Extruder endlessly unloads at the beginning of a print.

[SteveWallin]

I'm running into a problem where I begin a print and right at the point where the extruder would usually purge, it unloads instead. It seems as if I didn't switch the printer off it would spin backward infinitely. The print will not stop at this point, the only way to kill the endless unload is to power off the machine.

The only trend I seem to have noticed is that it often happens after running the load command from the touch screen when changing filament. I can't recall if this has happened exclusively after filament changes/running the load command but, it has happened about 4-5 times now.

Anyone else had this happen?

[Jetguy]

What that indicates is that the command to load filament (manual command you send by using the LCD) does not reset to G92 E0 and so, your print resumes with a gcode E length and that's why it unloads. Question is, what slicer are you using, what style of gcode extrusion (absolute, or relative) and what update is your raise 3D front panel on??

[Jetguy]

Again, here lies a problem. If you are using absolute extrusion lengths (each line counts up in length) then if you pause or stop mid print, command some USER commands like load and unload filament, which are technically just more gcode length commands, then resume the print, there is no good recovery here.
If you g92 to 0 and the resuming segment is absolute, then on resume, it tries to extrude some massive amount of filament.
There is no way the system can reliably store the last line of gcode before manual user commands, so that's not an option to g92 "back to where you left off".

[Vicky@Raise3D]

Please check under you choose OK in loading page, will the feeding gear stops or not after a few seconds.
If it doesn't stop, please check whether it is loading or unloading.
Wait until it stops, then start print.

[SteveWallin]

What that indicates is that the command to load filament (manual command you send by using the LCD) does not reset to G92 E0 and so, your print resumes with a gcode E length and that's why it unloads. Question is, what slicer are you using, what style of gcode extrusion (absolute, or relative) and what update is your raise 3D front panel on??

I'm using Simplify 3D and the touch screen is the latest version. I'm not doing any stopping or pausing, just starting up the printer, changing the filament and beginning a new print job.

[Jetguy]

Ding ding, the bell rings. "I'm using Simplify 3D".
That means you either developed your own profile or used one, but zero guarantee that profile is correct.
As stated, your starting gcode in the printer sets up the state for the printing portion of the gcode. If certain things don't happen, then YES, totally you would see the behavior.

Either post your FFF profile so we can examine it (you may have to zip the FFF file to attach to this forum) or dropbox it.

Again, the reason here is, S3D supports ALL kinds of gcode, and will do either RELATIVE or ABSOLUTE extrusion. If you have it set incorrectly, and your starting gcode is incorrect, yes, you will unload the filament. By sending the FFF file, we get all that info in your profile and can see the problem rather than playing 50 questions.

[Jetguy]

Again, if you look at your S3D profile, under the "Scripts" tab is the start and end gcode appended to each and every print.
If that gcode does not start in the first couple of lines with a G92 E0, then again, this explains why you are seeing a massive unload command.
It's shear luck if it worked before. Again, while it's possible to cold start turn on a machine, print a file with only a G28 homing command, turn on the heaters and jump right into printing code (some Reprap based profiles start this is extremely simplified starting gcode), it leaves total luck up to the current logical machine state in memory in the controller. For reliable printing, the machine state and thus starting gcode needs to reset the coordinate system, and ensure modes and other factors are all correct before actual print gcode starts.

Here is a copy of the suggested starting gcode and ending gcode based on a known working S3D profile for the N series.
M221 T0 S100
M107
G28
G1 Z15.0 F9000.00
G92 E0
G1 E25 F200
G1 Z0 F130
G92 E0
M117 Printing.
M1001

And here is the matching ending gcode to properly park the machine in a safe state at the end of a print.
M1002
M104 S0 T1
M104 S0 T0
M140 S0
M107
M117 Print Complete.
G28 X0 Y0
G91
G1 Z10
G90
M84

[SteveWallin]

Thank you for all the info, I appreciate it. I just used the S3D profile that was available in the setup wizard in S3D and added a couple lines of code. Iv'e attached the FFF profile.

SW - Raise3D N2 Plus Single.fff.zip

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