I am using RAMPs 1.4 and Marlin firmware. I have been experimenting with slic3r inserting custom gcode between layers. The gcode I insert is the following:
G1 X135 Y0 ;Move to waiting area
M104 S150 ; turn down temperature
G4 P90000 ; Wait for a minute and a half
M104 S205 ; set temperature
M109 S205 ; wait for temperature to be reached
G1 E0.50 ;extrude a small amount to make up for ooze loss.
G92 E0 ; Reset E axis to zero
Normally I remove this gcode from before layer 0, and before layer 1.
Last night I wasn't thinking and left it in. When the print started it waited for the temp to reach 210, then hit my gcode that slic3r inserted. The Print dutifully moved to X135 Y0 and waited. When the wait was over it printed layer 0. Or rather it printed ~98% of layer 0. It didn't complete the last infill movement, nor did it move to X135 Y0. It did wait 90 seconds. When it went to print layer 1 the entire layer was shifted on the Y as if the poitn where the dwell occured was x135,y0
I reproduced this 3 times, then I commented out just the G4 90000 commad between layer 0 and layer 1.
The result was layer 0 completed, the postion correctly moved to X135, y0 and then printed layer1 correctly. When Layer 2 inserted gcode was hit. The hotend correctly moved to X135 Y0 and waited 90 seconds. In fact with only the dwell between layer 0 and layer 1 commented out. The print concluded successfully.
This seems to be an issue with the buffereing on layer 0 commands, any idea why the dwell between layer 0 and Layer 1 causes issues, but the other dwell commands do not.
Also I have noticed that the G4 dwell command tends to effect the elapse timer of the print. reseting the elapse time to zero. Not always but frequently.
The attached test.gcode generates a 100mm sqare that is 1.5mm thin, with an intersecting 50mm diameter circle on one side.
