Engraving a photo, astonishing result

[Evan]

Last night I decided to try drag engraving a photograph. For the material I used some sheet copper because I wanted as much contrast as possible and copper is darker than aluminum or brass.

The photos I have seen done this way are carved using a milling cutter with the depth varied according to the gray scale level mapped to the Z axis depth. I supposed that by setting my spring loaded drag tool so that it was just barely touching the work to represent black it would produce wider and therefore brighter lines as the pressure increased because of the varying Z axis position caused by the mapping of each pixel.

To convert the photo to G-code I used a free program from the Majosoft site called BMP to DIN (G-code) available here:

http://engraving.majosoft.com/html/f...are_tools.html

It is very straightforward to use and is intended to vary the height of the cutter according to gray values, exactly what I wanted.

I encoded a picture of our Karelian Beardog and ran a few tests to see how long it would take. To speed up the process I loosened the gibs on the Z axis and unbalanced the head with some weights so I could turn off the .003 backlash compensation. Because the are no long moves during the process I raised the acceleration values as much as was safe to speed the response of the Z and X axes.

The picture is encoded at a resolution of 211 x 200 pixels resulting in 42,209 lines of G-code (!).

Putting it in action on the copper sheet all looked to be going well so I retired up stairs to work on some other items. Some time later I went to see how it was progressing and found it finished. It took 1 hour and 12 minutes to process the 42 thousand lines which was pretty good. Removing the sheet from the table I could see that there was an identifiable image present. Using some alcohol and compressed air I cleaned it and held it to the light. At first it was disappointing until I happened to hold the sheet at the correct angle.

Then, all of a sudden, the image sprang into being. It was like turning on a TV as the image began to glow brightly as if possessed of it's own source of light. I determined that all it needs is to be placed with a light source overhead somewhere and then the appearance of the image is both guaranteed and striking.

Here are some pics. I promise that these are exactly how it really appears and that I have not fiddled with the images other than to resize and combine for display.

This is how it looks. As I said, it looks like it has it's own light source. BTW, the light to the right isn't shining on the plate but behind it. That isn't the source of light.



Next is the pic at full scale beside the original, also at full scale of 211 x 200 pixels. I have grayscaled the image to match the original gray scale image on the left. It reminds me of an old black and white TV.



What is going on here is that the lighter the pixel the greater the pressure applied to the tool because of the downward movement increasing the spring force on the tool. This makes a slightly deeper and wider line in the copper which is much more reflective than the un stroked surface. Here is a closeup of the actual engraving.



I am surprised at the fidelity of the engraved image and will most certainly be doing some more experimentation.

[Your Old Dog]

Fantastic! I'd say you're mill is "ready for prime time viewing"

I can't help but think you ought to be able to make some money with your new machine.

[C - ROSS]

Evan
Everything you do is amazing, I can only wish I had your abilities.

Ross

[SGW]

That's incredible. Just don't do engraving plates for currency!

[dp]

Quite amazing, Evan. Looks like some experimenting with the tool is needed for better contrast control - there's not many grey levels, but holy cow, look at the detail caught in the tail. It's been fun watching this develop. There's probably something that can be exploited in the tapered impressions. You can see the sprung tool plunging as it moves into a lighter area. A slower movement would likely produce a round line end. It would be interesting to see what formed cutters might do with this - something that would produce an asymmetric shape. Tipping the tool head would also provide some interesting data.

[Evan]

The money comment makes me think that I could use plates like this to do art printing. I will have to try that. CNC etchings indeed.

[Guido]

Not to rob the thread, but, fellow with downtown studio has an old wooden, box camera, probably measuring 2ft x 2 ft x 2ft. Generates sepia like photos which add to his studio motif of 'old time' photos. Subjects love to dress up like Ma/Pa Kettle, etc. A thriving business for over 25 years in Solvang, Ca.

Problem is, he bought the last of the paper materials (15 month supply) available from GAF, who's no more. Kodak, etc - no more, never again, kaput.

Photographer now searching for process, chemicals, anything to duplicate the old film manufacture. To go modern, digital, 'just not in the cards'.

Evan, you're our all purpose photo man, chemical man, maintainer of historical goods and methods man, ---------any ideas?

G

[NAMPeters]

Intaglio I believe is the term. Ink the plate and get a negative image. With a little experimentation you should be able to reproduce images similar to what appear in old machine tool catalogs etc.

[snowman]

Now get yourself some liver of sulfur and steel wool.

For another interesting effect, dont cut...put a felt tipped pen in the chuck and adjust the z movement so it changes the line width of the felt. now etch like a circuit board. i can't remember if i used to do the liver treatment before or after removing the mask, but it is definately a really need feel to it. I've got a framed piece of work I did a few years ago, just four plates, arrange in a matte on a deep frame. Did it for a project in college art class, I like odd mediums.

[jacampb2]

That is awesome. The finished picture has a similar look to the older holographic images I was amazed by as a kid. Really neat, you have inspired me to finally start on my cnc router. It won't be anything near as nice as what you did, but it will be a good starter project. If you ever decide to take many more pictures of your mill, please let me know where to find them. I have already bookmarked your original thread!

Amazing work, good job!

Jason