Black Granite engraving

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Black Granite engraving

Postby lasersafe1 » Mon Oct 11, 2010 2:27 pm

Bought a cheap wet tile saw from Harbor Freight. Black Granite 12X12" is $3.80 from Home Depot. Also bought a cheap sandblaster gun from Harbor Freight for finishing the sides of the granite to remove saw marks.

The exercise was as much about preparing the image as it was doing the engraving. The image is actually four images that were layered and graded in intensity to give the effect I wanted. Not too bad. I think I can do a little better though. The hardest part is learning what the minimum and maximum shading levels will look like in the final output.

Images: Google images
Software: Adobe Photoshop Elements and Corel Draw 12.
Controller: LightObjects DSP, DC 40W laser

Subject matter is a 1912 Photo of Albert Einstein. Behind the portrait is his original text from his notebook describing the general theory of relativity. On the lower portion of the image we see some other notebook scribblings and the english text translation of his theory.

35W laser at 40% power 400mm/sec
IMAG0009.jpg
IMAG0010.jpg
IMAG0011.jpg
Attachments
EINSTEIN..jpg
Dithered image at 300dpi
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Re: Black Granite engraving

Postby Tweakie » Tue Oct 12, 2010 6:21 am

Very nice indeed.

Tweakie.
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Re: Black Granite engraving

Postby lasersafe1 » Thu Oct 20, 2011 12:40 am

Two more engravings in black granite. 1st image is an 18" by 18" piece done as a donation for a local county project. I have heard that other commissioned ($$)projects are coming my way based on the quality of this work. My machine is an old ULS-25 rebuilt and is only designed to do 12" by 24". Luckily, the front door opens and I could slip it in right side up to do the top half, then I spun it 180 degrees and loaded the image upside down in Corel Draw. I then launched the Light Object software and lined it up do do the bottom half. You can't imagine how nervous I was to get it lined up. I only had one piece of granite this size and I only had one night to get it to them. I ended up putting masking tape over the granite for the bottom half. I did a test run with huge stepover on it to check alignment. Once I was sure it was correct, I removed the tape and set it to the proper resolution.

The second image is a 12" by 12" tile done for a friend at work. Her husband is a professional photographer and had the image already prepped for my engraving (other than the 1 bit dither). I love how it looks just like the dog is inside the granite. Almost a 3D illusion.



Both had scan speed 600mm/sec, 60% power of 35W max, 0.1mm stepover. (1st generation LightObjects controller)
Attachments
granite1.jpg
granite2.jpg
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Re: Black Granite engraving

Postby steppenshoe » Thu Oct 20, 2011 1:26 am

These types of projects are exactly why I want a laser to complement my CNC routers.

Very nice!
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Re: Black Granite engraving

Postby J45on » Thu Oct 20, 2011 6:50 pm

WOW the dog engraving is stunning :shock:
Are there any tutorials for doing this sort of engraving, I have only really cut stuff so far with my laser :oops:
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Re: Black Granite engraving

Postby soehler » Fri Oct 21, 2011 12:59 am

Beautiful !

Sergio
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Re: Black Granite engraving

Postby lasersafe1 » Fri Oct 21, 2011 2:50 am

J45on wrote:WOW the dog engraving is stunning :shock:
Are there any tutorials for doing this sort of engraving, I have only really cut stuff so far with my laser :oops:


Thank you. I have taught myself how to do it, but it is all about the artwork prep. I use CorelDraw 12, but most other paint programs have the same capability. You take the raw image and convert it to a 1 bit dithered bitmap. There are many types of dither to choose from. Some are straight screen dither, others are more random. I use the one called Floyd-Stienberg dither, and I reduce the dither intensity until I see that it is not going to fire the laser in unwanted black areas. I wrote about it quite a bit back when I was experimenting with 3D engraving of wood, but the same methods apply to granite.
http://www.buildlog.net/forum/viewtopic.php?f=6&t=36&start=10#p476

If you want to try something really cool, download this image and burn it in wood. If you click on the image and give it time to load, you can see that I have dithered it for ultra-fine engraving. This, of course, assumes you have a LightObject or similar DSP controller.
http://www.buildlog.net/forum/viewtopic.php?f=6&t=36&start=60#p1433
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Re: Black Granite engraving

Postby J45on » Fri Oct 21, 2011 8:51 pm

Thank you lasersafe1 I have a DSP and corel draw so I shall give these a go at the weekend
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Re: Black Granite engraving

Postby lasersafe1 » Tue Dec 06, 2011 2:55 am

Bought a wet diamond tile saw from HF last year. Last weekend I modified the table top to give me a wider adjustment on my guide (exactly 9"). Purchased some 18" square tiles from H. Depot. Cut them in half to give me two 9" by 18" pieces.

Next I bought these diamond grits for my grinder.

http://www.ebay.com/itm/12-1pc-4-Wet-Diamond-Marble-Granite-Polishing-Pad-Disc-/160693802288?pt=LH_DefaultDomain_0&hash=item256a18d530
The seller is very nice and will throw in a 6000 grit or two for free if you ask nicely.

Now I can make granite tiles with nice polished edges. It takes a while though, so I only do it when it counts.
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