Raster Laser Machine only using GCode

Hi everybody,

Now I am testing my laser machine. I have good results with cutting test. My problem is with raster test. I have created a program that generates the G code from vector drawings and generates G Code for raster too. It code is generated with only G0 y G1 combination to make the desired raster drawing. I thought the look ahead algorithm the machine would work smoothly, but it is not true. it really can do the raster but it is very slow. The machine decelerate in each G1 despite this in the same straight line as the previous. I need generate it with G code because is necessary that coexist GCode of cutting and raster in a only work file. I am control the power laser with pwm output of 5i25 7i78 mesa cards and a additional digital output for enable the laser. I have interpolate the output command laser with the velocity to obtain the same power in all cutting process.

How I can do the raster with GCode and my outputs?

I have reviewed other works with raster but this work with other files and don't co-exist cutting and raster. Other problem that I seen is that in the preview of AXIS they only show a white spot on the screen and not the work to be carried out. Please any person that can help me?

G0 moves are for rapid positioning not meant for cutting or laser operations , where G1 are linear interpolated moves for cutting laser etc , they both have different speeds associated .
look at max traj and max linear settings in your ini .

I would not expect G0 and G1 moves to be at the same speed . as they both serve different purposes .
I presume you are using G94 or similar to create a constant speed move .

without knowing how you are producing the gcode or your process it's difficult to pinpoint
Lasers tend to work best at a constant moving speed . and or modifying your laser powerlevel when cutting arc's and corners .

not knowing the type of machine you have it's difficult to narrow down

I am controlling the laser with spindle (S commands). But I have modified the .hal for modified power laser (interpolate with velocity) when down the velocity in the corners. It do that the cutting result is uniform. The problem is´t in cutting, the problem is in raster.

I did make a start at a dedicated rastering GUI which doesn't use G-code at all, but didn't get very far.

I can´t do a dedicate GUI to raster because the purpose is generate the GCode from a little pluggin CAM inside Corel Draw where the user can draw multiples shapes and combine cutting and raster operation and after export the GCode and files in general to LinuxCNC.

without knowing how you are producing the gcode or your process it's difficult to pinpoint

I add a little example of a GCode generated for my little pluggin of Corel Draw for do raster of three vertical parallel rectangles.


I have replaced G0 with G1 for obtain the same velocity but don´t result.

try running either of these 2 test programs , and see if the speed is any different between moves etc

i'm trying to understand your problem in detail , if we can narrow it down a little ,
I know you will not be able to cut etc , and i'm using different macros but at the moment just looking to narrow down the problem to either the conversion or linuxcnc

just take care and just run them in air so no damage etc

try running either of these 2 test programs , and see if the speed is any different between moves etc

I try it but the speed is variable in both test file.

I would be tempted to try the original code with all but the very first M3 command removed.

Can you give me a example how I can do this change?

If you want steady speed then all moves must be G1.

If I use only G1 and I control the pwm laser with G67 it don't work (the laser don't work) and the preview in Gremlin don't show the work. If I work with original Gcode and only replace S commands with G67 commands obvious with the respective changes in .hal file the machine work better ... Is slow but not very very slow.