I am considering getting a K40 type laser in the next few months, among the very many mods and improvements I will be doing is the addition of a Cohesion controler board. As I understand it, this runs smoothieware, I don’t know much about this and assume that Lightburn will sort out all the clever stuff. My main question is how to set a maximum power in the controler to extend the life of the tube, in GRBL i think this can be done using $30, does this work with the Cohesion board or is there another way to achieve the same result?
There’s an easy way to do this in hardware that we recommend. If your K40 comes with the potentiometer to set the power output level we typically leave this in place and that becomes your hardware maximum power output level. 100% power in lightburn means “whatever value you set on the pot”, so at that point there’s no need to play software tricks to limit the power.
If your machine comes with one of those digital panels to control the power we recommend replacing it with the potentiometer instead, as the digital panels aren’t accurate or linear. Of course, in either case you’ll need an ammeter to see how much current is being fed to the tube.
Recommended potentiometer:
I seem to recall store items for a multi-turn vernier knob but I’m not seeing it at the moment.
Ammeter:
Here’s a good how-to guide from one of our knowledgebase articles:
I need to figure out which one of these is actually appropriate for the potentiometer C3D sells, but one of these vernier multi-turn dials would be perfect on that pot.
https://www.bourns.com/products/potentiometers/turns-counting-dials
Thanks for the info, so I can connect the PWM from the control board and the potentiometer to the laser power supply at the same time?
That’s correct - the legs of the pot go to +5V, VIN, and GND on the laser power supply and the PWM connects GND and L-, in a nutshell.
Perfect, that’s the info I needed (I was thinking the pot and PWM went to the same terminal, I see my error now, many thanks)
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