[BUG] FTM. Complete stoppage of the extruder at a random moment in time.

[yrabbit]

Did you test the latest bugfix-2.1.x code?

Yes, and the problem still exists.

Bug Description

Overall, the FTM works very well – I don't hear any squeaking from the stepper motors, and the extruder motor doesn't squeak or click either. I get excellent quality corners without lumps or under-extrusion.
But there is one problem: at some point (it could be 2 minutes or 20 minutes after printing starts, or in the latter case, an hour and a half after printing starts), the extruder stops.

Movement along the X and Y axes continues quickly and accurately along the product, but the extruder's stepper motor remains stationary.

I can see this because the large gears of the extruder protrude beyond the gearbox housing.

And it's not a clogged nozzle or a blockage due to filament hardening in the heatbreak — if I stop printing and start the same file again, everything will be fine for a while, but then it will stop completely again.

Bug Timeline

No response

Expected behavior

I expect it to print until the end.

Actual behavior

The extruder stepper motor stops at random times, sometimes after a considerable interval.

Steps to Reproduce

1. Set the FTM settings according to my configuration files.
2. Start printing something long.

Version of Marlin Firmware

FIRMWARE_NAME:Marlin bugfix-2.1.x (Dec 20 2025 20:02:37)

Printer model

voxelab aquila

Electronics

Creality 2.4.7 motherboard

LCD/Controller

DWIN (Ender 3v2 display unit)

Other add-ons

No response

Bed Leveling

UBL Bilinear mesh

Your Slicer

Prusa Slicer

Host Software

None

Don't forget to include

• A ZIP file containing your Configuration.h and Configuration_adv.h.

Additional information & file uploads

Configs:
cfgs.zip

Extruder.

Last print, no complaints, just the extruder stopping after an hour and a half.

[dbuezas]

Do you know the total extrusion length at the time of the issue?
Does it always happen in the same spot?

[yrabbit]

I think the length varies - it may stop after a small piece of the first layer, or it may print several millimetres in height :)

And it's definitely not the same spot - I print the same box lid, but it ends up in different places.

(To be honest, I've already run out of black plastic and have a whole bag of these half-printed lids, so I've switched to grey) But I still hope that FTM will print because I like how the sides and corners turn out.

[dbuezas]

Am I understanding correctly that if you restart the print without restarting the printer the extruder starts moving again?

[dbuezas]

Also, the other axes keep moving, right?

[dbuezas]

What shapers, frequencies and smoothing times do you use at runtime?

[yrabbit]

Also, the other axes keep moving, right?

Absolutely right. X and Y continue to work, and they do so accurately along the correct trajectories.

Am I understanding correctly that if you restart the print without restarting the printer the extruder starts moving again?
Yes, that's right. However, I have

//#define FTM_HOME_AND_PROBE

so it's possible that the extruder is reinitialised (FTM part) during the initial G28.

What shapers, frequencies and smoothing times do you use at runtime?

I don't change the run-time parameters; it's easier for me to reflash.

So they are the same:

X - ZVD  40Hz  0.04s
Y - ZVD  40Hz  0.04s
Z - None          0.04s
E - None          0.03s

FTM_BUFFER_SIZE             512 
FTM_FS                     1500 Hz
FTM_MIN_SHAPE_FREQ           20Hz

[yrabbit]

What are the specifications of your machine? BTT SKR v3 EZ board, correct?

I'm just thinking that it might make sense to replace the Creality 4.2.7 with it. It won't fit in the case, and I'll probably need a different display unit and there will likely be issues with BLTouch and thermistors, but I need FTM :)

[dbuezas]

Skr3 ez, correct. It has a great microcontroller, but your current board should work fine.
I can't imagine what could cause this. I wonder if the stepper driver may be defective in some way. Have you tried swapping e and z ?

[yrabbit]

Swapping them around... hmm... that won't be very easy – they're slightly different systems.

I think I can replace the stepper motor on the extruder with a spare one.

But before that, tomorrow I will try to print the same cover on the classic model - without FTM. It will take about 4 hours, we'll see. The quality will probably not be great, but that's a question of the motor.

There probably no way to get the log of commands that are sent to the motors?

[dbuezas]

Not the stepper motors, just the wiring and marlin mapping (i.e connect z to the e header and vice versa, then swap the pins in the board file)

[dbuezas]

Oh, checking standard is fine is also a good data point

[Nuck-TH]

Seems like TMC2208 strikes again. Try increasing E smoothing time.
Also what MCU board has? And how much flash firmware takes?

[dbuezas]

Ohhh, that could indeed be the case... You could also try using poly5 or poly6 with 1.5x overshoot. That can reduce the jerk demands of linear advance (which may reduce the chance of tmc2208s going crazy.

Could it be that they are overheating instead? You could make an experiment with some desktop fan pointing at the drivers.

[yrabbit]

Seems like TMC2208 strikes again. Try increasing E smoothing time. Also what MCU board has? And how much flash firmware takes?

RAM:   [=====     ]  51.9% (used 34036 bytes from 65536 bytes)
Flash: [=====     ]  48.2% (used 238720 bytes from 495616 bytes)

MCU: