Losing steps in Y - in one direction

I am running into probably 10 hours of effort trying to figure out what my ‘cobbled together’ laser can do.

It is a 2500mW, 2-pin laser mounted on a 3D printing chassis. I’m using a Sainsmart RYC-GRBL-V2 controller board which I was able to update to GRBL 1.1F.

For background - I have a CNC router and a 3D printer - so… I’m pretty familiar with gcode. I did not create this thing - a friend gave it to me (that’s so I don’t have to take responsibility :smile: )

My list of troubles…

  1. I am struggling to figure out how to focus this laser - it’s a variable focus device and it SEEMS like the shape of the spot is more of a line than a dot. I can get it to burn wood and painted tiles (the 2 things I have tried so far), but… I’m thinking maybe my focus is a problem?
  2. when I run the test pattern (matrix of squares) I have to slow down to like 200 mm/m to get any kind of marking. And the laser only seems to mark the material (wood and tile) at about 70-80% - anything less there is no burning or other marking… does this seem reasonable for a 2500mW laser? EDIT - in both tiles and wood - there is no difference between the colors… when it burns it’s black… otherwise it just doesn’t burn
  3. I took something I had cut on my CNC and tried to burn it with LightBurn. It was telling me it was a 3.5 hr process (100mm x 75mm) and as it progressed through it - it started losing Y steps… the X stepper got ‘surface of the sun’ hot. I tried twice - and both times the same net effect. I even tried importing a .ngc file and it and it was doing great until it started to do an frame around the image. It started in the X direction… burned across no problem, shifted to Y and made some funny sounds and only progressed maybe 25mm thinking it was finished, burned across the X again with no problem and then started on the Y, this time now funny stepper sounds and it was on its way to crashing into the stop. Possibly belt tension? or stepper timing? or… sun spots (I am a computer guy - whenever I can’t explain a problem, I blame sun spots)

Any suggestions would be great - my hair has thinned with age and I’m close to being bald from this laser (ripping out hair tufts)


You laser only has power to it?

Most of these have three lines, power and the PWM signal. How is this connected to your saintsmart board?

You controller may be able to control a 2.5 watt device. Keep in mind that with ss lasers it’s measured in input power. If you have a 20% conversion, you’re doing well, so the power out of that laser could be less than a 1/2 watt.

However you are burning wood… What type of laser and what do the specifications tell you about it’s operation?

It sounds like this has never been functional, you are kind of starting at a major disadvantage.

One thing I’ve learned in 50 years of fixing stuff, is walk away before you get to the frustration point. Have a cup of coffee and relax. Think about the problem… :slight_smile:

Just to ‘close the loop’ on this topic… I think my issue was stepper connectors. As stated - this system was ‘cobbled’ together and after having trouble with the ORIGINAL connections - I modifed/bought new ones and that seemed to be better… but obviously not perfect. Yesterday I made them ‘perfect’ (new connectors… AGAIN) and then… I seem to have messed up my laser module (see my latest post).

Sigh… this ‘free laser’ is starting to become expensive…


They are expensive when they aren’t free :frowning:

I’ve seen some of the 2 pin ssd. They are generally just connected to the PWM since the current is relatively low. This is the driver circuit from my cnc3018 Woodpecker V3.4 grbl controller as an example.


The IRF540 is good to 33 amps… properly mounted… 2500mw would be about < 210 ma at 12 v.
Thinking about it, I ran my spindle (more current) via that circuit, so it shouldn’t be a problem.


For focussing:

What I found easiest is to use the “ramp” method. Place a piece of wood in the form of a ramp, so that one end is close to the laser head and the other is farther away. Burn a line along that direction. You will see that the line goes from “not focussed enough to mark the wood” to “wide” to “narrow” and back again. Find the point where it is the narrowest, manually move the laser head over it and measure the distance. That’s your focus distance.

If you laser has an adjustable lens, note that this not just changes the focus distance but also the focus depth. Meaning the distance range over which the laser is focussed enough to be usable. At one extreme, the focus point is very tiny at exactly one distance, at the other end it is somewhat small over a wider distance. You need the latter if you want to cut something through and not just mark the surface.