Here are 2 tool settings for basswood. Make sure to save the file with the correct post processor which has no Z axis movement.
V CARVE 9.0 LASER POWER TEST PATTERN
MUCH OF THIS SECTION IS OUT OF DATE AND I'VE FOUND BETTER WAYS TO DO THINGS. IM KEEP THIS JUST TO HAVE A RECORD OF WHAT HAS BEEN TRIED.
I had also just started to use a laser shield that went down to about .125" above the material.
the side by side tells the story well.
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.
VERSION 5 (3 piece)
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.
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.
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.
Old laser section
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.
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.
MY JTECH MOUNT BASED OFF OF THE SHANE BELL DESIGN
DESIGNS BY PHIL, LLC
PIC ENGRAVE EXPERIMENTING AND LASER FOCUS
HOW I FOCUS MY LASER
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.
these were a smaller single line gray scale test pattern thru the software with the same results.