Cura 14.03 Speed not changing

[kevin-osborn 9]

I wanted to do some speed experiments and I noticed that when I cranked up the speed in Cura, the prints still printed at the same speed.

Here's an excerpt from a 10mm cube at different speeds:

150mm/s:

 

;LAYER:79
G0 F9000 X110.60 Y116.90 Z8.20
;TYPE:WALL-INNER
G1 F1320 X110.60 Y108.10 E437.07423
G1 X119.40 Y108.10 E437.42623
G1 X119.40 Y116.90 E437.77823
G1 X110.60 Y116.90 E438.13023
G0 F9000 X110.20 Y117.30

Here's the same cube at 30mm/s

 

;LAYER:79
G0 F9000 X110.60 Y116.90 Z8.20
;TYPE:WALL-INNER
G1 F1320 X110.60 Y108.10 E437.07423
G1 X119.40 Y108.10 E437.42623
G1 X119.40 Y116.90 E437.77823
G1 X110.60 Y116.90 E438.13023
G0 F9000 X110.20 Y117.30

Going down to 5mm/s it does change. (I haven't determined at what speed it stops, but I'm suspicious of 1320, or 22mm/s)

 

;LAYER:79
G0 F9000 X110.60 Y116.90 Z8.20
;TYPE:WALL-INNER
G1 F300 X110.60 Y108.10 E437.07423
G1 X119.40 Y108.10 E437.42623
G1 X119.40 Y116.90 E437.77823
G1 X110.60 Y116.90 E438.13023
G0 F9000 X110.20 Y117.30

 

[kevin-osborn 9]

Here's the profile (150mm/s) The print speed was the only thing I changed in the above settings

 

[profile]
layer_height = 0.10
wall_thickness = 0.8
retraction_enable = True
solid_layer_thickness = 0.6
fill_density = 20
nozzle_size = 0.4
print_speed = 150
print_temperature = 220
print_temperature2 = 0
print_temperature3 = 0
print_temperature4 = 0
print_bed_temperature = 70
support = None
platform_adhesion = None
support_dual_extrusion = Both
wipe_tower = False
wipe_tower_volume = 15
ooze_shield = False
filament_diameter = 2.85
filament_diameter2 = 0
filament_diameter3 = 0
filament_diameter4 = 0
filament_flow = 100.0
retraction_speed = 40.0
retraction_amount = 4.5
retraction_dual_amount = 16.5
retraction_min_travel = 1.5
retraction_combing = True
retraction_minimal_extrusion = 0.02
retraction_hop = 0.0
bottom_thickness = 0.3
object_sink = 0.0
overlap_dual = 0.15
travel_speed = 150.0
bottom_layer_speed = 20
infill_speed = 0.0
inset0_speed = 0.0
insetx_speed = 0.0
cool_min_layer_time = 5
fan_enabled = True
skirt_line_count = 1
skirt_gap = 3.0
skirt_minimal_length = 150.0
fan_full_height = 0.5
fan_speed = 100
fan_speed_max = 100
cool_min_feedrate = 10
cool_head_lift = False
solid_top = True
solid_bottom = True
fill_overlap = 15
support_type = Grid
support_angle = 60
support_fill_rate = 15
support_xy_distance = 0.7
support_z_distance = 0.15
spiralize = False
brim_line_count = 20
raft_margin = 5
raft_line_spacing = 1.0
raft_base_thickness = 0.3
raft_base_linewidth = 0.7
raft_interface_thickness = 0.2
raft_interface_linewidth = 0.2
fix_horrible_union_all_type_a = True
fix_horrible_union_all_type_b = False
fix_horrible_use_open_bits = False
fix_horrible_extensive_stitching = False
plugin_config = 
object_center_x = -1
object_center_y = -1
[alterations]
start.gcode = ;Sliced at: {day} {date} {time}
	;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
	;Print time: {print_time}
	;Filament used: {filament_amount}m {filament_weight}g
	;Filament cost: {filament_cost}
	;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
	;M109 S{print_temperature} ;Uncomment to add your own temperature line
	G21        ;metric values
	G90        ;absolute positioning
	M107       ;start with the fan off
	G28 X0 Y0  ;move X/Y to min endstops
	G28 Z0     ;move Z to min endstops
	G1 Z15.0 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...
end.gcode = ;End GCode
	M104 S0                     ;extruder heater off
	M140 S0                     ;heated bed heater off (if you have it)
	G91                                    ;relative positioning
	G1 E-1 F300                            ;retract the filament a bit before lifting the nozzle, to release some of the pressure
	G1 Z+0.5 E-5 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
	G28 X0 Y0                              ;move X/Y to min endstops, so the head is out of the way
	M84                         ;steppers off
	G90                         ;absolute positioning
start2.gcode = ;Sliced at: {day} {date} {time}
	;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
	;Print time: {print_time}
	;Filament used: {filament_amount}m {filament_weight}g
	;Filament cost: {filament_cost}
	;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
	;M104 S{print_temperature} ;Uncomment to add your own temperature line
	;M109 T1 S{print_temperature2} ;Uncomment to add your own temperature line
	;M109 T0 S{print_temperature} ;Uncomment to add your own temperature line
	G21        ;metric values
	G90        ;absolute positioning
	M107       ;start with the fan off
	G28 X0 Y0  ;move X/Y to min endstops
	G28 Z0     ;move Z to min endstops
	G1 Z15.0 F{travel_speed} ;move the platform down 15mm
	T1                      ;Switch to the 2nd extruder
	G92 E0                  ;zero the extruded length
	G1 F200 E10             ;extrude 10mm of feed stock
	G92 E0                  ;zero the extruded length again
	G1 F200 E-{retraction_dual_amount}
	T0                      ;Switch to the first extruder
	G92 E0                  ;zero the extruded length
	G1 F200 E10             ;extrude 10mm of feed stock
	G92 E0                  ;zero the extruded length again
	G1 F{travel_speed}
	;Put printing message on LCD screen
	M117 Printing...
end2.gcode = ;End GCode
	M104 T0 S0                     ;extruder heater off
	M104 T1 S0                     ;extruder heater off
	M140 S0                     ;heated bed heater off (if you have it)
	G91                                    ;relative positioning
	G1 E-1 F300                            ;retract the filament a bit before lifting the nozzle, to release some of the pressure
	G1 Z+0.5 E-5 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
	G28 X0 Y0                              ;move X/Y to min endstops, so the head is out of the way
	M84                         ;steppers off
	G90                         ;absolute positioning
support_start.gcode = 
support_end.gcode = 
cool_start.gcode = 
cool_end.gcode = 
replace.csv = 
switchextruder.gcode = ;Switch between the current extruder and the next extruder, when printing with multiple extruders.
	G92 E0
	G1 E-36 F5000
	G92 E0
	T{extruder}
	G1 X{new_x} Y{new_y} Z{new_z} F{travel_speed}
	G1 E36 F5000
	G92 E0

[Daid 306]

Might be the minimal layer time kicking in?

 

[kevin-osborn 9]

Hmm, good point, however I noticed it on a bigger print (cute-spocktipus) that was scaled to an inch tall.

Now when I turn minimum layer time to 0, I still get a print estimate that stays the same unless I get to really low numbers.

The Gcode isn't as consistent though, there seems to be less speed setting (G1 Fsomething) in the 150mm/s file.

 

[kevin-osborn 9]

Here's another example. In this less tiny case, the g-code is defferent, but the time estimate is approximately the same.

The Codes don't correspond exactly to the speed I set, which makes me think that Cura is inherently imposing some limit.

Printer: Ultimaker 2, minimum time per layer set to 0, all the speed modifiers are also 0 except for travel speed which is set to 150. The print speed was set to 50 and 150 respectively for this test.

Here's a scaled down (25.4mm high) cute spocktipus at 150mm/sec. Note no speed setting on this layer. It was last set just before Layer 4 to G1 F7020, which I believe works out to 117mm/sec. On Layer 3, the speed is set on every line that extrusion takes place.

;LAYER:20

G0 X118.72 Y120.94 Z2.30

;TYPE:WALL-INNER

G1 X118.61 Y120.90 E747.54237

G1 X118.56 Y120.89 E747.54455

G1 X118.51 Y120.87 E747.54674

In the 50mm/sec example the speed is set to 50mm/sec on the first extrusion line of the layer:

;LAYER:20

G0 F9000 X118.72 Y120.94 Z2.30

;TYPE:WALL-INNER

G1 F3000 X118.61 Y120.90 E747.54237

G1 X118.56 Y120.89 E747.54455

G1 X118.51 Y120.87 E747.54674

G1 X118.44 Y120.86 E747.54928

[gr5 2,172]

Here's a scaled down (25.4mm high) cute spocktipus at 150mm/sec. Note no speed setting on this layer. It was last set just before Layer 4 to G1 F7020, which I believe works out to 117mm/sec.

It's starting to sound like you found a bug maybe. But be aware that the bottom most layer speed you have set to 20mm/sec and Cura doesn't just jump immediately to the nominal speed on the next layer but goes up a little more gradually. Maybe over 3 layers?

Also be aware that for short movements - say less than 10mm, it is unlikely that the X and Y axes even get up to full speed due to acceleration and jerk settings. So Cura's time estimate might (correctly) not change much at all even if the nominal speed is much higher.

I assume you are in ultigcode mode, but in reprap mode, the retraction speed is specified with the F (feedrate) command and you can't have different feedrates for different axes so in reprap mode Cua has to insert the nominal feedrate after every retraction. In ultigcode mode it doesn't have to but perhaps it does anyway. That might be why on some layers you seem to get many more F commands.

Also on every Z axis move (at the end of every layer) you might also get F commands there.