Laser Engraving True 8bit Shades of Grey

[Jeff Woodcock]

Welcome John,

I'm glad you finally made it here. Now I won't feel like the Lone Diode Ranger.

Jeff

[Jeff Woodcock]

Here is an example of a pulsed laser diode engraving that I dithered the original image using Atkinson. The program I'm using not only is an image to gcode program, it also has editing tools built into it with several different dithering algorithms to choose from.

Since this is the type of raster photographic engraving used by everyone here, I just wanted to show that my machine is capable of this process also. I used white wash pickling stain on the Birch Ply. first.

[Mike Null]

John

Welcome to SMC.

[John Champlain]

Thank you, Mke.
John

[Jeff Woodcock]

Happy Memorial Day

[John Champlain]

Nicely done Jeff.

My new diode has shipped, so my new build should be up and running soon.

John

[Jeff Woodcock]

Thanks John,

Can't wait to see some of your laser diode engravings.

[Jeff Woodcock]

Well, since no one will post a link to an image and engrave it with there CO2 for a comparison, I will get things started. Here is the link to the photo. http://gfx.galawallpapers.net/photo/..._Palicki_0.jpg

I used analog modulation to vary the power of my laser diode and used Birch Ply. for this engraving. The size is 9.4" X 7.056" and I ran it horizontal at 50IPM with a .007" stepover. It took 3 hours 13 minutes to complete. I went back over it with a vertical pass at 60IPM with the same stepover and it took 2 hours 41 minutes. I did this in two passes to enhance the shading and detail.

Time it takes really does not matter to me when I'm creating works of CNC art!!

[John Champlain]

Jeff,
Good job, my friend. I'd give it 5 stars if the forum would let me.
John

[Lee DeRaud]

...so based on your lack of 8bit laser diode engraving knowledge track record, I would say your wrong this time too.

So print a gray scale as I suggested before and prove us wrong. The only thing you've claimed about your setup that ours may or may not be able to do is generate 256 distinct shades of gray, but so far you really haven't shown that capability.

[Scott Shepherd]

I still don't get it either. The photo looks decent, but I've seen a lot of amazing work on this forum over the years. I imagine if I spent 6 hours on a 9" x 7" piece, I could yield some of the best results possible on a CO2 laser. However, I don't have 6 hours to work on a piece that size.

I must be missing something. I get the feeling we're supposed to be looking at the most perfectly shaded pieces we've ever seen, and I see nice work, but nothing I consider to be superior to anything else I've seen or done. I've seen some of the most amazing work ever done on a laser by the High Density Optics on a Universal. With a spot size of .0002" or something like that, you'd be hard pressed to see any higher quality in engraving shades and tones, and it doesn't take 6 hours to do a 9" x 7" piece.

Maybe if I was seeing it all in person I'd understand it all better, but at this point, I just don't see the supposed superiority of the engraving. Post the image of the girl and I'm sure some here will take a stab at it.

[Jeff Woodcock]

So print a gray scale as I suggested before and prove us wrong. The only thing you've claimed about your setup that ours may or may not be able to do is generate 256 distinct shades of gray, but so far you really haven't shown that capability.

A simpler (and significantly less subjective) test would be to 'print' an 8x8 grid of 1/2" squares (4"x4" total) covering the 256 shades of gray. This will allow us to see whether those shades can actually be resolved, which I believe is the whole point of this exercise. (Hint: baltic birch is probably one of the worst choices for this test. We need something that starts out a solid uniform color, preferably black or white.)

8X8 1/2" squares does not equal 256, only 64, so how would you be able to count them anyway? I was kinda confused what you were talking about when you requested that. It just did not add up to 256 and was not even sure how to do what you were asking. However, I have lasered 16X16 squares on Birch Ply that does equal the 8bit color pallet (256 shades). I scanned it in grey scale so it will be easier to tell the shade differences. Lee, can you count all 256 shades?

Scott, I do have to admit that the last engraving I posted was not the best I have done. Just like doing any engraving, there is editing involved and I just did not get it as good as I wanted to, but I posted it anyway because it was my last piece of Birch Ply I had. Also, I normally do not do them in 2 passes, so the time would be the 3 hours 13 minutes for this size. Here are two of my better 8bit laser engravings I have done so far. I still have not seen anything here I can compare with and I have not seen any gallery in this forum where others have posted there engravings either.

[Aaron Koehl]

Pretty amazing for a piece of plywood. What is the laser diode process-- is it a home-built machine, a cheaper alternative to CO2, or what? All I can find Googling for "laser diode machine" is laser hair removal.

[Jeff Woodcock]

Thanks Aaron,

here is a video of my machine doing one of these analog modulated laser engravings. In post 13 in this thread there is a pdf file link that explains the process and components we are using.

[Rich Harman]

However, I have lasered 16X16 squares on Birch Ply that does equal the 8bit color pallet (256 shades). I scanned it in grey scale so it will be easier to tell the shade differences. Lee, can you count all 256 shades?

I think that engraving the 256 levels would be more telling if done in order from light to dark...

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