Default 200 PWM Tuning for Smoothie Firmware results are better than tuned value

Machine: 80w CO2 laser

Board: LaserBoard

Firmware: I have a new board and I’m using whatever it came with

Prequel: I’ve been running lots of jobs (successfully) for the last couple of months using Lightburn since I got the Laserboard. This question is an exercise in tunning the machine as per documentation.

Problem/ Question: I’m going through PWM Tunning for Smoothieware; but, I think I’m missing an important step. I can’t attach pictures yet; so, I’m providing external temp links:

Output result for 200 & 3200 laser_module_pwm_period

Laser control panel

As documented in PWM tunning page I found that setting laser_module_pwm_period 3200 results in recommended current usage for a range of values: “…S0.4 is 40% and I would expect to see the needle somewhere around 4mA…”

However, as seen in the photo, the 3200 value reduces the quality of the output in comparison to the default 200 value. It seems that the DPI or interval is negatively being affected.

Is there another setting that I should be working with as well?


3200 may be too fast for the laser power supply to keep up with. I’d leave the PWM tuning at the default value unless your power supply is screaming audibly.

Thank you. I was trying to follow the document recommendation:
Every laser is unique and it is important to tune your PWM settings for best performance

Do you know if there is another way of fine-tunning or is this something that I won’t be able to do with my machine.

Truth is, this is the one parameter I tell people not to tune if you’re getting acceptable results with the defaults. The max I’d set that value to is around 400. Anything higher and the switching hardware in the LPSU can’t keep up. There’s also a nonzero start time to energize the CO2 laser. Low PWM periods can keep that from happening efficiently.

The biggest problem we run into with PWM tuning are laser power supplies that don’t behave properly with the default PWM setting. In that case we ask users to decrease the value and see if they get better results. We almost never suggest people increase the value.

loather, thank you for the detailed info. I will revert back to default 200.

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