At this moment I haven't upped my rapids for 1 very simple reason. The machine can rapid on Y without problems at +- 1400 IPM and on X it can even go 2350 IPM.
However. Even if the machine is constructed of 35x35mm (1.4"x1.4") aluminium extrusions. When my Y axis moves fast (my acceleration is quite high on this one, at 236inches/sec²) then the whole machine is wobbling.
This is mostly because of 2 reasons:
1) The machine is still in skeleton state. When al electronics , air assist motor and fume extraction are built-in, then there will be a 2mm thick steel plating around the machine which will make the aluminium extrusions a lot more rigid and allow me to go rapids.
2) Because the machine is quite big (machine itself is 63inches long, 47 inches deep and 23.5 inches high) fast movements create a huge amount or inertia. The machine is mounted onto 2 tables and these are only standing on 4 feet.
The result is that this table is not that stable and as soon as the machine does rapids, the table begins to wobble too. (I even think that the table wobbles a lot more then the aluminium extrusions, but that is something to find out.) Once I'm ready, I'll mount plates under the table edge so that the table surface will be in full contact with the ground and not only by 4 feet. (40mm MDF plate mounted between table top and ground), you should be able to just press it underneath and it will sit there, blocking the table from wobbling.
So thats the main reason why I don't do rapids now.
The reason why you see burned edges is because I was still experimenting there with PPI settings and the cut you saw is at 100% power, 400PPI but at 35IPM. I reduced that speed to 16IPM and now the result is perfect.
The only problem I still have is rastering. The movie yousaw above is using EMC2 (not 2.5.x) with Ben Jackson config. I can get raster engraving working a little bit there, but not completely and I'm certainly not able to engrave for example 4 pictures in 1 laserjob. The laser engraves the first one, but with the next 3 it does all sweeps with X and Y axis, but nothing is burned onto wood.
So, next step is to format a machine with latest live cd and then try out your way (your config) for raster engraving.
Like I understood it now, with your system everything is in 1 single gcode file. (At least its possible).
So for example if I want to engrave a 5"x5" picture (raster engrave) and then cut it out, I could combine the engraving and cutting in 1 single .ngc file and run on linuxcnc with your config ?
That would certainly rock a lot. I don't really care if it would make the gcode file very big, thats my computers problem, not mine
So.... that'll be my next step to see how I can solve raster engraving to get consistent results without having to worry if the laser is going to shoot, or only goint to sweep but nothing shot