[Gimp-user] Feature request: Epilog laser engraver/cutter support

[Håken Hveem <krbjhvee online no>]

To my knowledge GIMP does not support laser engraving machines like
Legend Helix 24 Laser.


The spesifications for Legend Helix 24 Laser:
http://www.epiloglaser.com/legend_helix.htm

There exists a backend named epilog-cups for the legend brand of
engravers/lasers, but it seems fiddly to use and no GUI or PPD files
exists to my knowledge. I think that the epilog-cups backend only works
with inkscape, but i am unsure because i dont have a Legend laser so i
cannot test it. 

At present state, the user of epilog-cups needs to set up and make a
printer for each typer of material. 

That has some advantages, but the power and resolution and speed
apparently cannot be adjusted with ease. Anyway, it should be
possible to add a suitable plugin with a GUI that can store the
settings for a type of material.  

examples:
1mm beech plywood, cutting.
Ti6Al4V (titanium,polished) engraving
etc..
etc.. 



epilog-cups is located here + some info on how to set it up:
http://www.as220.org/labs/wiki/index.php/Laser_Cutter_Technical_Info_Links
cups-epilog.c is here:
http://aaisp.net.uk/free/cups-epilog.c

The AS220 CUPS-Epilog driver converts postscript input into a .PJL file, that is sent to the Laser 
Cutter/engraver. Apparently the Epilog uses this HP printer control language!
 ( source= http://wiki.laoslaser.org/index.php/PrinterDriver#Example_code )

Epilog laser engraver

The Epilog laser engraver comes with a windows printer driver. This
works well with Corel Draw, and that is about it. There are other
windows applications, like inkscape, but these rasterise the image
before sending to the windows printer driver, so there is no way to use
them to vector cut.

information on cups-epilog follows:

The cups-epilog app is a cups backend, 
so build and link/copy to /usr/lib/cups/backend/epilog. It allows you
to print postscript to the laser and both raster and cut. It works well
with inkscape.

With this linux driver, vector cutting is recognised by any line or curve in 100% red (1.0 0.0 0.0 
setrgbcolor).

Create printers using epilog://host/Legend/options where host is the hostname or IP of the epilog engraver. 
The options are as follows. This allows you to make a printer for each different type of material.af Auto 
focus (0=no, 1=yes)
 af optimise vectors (0=no, 1=yes)
 r Resolution 75-1200
 rs Raster speed 1-100
 rp Raster power 0-100
 vs Vector speed 1-100
 vp Vector power 1-100
 ov Re-order vectors to reduce time
 vf Vector frequency 10-5000
 sc Photograph screen size in pizels, 0=threshold, +ve=line, -ve=spot, used in mono mode, default 8.
 rm Raster mode mono/grey/colour

The mono raster mode uses a line or dot screen on any grey levels or colours. This can be controlled with the 
sc parameter. The default is 8, which makes a nice fine line screen on 600dpi engraving. At 600/1200 dpi, the 
image is also lightened to allow for the size of the laser point.

The grey raster mode maps the grey level to power level. The power level is scaled to the raster power 
setting (unlike the windows driver which is always 100% in 3D mode).

In colour mode, the primary and secondary colours are processed as separate passes, using the grey level of 
the colour as a power level. The power level is scaled to the raster power setting. Note that red is 100% 
red, and non 100% green and blue, etc, so 50% red, 0% green/blue is not counted as red, but counts as "grey". 
100% red, and 50% green/blue counts as red, half power. This means you can make distinct raster areas of the 
page so that you do not waste time moving the head over blank space between them.

It seems to me that the epilog-cups does not support 3D engraving.
3D mode looks at the dots and the dot patterns in a very different way than Basic raster engraving mode, 
especially where it concerns either color, or grayscale images.

In 3D mode, instead of looking at the dots and determining where to fire the laser based on the dot spacing, 
Epilog Laser look at the dots and determine how much laserpower (wattage) to apply to each dot, and that’s 
the big difference between Basic raster engraving mode and 3D. In Basic raster engraving mode, every dot is 
fired at the same laser output (wattage). In 3D mode machine have the ability to adjust the laser output for 
every dot.

An additional aspect of 3D mode is that, unlike Basic mode, the laser
fires continuously between most dots – even if it is engraving from a
10% fill pattern to a 30% fill pattern. This is by design so there is a
gradual change in the depth of engraving when the artwork transitions
from one shade of gray to another. The only time that this is not true
is when the artwork changes from 100% black to 100% white (or visa
versa).


Any opinions ?


-- 
Håken Hveem
Hamar
Norway
PGP/GPG Key ID : 0CD02A30