I scaled the image down to 64x82 in gimp and increased the brightness and contrast - much better than the previous over-ambitious attempt. (@Brook_Drumm it appears you can make lithophane by varying the speed of a spiral print).
That’s a really great job. Could you post a pic without the backlight? Can you see the face in it at all without light?
@Ian_Lee_Sr You can see it reasonably well if it catches the light just right. Transparent filament would probably help. I’ll probably dig some out tomorrow.
missing/deleted image from Google+
I’m really not sure whether to be proud that it came out so well or embarrassed as I think it means my printer under-extrudes when it goes faster.
I see. So, maybe not quite as cryptic as the traditional approach but still very impressive. Nice job. I wonder if the effect works over long lengths or does the extruder eventually catch up and the fading fades out?
Make sure you are not underextruding and then make a post? Someone was posting about varying speed for clearish PLA lately. I forget who. If they are not under-extruding then maybe you will get good results by varying speeds regardless of if you are underextruding or not.
Excellent technique!
This could be a wonderful way to encode data into the outer layers of a print, such as a QR code pointing the URL of the thingiverse page for the object.
@NathanielStenzel It was @Mark_Wheadon 's post that inspired me to try it. I believe he is under-extruding in the fast sections too. My printer doesn’t under-extrude normally but I believe the speed change causes pressure imbalance. (This effect is why slic3r’s autospeed feature is useful.)
@Mark_Hindess of course, the longer filament is in the heat zone, the more it breaks down chemically too.
That looks great – there’s a ghostly feel to it that matches the old source material really well – it doesn’t look like a hack, it looks like a finished product to me.
BTW I’m not under extruding on purpose. In fact I know I’m not under extruding because the extruder distances are absolute in the code I’m post processing, so if I’d messed up the extrusion when I chop the vectors into pieces there would be a mess when the GCODE I haven’t changed was executed by the printer. Interestingly I am seeing effects like under-extrusion, but exactly the same amount of filament is being extruded as in the un-processed GCODE. I’m getting thinner parts without under0-extruding. See https://plus.google.com/+MarkWheadon/posts/MLwbkrgMTeW
By the way – I will check, but I believe I am getting thinner parts when the printer is printing slowly, thicker when printing fast. And yes, I know that makes no sense.
@Mark_Wheadon is your printer direct drive , or Bowden?
I’m curious if you are seeing artifacts due to Bowden lag.
Really cool. Good job! I wish I learned to code so I could join the fun.
Brook
@Jason_McMullan It’s a bowden system – a Kossel Mini Delta. And yes, I think I may be seeing something similar to a ringing effect at the transitions.
BTW guys I was wrong – faster -> thinner, which makes more sense!