Help! Top surface line when ironing (with z-hop). [2×Creality Hi]
1mon 4d ago by lemmy.ca/u/definitemaybe in 3dprinting from lemmy.ca
Every time I iron a print, I get a line like this, which I assume must be from nozzle drag; a dangling filament line wouldn't only be on the top surface, right? And, to touch, it's completely flat—no extra material is there that I can tell. It feels very slightly lower.
I have tested on my Creality Hi and my friend’s Creality Hi. My friend’s Hi seems to work better with 0.97 flow rate, vs. mine at default 0.98, so the ironing calibration is different, but the drag line is almost identical. (It moves up or down by ~1-2mm between tests, but it's the same angle and length across the same squares.)
Calibration is completed before printing.
I initially thought this looked like wiping, but I disabled wipe while retracting to off (with z-hop of 0.4mm) and this still happens. In retrospect, that makes sense, since wipe while retracting should be like 2mm, not across an entire print like this.
I then did some Googling and people online were suggesting bumping z-hop from off or 0.2mm to 0.4mm or even 0.55mm; I had 0.4mm already (the default setting), but I bumped it to 0.6mm (pictured above) and the drag line is identical. (Note that I forgot to take a picture before popping it off the plate, so please ignore the gap on the left. It was well adhered.)
Others also mentioned dragging from over extrusion; this is a crazy thin print, too, so there's no way over extrusion would be causing z-level imprecision this close. And with my friend’s Hi at 0.97 flow rate, it’s slightly under-extruded, if anything (occasional tiny line gaps in some spots on first and top layers, but better than the fused joints I was getting previously.)
FWIW, these tests were all done with JAYO basic PLA, but I get similar lines with other filaments when I use ironing.
What am I missing? What's causing that drag line? It's driving me crazy, and my Google Fu is coming up with nothing. Any tips?
What does your end G-code look like? Since it's a single line, I think it's most likely made when the extruder moves from the last ironing move to the park position
Yeah, specifically the end g-code your slicer adds by default. I bet it doesn't lift before parking. And no other slicer settings correct it since it's a fixed sequence tacked on the end.
That makes complete sense! Thank you. I think I have a fix, so including details below for future potential searchers:
The end of my g-code looks like this:
[... many copies of the below 10 lines + 2 comments with different X/Y values ...]
SET_VELOCITY_LIMIT ACCEL=3000 ACCEL_TO_DECEL=1500 SQUARE_CORNER_VELOCITY=8
G1 F11594.621
G1 X171.826 Y109.39 E.02808
G1 E-.8 F2400
;WIPE_START
G1 F11594.621
G1 X172.61 Y110.174
;WIPE_END
SET_VELOCITY_LIMIT ACCEL=6000 ACCEL_TO_DECEL=3000 SQUARE_CORNER_VELOCITY=12
G1 X184.059 Y110.251 Z1.76 F30000
G1 X190.225 Y110.293 Z1.76
G1 Z1.16
G1 E.8 F2400
;TYPE:Ironing
;WIDTH:0.403219
;HEIGHT:0.015
G1 F3000
G1 X190.225 Y91.775 E.04527
[... many G1 lines and one M73 ("print progress") line omitted ...]
; stop printing object Ironing_Test_LH0.16_medium_high id:0 copy 0
;TIME_ELAPSED:4501.019531
G1 E-.8 F2400
;WIPE_START
G1 F3000
G1 X171.925 Y93.707
;WIPE_END
EXCLUDE_OBJECT_END NAME=Ironing_Test_LH0.16_medium_high_id_0_copy_0
M106 S0
;TYPE:Custom
; filament end gcode
G1 X0 Y180 F8000
END_PRINT
M73 P100 R0
;TIME_ELAPSED:4502.550781
; EXECUTABLE_BLOCK_END
The first section shows z-hop (of 0.6mm) is enabled, as it moves to and from Z1.16 / Z1.76, and that it is doing a wipe on extract over and over again without affecting apparent print quality, as most ironing test patches look great. So, this confirms that z-hop is on (I'll revert to 0.4, the default), and that Wipe while retracting is likely safe to leave on (default setting).
The problem is the ; filament end gcode section. As we can see from the Ironing g-code, it never changes from Z1.16. This confirms that floquant@lemmy.dbzer0.com and roofuskit@lemmy.world are correct; Creality Print does not add z-hop on the last layer.
The fix, I believe, is to change the Extruder's Machine end G-code from:
G1 X0 Y180 F8000
END_PRINT
to: (comments unnecessary, of course)
G91 ; Relative movement mode
G1 Z2 F600 ; Lift nozzle 2mm
; Note: F600 is the speed I copied from the default Hi Machine start G-code: G1 Z1 F600
G90 ; Absolute movement mode
G1 X0 Y180 F8000 ; Park head
END_PRINT ; Run END_PRINT macro (heater/motor cleanup)
Thanks for your help!
Exactly right! Glad you figured it out :)
Before long you'll be tweaking your start routine to absolute perfection ;)
A word of general caution: be very careful with G90/G91, the oopsie of "I thought there was a G91 before this G1 Z-2 and now I have a little crater in my plate" is not a fun one to have, ask me how I know. I'm not saying you should try to avoid them as you would be limiting your routines a lot, but for example I like to add an empty line before every G90 and G91 block to "highlight" it