K40 laser - Diode Laser?

I have the K40 Laser 40w unit. The gantry was so bad on it the I decided to change it with a 5w diode laser unit I bought on banggood. The metal unit that the K40 comes with was so limited that I removed everything and built a wooden unit only larger than the metal unit. I was able to increase the size and use the gantry from the diode laser and build some brackets for the K40 laser lens holders. So everything works good which took a little time to work out and I have now ordered the Cohesion board. Now my new thought is can I also mount the Diode laser along side the K40 laser head and use the diode when I want instead of the K40 laser. With everything working on the K40 laser side is there a say plug I could shut off on the K40 and turn on a plug that switches over to the laser?

One last question the banggood laser gantry bed has a larger foot print than the org K40 bed will I be able to in the lightburn software setup up the new dimensions and use the full size of the bed.

any thoughts would be awesome.


Added information pictures

Hi George,

Thanks for the pictures and information.

Can you also provide pictures of the diode module itself and the wiring attached to it? Advise of any specs, labeling, or markings written on it. If there is a sticker on the front of it, please send a picture of that as well and a link to the product page online would be helpful.

Running this with both lasers connected will be complex. Once we have a little more information, we can give direction on connection possibilities.

For the configuration changes, this modification may require a full revamp of your config file, including steps per mm, fine tuning for adjustments, and dialing in the physics values for your machine size, as covered in our Larger Laser Machine Installation Guide.

You will also need to account for the added weight on the gantry and adjust the configuration accordingly, to ensure that the head can start and stop without issue. This may require upgrading to heftier stepper motors and external stepper drivers, but will definitely require a lot of trial and error testing to get your settings dialed in properly.

Aloha Starla, after reading what you said this does make since I included pictures just in case. I took and brand new completely work diode laser unit. Removed the diode laser and installed it in the box I built. You reminded me that I did have to replace the stepper motors to NEMA 17 0.9 deg one’s the diode laser unit used different ones which were a nightmare to find. other than that I had to make brackets to mount the K40 lens units. The unit works 100 times better than the K40 gantry that was original. Basically it’s junk and ruined most of my projects. seeing that everything is working perfect I was thinking if I just made a bracket that mounted next to the K40 laser I could just switch from one laser to the other. But I did forget I used different motors. Does this change anything you were thinking and if not then I guess the easiest solution would be to just buy another diode unit there only $199. If I do that can use the light burn software on both. I have the cohesion card coming in for the K40 would I have to change anything on the diode laser unit for it to work. one other thing the foot print space on the new gantry is larger than the original K40 gantry will the light burn software allow me to use the whole area? Thanks for taking the time to read and respond to this.


Hi George,

Thanks for the additional photos and info. I appreciate your patience while getting caught up on posts!

I would need to see additional pictures of all of your machine components and wiring to give more details; however, the stepper motors I was mentioning would drive the X and Y axes from the LaserBoard. You may be able to use the module you have and just get these additional components.

The external stepper drivers, accompanying cables, and the additional power supply are not typically required but with your setup, using heftier stepper motors (like a Nema 23) would require all of these if you decide to go this route. For additional info: Cohesion3D LaserBoard Buyers Guide

More info on the external stepper drivers: LaserBoard Connecting External Stepper Drivers

For the connector:


The 3-pin connector is typically used for input signals “12V (VCC)”, “GND” and “PWM/TLL”. The 12V and GND need to go to a 12V supply, for which an adapter is required to convert the 12v DC.


PWM and GND need to go to “Alternate PWM Out” on the LaserBoard.

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You should also consider limit switches, if you do not already have them installed.

Set your homing direction based on your switch locations. The typical setup is to have alpha_homing_direction set to home_to_min and beta_homing_direction set to home_to_max, having origin at 0,0 in the front left corner.

LightBurn works with some pretty large lasers, so you should be okay. The Device Settings in LightBurn just tell it how big the work area is and do not affect the laser.

You may find these posts helpful for wiring and larger bed size:

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