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Cura 3.0 start gCode temperatures reverting to machine defaults

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The temperatures for the extruders will not properly set within the start gCode section, they do properly set once the tool change for that extruder occurs. Presently I have the hand-edit the start of each gcode to update the warmup and purge temperatures before the print starts. I run a number of materials through this machine, so I'd rather not get around it by hacking together a new custom FDM profile with hard coded sane values, as that would still ignore the slice-time temperatures I'm trying to use.

This machine profile is built from a custom FDM profile

My start gCode:


M80 ;power onT0M117 Warming...M140 S{material_bed_temperature_layer_0} ; set bed tempM191 S60M141 S75M190 S{material_bed_temperature_layer_0} ; set bed tempM104 S200 T0M104 S200 T1M211.1 S1 X1 Y1 Z0 Z1 ;Ensure endstops are enabledG91 ;relative positioningG0 Z10 F5000 ;move Z down from wherever it isG90 ;absolute positioningG28 X0; home X axesG0 X100 F12000 ; center XG28 Y0 Z0 ;home yG1 X-30 Y240 F15000 ;deploy probeM104 S{material_print_temperature} T0M104 S{material_print_temperature} T1G32 ;probe bedG0 X100 Y240 F15000 ;center xM211.1 S0 X1 ;Disable x-max endstopG1 X240 F15000 ;Store probeG0 X100 F15000 ;center xG28 Z0M211.1 S1 X1 ;enable X endstop againT1G1 X186 Y245 F12000M109 S{material_print_temperature}G92 E0G1 E10 F100 ;purgeG92 E0M104 S0T0G1 X186 Y245 F12000M109 S{material_print_temperature} ; set extruder tempG92 E0G1 E10 F100 ;purgeG92 E0G1 X220 Y235 F15000G1 X195 Y220G1 X220 Y235G1 X195 Y235G1 X220 Y220T1G1 X195 Y220 F15000G1 X215 Y235G1 X195 Y235G1 X215 Y220T0


This screenshot I believe covers what I have things set to, and where/when I think it's pulling the incorrect values



Edited by Guest

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I may be wrong, but i think that's just the way it's implemented. These placeholders are always replaced by the values from the printers definition, not by the current material settings. @newt80ns - that's why those placeholders are quite useless for your purpose. The only other possibility i know is to leave them completely out, Cura will add the temperatures at the beginning of the gcode then. If you actually need the M80 in front of it - you're lost... @nallath knows probably much more about this topic.

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These placeholders are always replaced by the values from the printers definition, not by the current material settings.

No, they are not. Or at least, the problem is more subtle.

The problem here is that the placeholders are ignorant of the concept of multiple extruders. If you have a multi-extruder machine, materials are set per extruder, and so are the setting values for these materials. Unfortunately, the placeholders - ignorant of what extruder you are referring to - take their values from a "global" set of values. But there is no "global" material, so the value falls back to what is defined for the machine.

On a single extrusion printer, the placeholders work just fine, getting the values from the material (or the sidebar, if the user has entered another value in the sidebar).

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I'm having a similar issue with 3.1. I am running a dual extruder on a custom FDM setup. I have all of my temp settings at 240 c in my material and the side column but when I output my gCode it starts off with T0 and T1 at 240 c and then as the extruders change it randomly changes the temp on the extruders. I have shown several sections of code from the same file below to show what is happening. This is a major issue because my machine uses a combined dual extruder that does not allow me to use different values for each extruder. 


;Filament used: 33.6254m
;Layer height: 0.4
;Generated with Cura_SteamEngine 3.1.0
M190 S70
M104 S240
M104 T1 S240
M109 S240
M109 T1 S240
M82 ; absolute extrusion mode
G28 ;Home
G1 Z15.0 F6000 ;Move the platform down 15mm
;Prime the extruder
G92 E0
G1 F200 E3
G92 E0
G1 F1500 E-16
G92 E0
G92 E0
M109 S240




G0 F6300 X197.954 Y110.812
M104 T1 S230
G1 F2700 X223.309 Y110.812 E502.72313



G0 F5400 X172.944 Y85.312
M104 S225
G1 F2700 X25.48 Y85.312 E399.68004
G0 F5400 X25.48 Y87.978
G1 F2700 X172.944 Y87.978 E402.45392
G1 F1200 E386.45392
G92 E0
G92 E0
M109 S240
M104 T1 S240


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