Mount a laser with GRBL32bits board

Warning (even if these risks are low, you must be informed)

The use of a laser can be dangerous, you must take all measures to protect your eyes by using glasses suitable for the type of laser used and be alone in the room where the laser is on.
Depending on the materials in contact with the laser there may be very toxic fumes, avoid engraving on materials without first inquiring. The room must be ventilated in all cases.
As you know, laser burns material, so there is a risk of fire during the job, do not leave the machine unattended.
Do not try to burn reflective material which could deflect the beam anywhere.

What can we do with this type of laser?

This type of diode laser can only cut thin layers of plywood, balsa, cork, paper, cardboard … with several slow passes, it’s not really made to cut.

It is basically designed for engraving, even for the most powerful diode models.
If you want a real laser cutter, you have to invest in a CO2 laser! (Machine dedicated to that, not the same budget!)

 

Hardware :

A laser module : Attention, some sellers play on the words, some are sold for 15w, in fact it is the electric consumption, not the power of the laser! The two links below are good value for money and tested by the members of the forum and i.

Blue laser module 5.5w 450nm ou Blue laser module 15w 450nm

A 12v 6A minimum power supply

12V 6A power supply

A printable laser module holder for RS-CNC32:

Laser holder by Nicoco

Laser holder by Daniel

Wiring diagram

  • Don’t need shielded wires
  • Use wire sections similar to those supplied with the laser

GRBL Firmware

If your GRBL firmware (on the STM32) is older than January 15, 2020, you must update it, because firmware has been optimized for use of laser:

GRBL Firmware, Easy way

GRBL Firmware, Custom way

Once update done, launch command $RST=$ so that all the new parameters are activated (if you had customized parameters via GRBL commands, you’ll have to do it again)

Focal adjustment

Adjusting the focal length is essential to get the best out of your laser. Two possibilities:

If your laser does not have an adjustment ring at the level of the lens, it was delivered with a shim, it is just necessary by manually adjusting the height of Z axis, come to stop the lens on the shim placed on the material to be engraved.

If your laser has an adjustment ring at the level of the lens, there are different ways to adjust the focal, I proceeded like this:

  • Using a rule or a homemade shim, adjust height of the lens relative to the material to be engraved (I chose 40mm, but you can choose another height)
  • Start an engraving job
  • Pause the job via the TFT (the laser turns off when it is paused)
  • Turn the lens wheel a little
  • Relaunch the job, and pause to see the change in color
  • Repeat the operation until the darkest engraving is obtained
  • Once the optimal focal length is obtained, you no longer touch the lens setting, you just have to put the laser at the right height in relation to the part to be engraved for each job.

Example of preparing an engraving file

There is a lot of software for this use, here I show you an example with free software, open source and very simple to use: LaserGRBL

Once LaserGRBL downloaded and installed, open it:

  • Open an image file (it can be a photo) File> Open a file
  • On this tab, you can adjust the brightness, contrast, ect.
  • Then choose “line by line” and “diagonal”
  • You can choose the definition by the number of lines per millimeter, obviously, the more you put, longer it will take to engrave
  • Then click on “Next” at the bottom right.

Here we will adjust engraving parameters

  • For the speed, I put 1300mm / min to engrave with my 5.5w on MDF, speed will be different depending on the power of your laser and type or color of material to be engraved.
  • Laser On, we put “M4”, laser OFF “M5”, S-MIN “0”, S-MAX “255”
  • Then you adjust the size of your image to be engraved.
  • And click on “Create” button

All you have to do is get your file

  • File> Save program
  • Put the .nc file obtained on your SD card and put it in the TFT of your CNC!

Laser use

Note: laser mode in GRBL must be activated to engrave ($ 32 = 1) It’s activated by default in the latest firmware, but check your configuration with $$ command.

Note2: Router/spindle switch must be turned off !

  1. Adjust height of your laser in relation to the material to be engraved and put it at the point of origin XY
  2. Turn on the machine and only then turn on the laser (with switch integrated on laser module)
  3. Check on TFT info screen that the 3 axes are indeed at 0 (otherwise press the button Set 0 XYZ)
  4. Put on your laser protective glasses
  5. On the TFT, go to Mill> SD> your file and go!
  6. Once job is finished, first turn off  laser before turning off the CNC !

If you have technical questions, please use only  forum board (international English section)
Comments are reserved for information … or congratulations 😀

Thanks and good job folks  !

Romaker

8 thoughts on “Mount a laser with GRBL32bits board”

  1. Chapeau bas excellent travail.
    Merci pour l’avertissement sur la puissance des lasers, je me serais surement fait avoir, ma cnc est terminé et je commencer a regardé pour l’équipé de ce système, je cherchais sur 20w bleu, c’est le max que j’ai trouvé, mai je me demande maitenant si c’est juste, à prospecter donc.

    1. Merci Thierry,
      Je ne suis pas un expert en gravure laser, mais suite à la demande, je m’y suis mis, j’ai trouvé ça cool, et je partage en tuto 😉
      Bonne soirée
      Romain

  2. Tout d’abord un grand merci pour ce projet, j’ai cherché un bon moment une CNC diy. Et voilà la machine rêvée !!
    Chapeau bas pour tout le travail fourni et pour l’accueil.
    Je suis en train de préparer ma commande pour cette machine. Juste une petite question : y a t’il vraiment une différence entre les 2 lasers proposé ? Car le tarif est du simple au double, la puissance est elle en rapport avec le tarif ?
    Merci d’avance

    1. Bonjour Thomas,
      Merci pour les encouragements 🙂
      Oui pour les lasers c’est la puissance qui fait le prix, j’ai prit le 5.5w, il va très bien pour la gravure.
      Bonne journée
      Romain

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