Just magic !
Doing searches on the web, I found that little python script.
It's aimed to print lampshades from grayscale images on a Makerbot.
If it works on a Makerbot it should also work on a Rapman. So let's try that...
I downloaded the script and launched it with one of the test image pattern provided.
Then I just looked at the generated G-code.
Makerbot G-code seems a bit different than the Rapman one so I can easily see this code won't work.
No need to try...
Next step is to have a look at the python script itself.
I have never done any python programming in my life so I don't even know how it's gonna look like.
Well, at least it is readable and should be easily tweaked even by a non programmer person like me. Only the beginning of the G-code is not Rapman compliant. The printed object itself (mostly G1 lines code) looks OK.
In the script that part can be easily identified and modified to have a typical Rapman sequence. You might also change the end sequence with a typical Rapman one.
Once you did that you are done. Let's try it...
Now the G-code looks fine so it's worth trying to print it.
Fail. The movements are way too slow ! Why ? That's not what the G-code says...
Having a closer look at the G1 lines I suspected that maybe there was too many floating digits for the Rapman (anyway such a precision can't be achieved).
In fact, after many trials, I found out that it is because a G-code line can't exceed 38 symbols.
Back to python I modified the script to produce G-code lines that won't exceed that lenght.
To do so I changed the G1 to only keep 2 floating digits for X and Y and 4 floating digits for Z and F. I did that choice because this script needs high precision for Z and F in order to give its best.
Z needs precision because the script can print a cylinder with continuous Z move instead of stepped layers. This is an interesting feature that produce a seamless cylinder in a spiral way (like a spring).
F needs precision because each different gray value in the bitmap will produce different feedrate (XY speed) resulting in more or less thickness in the printed cylinder (only one simple perimeter extrusion).
The results are far much better than I expected ! Amazing !
It's hard to believe that such subtile feedrate changes can produce so small details.
I printed a grayscale photo this way. At first look the printed surface looks regular and it's hard to notice anything. But when you put the object in front of some light (a window for ex.) the photo appears with very tiny details.
Just magic !
Very tiny details could be printed that way.