Well, I ran into amother problem, but I will take it to the Cohesion 3d g+ group
What issue are you running into now @Ryan_Branch ? I just made the change to my config, and can confirm that I’m getting better results with engravings now as well. I’m going to test adding the pot back in again, with it connected I seemed to be able to get back up to 250mm/s engraving speeds without the stutter.
Sorry for the late reply @Robin_Sieders I moved the conversation here. https://plus.google.com/101842495658501740623/posts/3D3RksJ5ZQa
I am curious about your setup though and what your settings are in smoothie! I don’t think we have done any raster engravings that fast yet.
@Ryan_Branch I cannot answer in that forum for some reason. First K40 are definitely not linear in any shape or form. Do not expect that the darkness will be proportional to the PWM sent. Second did you set the PWM period to a reasonable value? I find 200 seems to work better than smaller values.
laser_module_pwm_period 200
@Wolfmanjm Not sure why you can’t answer in the Cohesion3D Group, I checked and you are definitely a member. Feel free to put up a test post or comment on the hardware FAQ thread there to test.
@Wolfmanjm when you say that the K40 vs PWM is not linear do mean because of all the physical variables (wood etc) or is the non-linearity in how the PWM is set in the firmware.
Btw here is some theoretical validation on the 200us setting you suggest:
@Ryan_Branch I finally got around to testing with the various things connected/disconnected. I was mistaken in thinking I had hit 250 mm/s since upgrading to the cohesion board. My max seems to be 100 mm/s @ 5 to 25 % power if I want to keep lighter details. I don’t get very good variation when I have the pot connected, the dark areas seems to engrave at whatever power I have the pot set to, no matter what settings I enter in Laserweb, so I removed the pot from the equation again. I’ll upload a picture of my tests so far, when I get home, to show what I’m talking about. Going to test out adjusting the PWM period as @Wolfmanjm suggested as well to see what difference that makes. Overall I’m pretty happy with the results I’m getting right now though.
@donkjr afaik the shade is not proportional to the pwm. the pwm is linear, but shade is not proportional to the pwm i see this also in led based lasers although they seem far more proportional than the co2 lasers. also i got the 200us period from your work 
before that I got no power variance at all, it was either full on or full off.
@Wolfmanjm your saying that the non-linearity is in the laser power supply or laser ionization characteristics or both. Also how materials burn is not linear. Makes sense …
BTW connecting to 'IN"with a level shifter creates another non-linearity" …couldn’t resist.