One of the things that I wanted to make was some engravings on black granite. It took me 3 trys to get something that I thought looked ok. This is how I did it. First the granite came from Homedepot and is available in single 12 inch squares. I borrowed a tile saw and cut it down to 3.5 inch squares. It is .375 inches thick. The first thing you need to do is select a nice clear picture with good contrast. I used Photoshop to sharpen the picture slightly more than normal. You want the whites and blacks to be distinct. Here is the starting picture. The picture is 300dpi.
Next you want to convertyour picture to black and white. After that, invert the picture. It will look pretty bad, but that is what will be needed for the black background.
Now for the fun part. I used a setting of 2% power and 335 for the speed. I used the default 240 that GF chose. I tried to go higher thinking that the image would get sharper but mine did not look as good. My very first attempt was with with the power around 30% and speed at 50. Don’t use those settings, because they just make a mess of the granite. The engraving time was about 13 minutes. I used masking on the granite so I could see it on the GF UI. When the engraving was finsihed I used a razor blade to scrape the remaining masking from around the edges and the gue from the engraved areas. Next I scrubbed the tile with a fingernail brush to make sure it was clean before I applied some white acrylic paint to the surface. I just used my finger to spread it over the image. wipe it off with paper towels and then repeat the paint a second time. Wipe off with paper towels again and polish with vigorus rubbing with a dry paper towel. This is my finished product. I will post the others that I did later. I had to do one of a cat for all of the cat people.
Sorry for being so long winded. Since I have my GF I look at everything differently. I now want to know the details of how things were done.