Unresolved Extruder Temperature Issue.

Hi guys.

I just installed a PRINTinZ bed and changed the gcode so that the autolevel ran before the extruder heated up in order to not damage the new bed. I started experiencing the issue shown in the attached image today. Could it be to do with the new code? Here is what I used:

G28 ; home all axes
G1 Z5 F5000 ; lift Z by 5mm
M565 Z-1 ; set the offset for auto-leveling mechanism
G29 ; run auto-level

; This set of code is so that it autolevels before heating so that the BuildTek surface is not damaged
G1 Z5 F5000 ; lift Z by 5mm so it doesnt rest on the BuildTek while heating.
M140 S[bed0_temperature] ; Set Bed Temperature
M190 S[bed0_temperature] ; Wait for Bed Temperature
M104 S[extruder0_temperature] T0 ; set extruder temperature .
M109 S[extruder0_temperature] T0 ; set extruder temperature and wait for temp

When previously it was just the first 4 lines.

Could this be the cause of the issue? I haven't changed anything else and I didn't see this issue come up last night although Octoprint did say the extruder was 15 degrees below what it should have been for the entire print.


Here is the error message the terminal gave:

Recv: Error:Extruder switched off. Temperature fell too much during print!
Changing monitoring state from 'Printing' to 'Error: Extruder switched off. Temperature fell too much during print!
'
Recv: Error Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
Recv: echo: cold extrusion prevented
Recv: Printer stopped due to errors. Fix the error and use M999 to restart. (Temperature is reset. Set it after restarting)
Recv: ok
Changing monitoring state from 'Error: Extruder switched off. Temperature fell too much during print!
' to 'Closed'

 

I will now try this start code to see if it makes a difference:

G28 ; home all axes
G1 Z5 F5000 ; lift Z by 5mm
M565 Z-1 ; set the offset for auto-leveling mechanism
G29 ; run auto-level

; This set of code is so that it autolevels before heating so that the BuildTek surface is not damaged
G1 Z5 F5000 ; lift Z by 5mm so it doesnt rest on the BuildTek while heating.
M140 S[0] ; Set Bed Temperature
M190 S[0] ; Wait for Bed Temperature
M104 S[195] T0 ; set extruder temperature .
M109 S[195] T0 ; set extruder temperature and wait for temp

I have inspected the thermistor and it is not damaged. Believe it or not this is the seventh thermistor I've used. The stud ones are utterly tragic performance wise and always break within 2 months for me. The adhesive separates from the stud and lets the thermistor sensor come out. This hasn't been the case with this thermistor so I don't think it's that.

 

Using the nozzle as the bed leveling probe is an issue with these plates. Doing what you are doing is one way to handle that, but when the nozzle and bed heat up remember that things expand with heat. So your ABL might be a bit off. Also, check your part cooling fan, is it blowing too much on the nozzle? That could bring the temp down. I'll see if I can find a thread that talks about using these plates. I know it has been a topic in the past. If nothing else was changed, I find it odd that the extruder temp is struggling.

Other solutions can be to use an IR height sensor for probing the bed instead of the nozzle. I am using that and love it. There are rumors on the street that @Printed Solid might start carrying them. There is a detailed thread on this under mods. Another solution would be to update to the newer Marlin firmware that @WheresWaldo is helping get ready for the Robo. It introduces Mesh Leveling that replaces ABL. It is something done once and then set so you don't have to go through a leveling routine for each print. However, the nozzle is still used to home Z for the print and that will still give you the hot touch on your plate you don't want. The final solution I have seen that could work for you is using a servo/switch probe that @donhuevo did. It pretty much just uses a mounted servo on the x carriage to lower an arm with a button switch on the end during homing and autolevel to act as the probe and then tucks it back in when done. No more nozzle touching the bed.

I think your approach will work once the heating issue is figured out. I just wanted to make you aware of some other options that might help you as well. I'll keep looking for a thread to help with the heating issue.