Problems with C3D with LightBurn

Hi Guys!
I have been working for 4 weeks with the C3D card and the software Lightburn. We have rebuilt our laser to this system. Unfortunately, I am now reaching my limits.
The following problems occur:

  1. The lines are not pixelled to the end. (unequal offset see pictures)
  2. I found the problem with the pixels. We have to be able to pixel images at 400mm / s. Now I have read that you should not set more than 100mm. The solution would be a different firmware. I have now installed a different firmware and all settings from my txt config are no longer accepted. Is there a separate config.txt for each firmware?

We have installed an 80 Watt tube. Cutting works quite well, but unfortunately I have the problem with the pixels of pictures. Is there somewhere a setting which regulates the performance of the tube or affects the pixels?

Another point is the setting of the power amplifiers. Where can I change this in the config? Is there a possibility at all? I have to tell the software somehow how the drivers are set?

I hope my problems are sufficiently described here and someone can help with the settings.
Thank you in advance for your help.
(upload://zNFrTgdGG8CPTS4XejbVYhmP7eu.jpeg) ![Bild%2003|666x500]

By default, you’d have the smoothie firmware. Is that the first one you are referring to?
Did you try slowing things down and did that solve the problem? If not you’ve got more than one issue which should be solved before moving onto other firmware.

In order to help with this please tell us or show us (vis screenshot) what settings you are using.

The alternative firmware version is GRBL-LPC:

Setup for GRBL-LPC is done through a console command set or in LightBurn under device settings but this cheat sheet might help:

And if you mean stepper drivers and power level settings then you need to look here for hints and tips:

Hello Chris!
Thank you for your answer. Somehow I have other data than the one described in the table. I would like to upload all data of my config.txt, but I can only upload 1 image.

As Chris says, the alternate GRBL-LPC firmware should allow you to raster engrave faster than on the stock Smoothie firmware (although we are testing a fix to Smoothie firmware internally that should allow it to go much faster). GRBL-LPC is configured not from the config.txt file but via console commands or via Edit --> Machine Settings.

You have a larger machine so you would to change some values for motor currents (increase these to 1.2), and decrease the maximum speeds and acceleration substantially. You can use the machine settings in LightBurn to do this for GRBL-LPC in an understandable fashion, but usually we recommend people stick with the stock smoothie firmware (which will require loading the files onto the SD Card and keeping the SD card in the board) to tune their machines, and then transition over to GRBL-LPC once they have those values nailed and written down.

The two gentlemen in this thread, Christophe and Ray, have a larger machine with the LaserBoard and have spoken about the changes required in some depth. I would recommend reading this thread, and also going to their profiles, the activity section, to find the 5 or so other threads that pertain to this.

The only setting to speak of is the PWM Period or Frequency. For this you would want to read the PWM tuning guide in the forum FAQ section.

We really recommend starting on Smoothie Firmware and getting. I also noticed some errors in your Smoothie config.txt file, for example your steps_per_mm for alpha, beta, and gamma are all defined twice.

This is really the best suggestion I can make. Get the stock Smoothie firmware and config files from here: LaserBoard Firmware + Config Stock Files on Memory Card
Do not add any lines, just modify what is already there.

Change the motor currents, acceleration, seek rate, and max rate and max speeds.
Make sure your machine can jog properly without stuttering.

Run PWM tuning to ensure the Laser Power Supply is responding properly:

Then we will work on improving everything else.


Hi guys!
I have now installed the other firmware and created the GRBL. Now I can make adjustments under machine setting. But now I have the problem that if I want to write something in the configuration he sometimes breaks off when saving. If that happens, everything is gone and I can start over.
Another question that arises. Does the SD card under the firmare still to be used, since I describe directly over lightburn the controller?

The SD card still has the GRBL-LPC firmware on it.

yes, but if I reset the controller, the controller will continue to access the SD card, or will the card put the firmware on the chip on the controller?
I have the problem that the GRVL firmware crashes constantly when I make changes. I always get the error message when saving and then I start again, …

The sd card needs to be left in. If you’re removing it when it’s powered you’ve probably corrupted the sd card and will need a fresh copy of the firmware.

Hi Frank,

I do not understand which firmware you refer to when you simply say “the firmware”.

In my previous response I provided a detailed list of steps for you to follow that involve the Smoothie firmware. I would suggest to follow it.

It’s not a setting, it’s a performance limitation of Smoothieware itself. The public implementation only changes the laser PWM output once per millisecond. At 100mm/sec, with 0.1mm pixels, you are exactly at the maximum rate in the stock firmware. As C3D mentioned, there is a new version we are testing that increases this to every 1/4 millisecond, and has a theoretical pixel throughput increase of 5x, though we are testing to find the actual / practical implications of this.

Ruida controllers use an Altera FPGA paired with other micro controllers to accomplish this task with the speed required. A Cortex M3 is no match for that setup, so there are tradeoffs - the Smoothieware code is quite flexible, but it costs memory and speed. GRBL is faster, and uses less RAM, but it costs flexibility and the motion paths aren’t quite as nice. I’m hoping that the changes to the Smoothieware code end up creating a nice middle ground between the two, or possibly even just “Smoothieware Turbo”.

Also, instead of taking screen shots of your config file, you could have saved much effort (and squinting) by posting the config.txt file instead. Others here could then download it and use differencing tools to compare against their own files, instead of having to read line by line against multiple posted images.

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Good Morning!
Thank you for your answer!
We found a Ruida controller out of an old laser and built it into our system for testing purposes. Here we have no problems at all. I spent 5 weeks testing the C3D controller, or rather, trying to get a good run, without success. I’ve tried everything here in the forum, back and forth. I am very dissatisfied with that because there were no real useful results.
The very fact that the parameterization of the controller with the help of a txt. File on the SD memory card is running and can not be controlled from the computer, for me has a bland aftertaste. The Ruida controller works very well with the Lightburn software after initial tests. I think we will get involved in the system further. Only hurt that we have just reordered 3 controllers from C3D, …

Does anybody know how to see if my cohesion3d laserboard is in good healt???

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