I often read about people setting the power to 12% or 15%,

Lasers
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1

I often read about people setting the power to 12% or 15%, my K40 has a potentiometer that can be adjusted and the power option in corel laser is always greyed out. Am I missing something or have other people got slightly different or modded machines that allow them to set the power using Corel Laser?

2

Not the K40-stock. Mine has a digital power thingy (0-100%), but it still has to be set by hand per-cut.

Both the Smoothie and RAMPS (and the DSP controllers) can change power during the cut, but the tools used are different than CorelLaser or LaserDraw.

3

some machine have potentiometer and vue meter, other have digital display in % setting. it does the same by limiting the max current (proportional to the 5V in).
PWM control is another %, not the same if you keep the pot. as ceiling.
Ex: if you set the pot @ 80% (5Vx80%=4V as ceiling) and 75% PWM, this would be equivalent of 3V.
you fix a ceiling to protect the tube life expectancy. one is set by soft, the other one is manually set.
When new, for the max current recommended for the tube, V was about 3.6V (can’t remember exactly).