they’re doing, rather than someone who just “tries to figure it out.”

I appreciate the help. Hopefully Michael can get h is working.

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