Agustin, Are you trying to vary the laser power as part of the rastering process, or simply turn the laser on and off based on some preset power level, which seems to be the case in link you reference?
In the latter case, there are some significant limitations in EMC to do this at any high rate of speed. Many of these types of engraver systems operate at speeds in excess of 50 IPS, which means even if you can get the servo period as fast as 200 micro seconds (which can be done but requires a few tricks), you will still have a maximum resolution of about 0.01" (@50 IPS) or ~0.25 mm. Well below the resolution of most of these systems. Whether you do the gating of the laser with the Z axis or a G62 / G63 code, you are going to run into the issue addressed in section 2.1.4 of the User's Guide, presuming of course that you have made Z small enough to not slow things down there as well. If you make changes over very short distances, the system is going to slow down. The only solution I have found to this problem is to adjust the laser power proportionate to the instantaneous velocity of the head. My application is not like yours however, as I am dynamically adjusting the laser power on the fly, and don't generally need to run at anything close to say 50 IPS. Regards, Eric I find a similar problem, without solution. http://www.cnczone.com/forums/showthread.php?t=93949 ----------------------- I still can not yet eliminate the delays. Connecting the Laser to the Z (A, B, C, U, V, or W) direction pin rather than the spindle does solve the problem. This delays are a headache. I just need turn the laser on and off without having these delays. ----------------------------------------------- I'm trying to do rastering with a laser. But each time the pwm changes, the movement stops for a few milliseconds. If in the next pixel changes the pwm, then there is a slight pause. Is there any way to make rastering at a constant speed, with no pauses when change the pwm?. If the g-code is: G1 X0 S 200 G1 X20 S100 G1 X25 S150 there is acceleration from X0, deceleration to X20, acceleration from X20, deceleration to X25, etc. So the speed is not constant and the laser kept more time in the positions X0, X20, X25, etc. This makes the laser burn more at those points. I think there is a constant speed mode, but I dont know how tu use it. Some people suggest to connect the laser to the Z value rather than the spindle. I don't like very much this approach. ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
