How to pre-heat printing bed using G-code

[toilet-ovule-add 0]

Instead of the default glass plate i am now using a PEI coated aluminium plate instead for almost a year now.
It saves me a lot of trouble with adhesion and warping which i had when printing on glass.
There is only one small issue when initially heating the bed. The surface temperature of the bed lags behind when initially heating the bed .
Therefore printing the first layer after a cold start sometimes fails due to adhesion issues (yes i know... read on) caused by a to low temperature of the surface of the printing bed.

When i pre-heat the bed (manually) for some minutes before starting a new job resolves the issue.
So tried some Start G-code to heat the bed and wait 2 minutes before actually continue to print the first layer

 

M117 Warming up PEI Plate
M190 S{print_bed_temperature}
G4 P120000

 

For some reason the message is shown, but shortly hereafter the first layer is being printed.
Is this actually possible ? Set a display message, set the print bed temperature and wait a few minutes before starting the first layer ?

 

 

Edited March 18, 2020 by toilet-ovule-add
Change G-Code styling

[Mari 38]

... you could set the bed temperature a little bit higher...  or put a pause print command in the gcode so you have to press a button to start the initial print!

[toilet-ovule-add 0]

10 minutes ago, Mari said:

or put a pause print command in the gcode

 

And that is exactly what i tried with the gcode instruction ` G4 P120000` 

[Mari 38]

But that didn't do the trick...

 

There are 2 options in G4-command, P = time in milliseconds and S= time in seconds... For a waiting time of 2 minutes it's more logical to use S120 instead of P120000.

 

Give it a try...

 

Or use M0 command to wait untill button is pressed!

 

I have simply put some extra commands in my start Gcode to heat bed an nozzle at the same time and start when temperature is reached...

 

M140 S{material_bed_temperature_layer_0} ; start preheating the bed
M104 S{material_print_temperature_layer_0} T0 ; start preheating hotend
G28 ; home
M190 S{material_bed_temperature_layer_0} ; heat to Cura Bed setting 
M109 S{material_print_temperature_layer_0} T0 ; heat to Cura Hotend

 

 

Edited March 21, 2020 by Mari

[toilet-ovule-add 0]

The bed and hotend are already pre-heated when using Cura. The issue is that the bed needs to warm through due to the thickness of the aluminium plate.

Using the Marlin firmware documentation as a reference i tried the following by setting the initial build plate higher than the desired temperatur and then wait till the temperature of the build plate is cooled down back to the desired temperature.

 

M117 Heating up PEI Plate
M140 S80
M190 S{print_bed_temperature}

Unfortunately, the message "Heating up PEI Plate" is shown with "Press to Continue" , but then immediately starts printing.

 

 

[tinkergnome 929]

7 minutes ago, toilet-ovule-add said:

Unfortunately, the message "Heating up PEI Plate" is shown with "Press to Continue" , but then immediately starts printing.

 

What kind of printer is this and which version of Cura is used?

(and because it's not mentioned: are we even talking about Cura...?)

 

Be aware that M140 does not wait until the temperature is reached, only M190 does.

In addition: {print_bed_temperature} is deprecated (for quite some years now) and not a valid variable name for Cura anymore, the line will probably be ignored by the firmware.

 

It should be closer to your intention when you swap the sequence to:

M117 Heating up PEI Plate
M190 S80 ; wait until 80C are reached
M140 S{material_bed_temperature_layer_0} ; set to temperature from Cura - but do not wait

 

Your approach from the first post should work too if you correct the variable name.

 

[Mari 38]

What is the difference in the SET temperature and the actual temperature of the heated bed?  If the sensors is near the heating element, sensor will reach SET temperature before the complete heated bed reaches that temperature!

 

- SET a higher value... (maybe only for the first layer!)

or

- move sensor...

or

- Use something else to print in instead of a slow-heating-alu-plate...

or

- Learn to live with it... 😉

Edited March 29, 2020 by Mari

[toilet-ovule-add 0]

6 hours ago, tinkergnome said:

What kind of printer is this and which version of Cura is used?

 

Ultimaker 3, firmware 5.2.11.20190503 with Cura 4.5.0 

6 hours ago, tinkergnome said:

In addition: {print_bed_temperature} is deprecated (for quite some years now) and not a valid variable name for Cura anymore, the line will probably be ignored by the firmware.

 

Ok, i thought i had the correct documentation Marlin so probably referenced the wrong Git repo. Suggestion for a better link ?

6 hours ago, Mari said:

Use something else to print in instead

Nope, have printed on glass and find it really in-productive. Spent to many hours resolving adhesion and warping issues which all vanished after installing the PEI coated aluminium plate. 

6 hours ago, Mari said:

Learn to live with it... 😉

 

Think so, i have to deal with it 🙁. Now start a print, abort it after calibration is done and then start the job again.

 

[NotOurKing 0]

My Start G-code is

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
M300 S1318 P266
G28 Z0 ;move Z to min endstops
G0 Z0.2
G92 E0 ;zero the extruded length
G1 X40 E25 F400 ; Extrude 25mm of filament in a 4cm line. Reduce speed (F) if you have a nozzle smaller than 0.4mm!
G92 E0 ;zero the extruded length again
G1 E-1 F500 ; Retract a little
G1 X80 F4000 ; Quickly wipe away from the filament line
M117 ; Printing…
G5

 

Where would I add the preheat code to this?

[Slashee_the_Cow 619]

6 hours ago, NotOurKing said:

Where would I add the preheat code to this?

Before the G28.

[NotOurKing 0]

Awesome! Thank you