Gcode Speed Syntax
Hi, firstly I need to mention that I am stuck using an older version of Marlin and that I am aware some of these issues may be fixed in newer versions.
My main issue is regarding the placement of the F__ speed parameter on its own line with G1: "G1 F500" before the actual movement "G1 X_ Y_" line. My firmware won't recognize an "F" without a specified axis in the same line and ignores it. For example:
G1 E1 F2000G1 F500G1 X97.362 Y74.737 E1.65204G1 X101.000 Y82.093 E1.65195G1 X97.482 Y82.093 E0.79009G1 E-1.000 F2000G1 X83.327 Y82.093 F1500G1 E1.000 F2000G1 F500G1 X78.507 Y82.093 E1.08246
I want to print at F500 but it never does because the printing moves only adopt the previous valid line with F2000. I have tried slicing with the different firmware flavors but they all seem to do this. Can there be an option to place the F parameter in the first G1 line along with the axes instead of by itself?
My other request is that there be a separate option for specifying Z movement speed. Right now it seems coupled with the X/Y "Speed for non-print moves", and the only way to make it lower is to set the machine speed limits.
RE: Gcode Speed Syntax
HI. This is a user to user forum. Any official requests or bug reports need to be made at the appropriate github. For Prusa Slicer that is located here https://github.com/prusa3d/PrusaSlicer/issues. However before opening a new issue do please read the submission guidelines and also do a search of both open & closed issues. Given there are over 4400 open ones its a busy repo and cutting down on duplicates is appreciated.
You don't mention what version of Prusa Slicer you are using. Newer versions have a separate Z Travel speed for non print moves. Under Print Settings>Speed>Speed for Non Print Moves. It is a yellow setting so you must be in Advanced or Expert modes to see it.
As for the Feed speed control being ignored with your firmware that is unlikely to be changed, as you point out its a bug with your Marlin version as its valid gcode. You can always ask though 🙂
You could however use the existing post processing methods to modify your gcode after slicing to move any lines that only contain a Fxxx to the end of the line following if a feed speed doesn't already exist on that line. Look in Print Settings>Output Options. That's a Expert/red level setting btw.
RE: Gcode Speed Syntax
one idea I have in mind is to use custom post-processing script to be run after gcode is generated, such as process every line with 'Go Ffff' or 'G` Ffff` lines to be something like 'G0 X0 Ffff` or 'G` X0 Ffff` (so that it injects X 0 move assuming relative moves), and thus it could be processed by the firmware you have.
Or just replace 'G1 Xxx Yyy' with 'G1 Xxx Yyy Ffff' from the previous line which is before the G1 X Y command block
See my GitHub and printables.com for some 3d stuff that you may like.