This is a how the laser tool is set up in V carve. Your grbl should be a laser friendly version, I recommend Larry M's jtech grbl version 1.0c. Your laser mode should be on and minimum power set to 0, max to 255. So the tool is set to max power for engraving fast. Remember there is no resistance in material you are fighting, only the momentum of the spindle.
I have shades!!!! I lowered the maximum and raised the minimum in this picture, but there still should have been a graduated pattern like this before.
Here you can see the difference between the 2 types of tool paths. Notice how on the Quick Engrave tool path the leaves are blended together and the "e" and "a" are missing their islands. Also on the Pocket tool path notice how parts of the "2" are missing because of only using one pass at 45 degrees. Two are needed 90 degrees rotated to cleanly engrave everything.
Using the tool setup above, this is how I recommend engraving. First I was using quick engrave tool paths with cross hatching. It was good and dark but it would destroy detail. I figured out why. The engraving tool path overlaps the line work. It put the tool center on path. Then I was thinking about tool paths that didn't act that way.... POCKETS! A pocket tool path will keep the diameter of the tool inside the path. But a pocket tool path doesn't cross hatch in a single tool path, so 2 are needed.
This section will be dedicated to useful tips and more based around my research and discoveries from using my Jtech 2.8w laser engraver.
So, I could burn black and white engraving pictures no problem because I was burning at power level 200 out of 255 which was enough to overcome any focus issues.
This is my "cone" technique. I use this shape to give me an easy place to zero my laser. It should be done with a step V bit that has a true point like the Whiteside 1540 60 degree bit. It's only about 0.19" in diameter.
This is a file with .125" squares and individual Quick Engrave tool paths. each are at 70ipm and go up in power from left to right by 10 starting at 50 out of 255. Your grbl should be a laser friendly version, I recommend Larry M's jtech grbl version 1.0c. Your laser mode should be on and minimum power set to 0, max to 255. My focus is now down to a 0.0065" spot and these hatches were 0.01" apart I believe.
I refocused the laser and reran the test number 6. Immediately I could see an improvement. It was still a little blochy but you could see shades.
these are the settings I used in the last test pattern. I think the maximum can be raised a bit. I will try 180 next. I will also make an attachment on the back side of the shield to hook up a fume extractor to that will blow out all the fumes and smoke outside. The low side should be around 10 though.
(This pocket was only a single pass, not cross hatched)
V CARVE 9.0 LASER POWER TEST PATTERN
SECOND POCKET TOOL PATH
WARNING: DO NOT LASER CUT OR ENGRAVE VINYL
FIRST POCKET TOOL PATH
PIC ENGRAVE EXPERIMENTING AND LASER FOCUS
these were a smaller single line gray scale test pattern thru the software with the same results.
Note the NONE for Profile Pass and the positive 45 degree angle
Note the LAST for Profile Pass and the negative 45 degree angle
so I ran a gray scale test pattern thru the software and all I got was blotchy dark burns leading up to solid dark burns with not much variation.
DESIGNS BY PHIL, LLC
V CARVE LASER ENGRAVING
the side by side tells the story well.
HOW I FOCUS MY LASER
This is how I setup jobs for both laser engraving and milling on one sign. First I mill, then I laser engrave. I found that using my "cone" technique was the most accurate for positioning. this works with items that there will be waste. the zero point should be away from clamps and in the cutoff area.
SWITCHING BETWEEN LASER AND SPINDLE IN UGS
COMBINED LASER ENGRAVING AND MILLING
Make sure to ALWAYS save the file with the correct post processor which has no Z axis movement.
V CARVE LASER TOOL SETUP
THESE ARE WITH THE 2 POCKET TOOL PATHS
Then I started experimenting with Picengrave software and I could get an image, but it didn't have the depth. It was almost like it was only using about 4 dark tones. No lighter shades were showing up.