Laser Focusing

Mostly Printed CNC - MPCNC Troubleshooting
#1

I thought there was a forum for just laser stuff, but I didn’t see it. I finally got my 2.8w laser hooked up as per the recommended specs. I have the “good laser a-11” board that vicious has, and same heatsync, so i was able to use the same mount to the machine.

My issue was trying to focus the laser to a single point on the wood… In order for me to do that, I had to basically unscrew the lens a few turns short of it coming free of the body AND i had it up about 3 3/8" from wood to glass of laser.

I’m not sure if these issues are correlated, but I was also not really able to get a good “grey”, it was either burning wood or not for the most part. I attempted to run the laser faster, and also to cap the max laser power in image2gcode with no luck.

Any suggestions would be fantastic… Let me know if any additional pictures or video would help! :slight_smile:

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#2

If that is the 3 element lens that is normal to be unscrewed that far. Your focal distance should be around 2 1/2? over 3 seems a little far.

What speed where you running at?
And how to do you feed your code to the machine? SD or Repetier?

#3

yes, it’s the 3 element lens (g2?). Feeding the code via Repetier. That picture i posted shows my tests at different speeds and powers… it looks like 620mm/m at full power gave the best results. I was going to try to turn down the power on laser driver and see if that helps… i don’t remember the amperage, but it was set to 6.5v as per a forum post by Leo69

https://www.v1engineering.com/forum/topic/mpcnc-2-8w-100-laser-add-on-complete/page/3/#post-7961

#4

G2 is a different lens. It has a slightly larger spot but is about 30% more powerful (and more expensive). But definitely worth the cost in my experience for engraving and cutting.

620mm/m is most likely way too slow. I am sure the guide said to set it at 5v and then around 2amps. I run mine a 2.2 amps i think.

I run my settings at depending on the material at 0-255 power, and 3000-4000 mm/m. Many people I have spoken to also get decent results at half power and half of that speed… around 1800mm/m.

Getting wood burning to look decent has been a long process for me and I am still working on it… but I am close.