I did this quick test before running my next batch of cowbells, I just draped some done-with customer prints over the bell clamps, focused the lens to it and this is the results--
first off, the paper is lying a bit, I typed 8% but turned it down and ran it at 7% power, and 500mm/s. Gap space was .08mm, and I used a 3" lens...
first shot shows the paper, not really flat, 2nd shot shows the results, note the power fell off at the "8%" where it was a bit out of focus.
It does show that the power is pretty low--
lp1.jpglp2.jpg
So I drew 3 quick rectangles, and cut them at 300mm/s and 7% power, with both MIN and MAX settings at 7%-
I did this on purpose, I'll explain shortly...
1st pic was during the cuts (had to act fast with the camera!)
lp3.jpg
And here's the cuts. Now, notice the corners are cut thru, but not the long straightaways--
lp4.jpg
I turned the paper over to better show this--
lp5.jpg
--the reason I set the MIN and MAX settings the same was to explain what these settings are for, as many people don't seem to really know--
The corners cut thru is because the machine was in the process of decelerating toward the corner to change direction, and then acclerating away from the corner. During this time the machine is obviously running slower than 300mm/s, BUT THE POWER REMAINED THE SAME-- so the corners burned thru-
--This is what the MIN power setting is for, to lower the laser power when it's in decel/accel mode. Had I set the MIN power to around 5% (roughly 70% of 7%), the burn thru would have been much less or eliminated. However, at this low of power setting, the laser may not have fired at 5%.. So the trick is to experiment at 'real' power levels, such as vector engraving outlines in wood, change up the MIN power setting until the burn around the entire square is nice and even. Make note of the percentage differential, and use that as a starting point when vectoring at other power levels...
Western machines take care of this problem automatically. I would guess some Chinese machines may do this to some extent too, but I know mine doesn't!
That all said, as you can see, I can set my 80 watt machine to where it won't cut thru paper! --barely!
-probably a bit tougher task with a 100 watt+ machine...