I have been wanting to do some more front lit lithos using the bronze colored cast acrylic. Since my wife's birthday was approaching I thought I would make her a gift (but got ill and did not get it finished in time.) Anyhow, this time I tried using different bits and different quality settings to see how they effected the final product. All three test carvings were done with the same exact file.
I used a picture of my wife when she was a little girl, I had touched this up years ago as it had a rips and other defects. The file was about a 20MB BMP so it was of decent resolution. I first used the 1/16" bit with the 'Best' quality selected when uploading to the card. Then the same 1/16" bit with the 'Optimum' quality setting selected when uploading. The Optimum quality one took about twice as long to carve at around 1:40. The one done with the Optimum quality level did come out better, I hope that shows in the photos.
Next I used a 1/32" bit with the Optimum setting. There is no 1/32" bit setting in Designer so you have to use the 1/16" bit setting but in 'Optimum' quality the step over is finer. This combination produced the best looking output by far. The blotchy/blocky look of the ones done with the 1/16" bit was gone. For the final product I added an oval single color frame around the image in a photo editing program. Then I imported that into Pattern Editor and used the Magic Wand tool select the oval frame edge and erased the frame with the Eraser tool. This left just an oval shaped pattern.
One other 'hidden' feature of Pattern Editor is that when you import an image it distributes the data over the entire resolution range. When you edit a pattern you can wind up eliminating all the pixels that are at the extremes. When you use a pattern like this the Depth/Height settings in Designer may not give you the best results as it is setting the depth/height off the entire resolution range. When I was done editing the pattern in pattern editor I saved it as an MPW and then closed it and reloaded it before saving it to the Pattern Library.
All the pictures were taken in a small photo booth with a low end digital camera and only used front lighting. The camera settings are the same for each image.
I know others have had mixed results using a 1/32" bit for lithos. I'm not sure what makes the difference, if it is the image or the material.
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