Modifying Start Gcode To Prime A Line?

[novice]

The ultimate goal is to prime a line across the front of the bed on the X axis of a Simple Metal prior to printing, similar to the Simple Pro routine. Looking at the Marlin Wiki causes me to realize my understanding of the change required is to put it kindly, limited. Could someone recommend modification to accomplish that?

G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G29 ;Run the auto bed leveling
G1 Z10.0 F{travel_speed} ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded length again
G1 F{travel_speed}
;Put printing message on LCD screen
M117 Printing...

[Mooselake]

That's pretty much what I've done for years...

I'd suggest moving to a bit higher Z, and extrude more like 10mm instead of 3. The extra room gives you some space to grab the extrusion so it doesn't get hauled around the bed, and the extra 7mm will do a better prime. Also, the speeds in gcode are mm per minute so you might want to revisit them. Z should be able (off the top of my head, always dangerous) to do 2 or 3 mm/sec so try at least F100 (my allthread Z would do 300, the T8-8 mod 1200 mm/min), and 3mm/sec (around 200/60) seems really slow for an extruder. I'd boost that by at least a factor of 5, then experiment by increasing the speed to see how fast it'll go. Your maximum speeds are set in EEPROM, and will be limited to the configured maximum. It's likely those are quite conservative, but that's another topic.

i thought I'd posted my start gcode here in the past (it's a bit more elaborate), but either the search-fu is weak or I haven't. Unfortunately I'm not at the computer that has it.

Kirk

[RetireeJay]

[Mooselake]

Repetier-Host will preheat the bed and extruder if you don't add explicit gcode. I think Cura does the same but don't have a way to verify it handy.

[novice]

[RetireeJay]

Are you saying they preheat without your giving a manual command to heat up AND without your hitting the "PRINT" button? I doubt it. What would trigger the preheating? Surely it doesn't start preheating just because you connected.

Here's the thing: almost all slicers will embed the M109 command in the startup code automatically - unless you go to great lengths to prevent that - so "preheating" is not a function of Repetier or Cura per se (the User Interface), but it is a function of the slicer. When you hit "PRINT" then the gcode starts running, and the printer pauses when it hits the M109 command until the extruder has reached temperature.

Come on, guys, recognize that the slicer is not the same thing as the User Interface! Repetier gives you a selection of slicers; Cura gives you only its own slicer, but in either case, the slicer is really a separate piece of software that can be run independently of the User Interface part of Repetier or Cura. And it's very advantageous to do so, IMHO! I NEVER run Slic3r from within Repetier; I ALWAYS slice first and then load the gcode into Repetier. It gives me much more control over the whole process.

[Mooselake]

I meant to say that slic3r will insert the missing heater gcode commands, somehow that became mentally abbreviated to r-h and preheat. I plead haste and old-timers

[Flordonwrath]