Duet mini 5+ freezes and shuts off heaters

Michael Hathaway

@deckingman Yes, would much rather be able to adjust the parameters which are sensitive to the resets. If I lower the steps per millimeter, I run the risk of under extrusion. I manufacture automotive parts which are designed around a 0.4mm nozzle. Printing with a larger diameter nozzle would require altering the parts. And I can manually extrude from a 0.4mm nozzle at far greater speeds than those while printing, without any jamming or over driving the stepper. It is only while running a print program is there an issue.

The programming is open source, but I don't know where to make such changes. Help with this would be greatly appreciated.

deckingman

@Michael-Hathaway Understood. But I wonder if you reduced the microstepping from say 16X to 8X for the extruder, if that would actually lead to a noticeable degredation in quality? Assuming you have a 3:1 geared extruder with around 400 steps per mm at 16X, then you,d still have 200 steps per mm at 8X which is still fairly fine grained control. Regardless of quality, it might be a useful exercise, just to see if it makes any difference to your problem. It might be another data point for the Duet guys, whether it helps or not. On the other hand, it might just be a waste of filament and PA6-CF isn't cheap.
If I get chance, I'll get hold of an 0.4mm nozzle and try a print on my machine using PA6-CF with that. I use two 6HCs, one as a main board and one as an expansion board driving the extruders. I've never had any problems like those that you are experiencing but I've never used a nozzle less that 0.5mm.

dc42

@Michael-Hathaway said in Duet mini 5+ freezes and shuts off heaters:

The Duet mini must have lower settings for stepper loads which are triggering the reset. I wish I could adjust these higher. They seem too sensitive to me.

The only way in which the Duet 3 Mini responds to stepper loads is if you have stall detection enabled. You can set the stall detection threshold using M915.

Increased stepper loads will cause the board to draw more current, although it's hard to see how that could cause a reset, unless it causes the power supply voltage to drop.

In case noise is somehow being transferred to the reset line, you could connect a resistor with value e.g. 1K between the reset pin on the 12864 display socket and +3.3V.

Michael Hathaway

I can confirm that stall detection is not enabled. However, it is responding to an overload. If I slow the extrusion down, it does not send a reset. But in doing so, I have under extrusion on my print.

I will try to install a 1K ohm resistor between the reset pin and +3.3V.

[edit] There is no voltage drop from the 350W or the 600W power supplies I tested.

Michael Hathaway

A friend of mine from the Modix engineering team (who is also scratching his head over this issue), suggested adding the 1HCL expansion board just for the extruder. That way I could run the extruder at 1600-2100ma and just force the filament through the 0.4mm nozzle. The board sells for $88 dollars US and seems a tad bit extreme to solve this problem.

dc42

@Michael-Hathaway I agree, the EXP1HCL board is overkill in this situation.

I still think the most likely explanation is static discharge. Have you verified with a multimeter that there is continuity between the hot end metal work and a ground terminal on the Duet? Likewise, continuity between the extruder motor body and a ground terminal on the Duet?

Did you try adding the resistor?

dc42

PS - I just checked the schematic. The microcontroller Reset signal is connected to the reset button, the 6-pin JST ZH programming connector next to it, pin 3 of the 12864_EXP3 connector, resistors R47 and R48, and capacitor C115. Are you certain that none of those components is touching anything, especially the pins of those two through-hole connectors on the underside of the board?

I am not aware of any mechanism whereby the processor can report that the last startup was due to the reset signal when it was actually caused by something else - except that static discharge can cause the processor to malfunction in numerous ways.

It's a long shot; but have you tried using driver 4 to drive the extruder motor instead of driver 3?

Michael Hathaway

@dc42
I have confirmed continuity between hotend, extruder, D frame, Duet mini ground, power supply housing, power supply ground and earth ground.

I have not tried resistor yet. I had to switch back to normal filament to fulfill an auto parts order. When complete, I will go back to testing.

"Reset signal is connected to the reset button, the 6-pin JST ZH programming connector next to it, pin 3 of the 12864_EXP3 connector, resistors R47 and R48, and capacitor C115. Are you certain that none of those components is touching anything, especially the pins of those two through-hole connectors on the underside of the board?"

Positively sure. The case is petg, the mount screws are isolated with nylon washers, the board is semi-loose, floating, not binding in anyway.

"It's a long shot; but have you tried using driver 4 to drive the extruder motor instead of driver 3?"

I can try this, however, I have the same problem across 3 different mini boards, my last one is brand new overnight shipped from Filastruder. So the issue is not related to a single board, but all of the boards I have tested.

One other thing I can try is enabling stall detection and cranking it to the maximum.

Most filaments will just grind at the extruder when there is a clog or restriction. But this particular High temperature nylon mixed with carbon fiber is solid, it doesn't grind.

I guess I could clamp down an extruder motor with vise grips and run a test print. If it resets, I will know there is some sort of stall detection set by default. I will watch for a voltage dip while doing this experiment.

Also, I want to thank you for your help with getting to the bottom of this.

Michael Hathaway

My original resets were recorded as "cause: reset button". All resets currently are "Software reset"

dc42

@Michael-Hathaway said in Duet mini 5+ freezes and shuts off heaters:

My original resets were recorded as "cause: reset button". All resets currently are "Software reset"

In that case, please run M122 after the reset and post the result here.

Do you have the USB port connected to anything? Or any other connections to other equipment that is not powered by the Duet, not counting the Ethernet cable?

Michael Hathaway

After exhausting all possible solutions, I finally clamped a stepper motor to my work table and during a print, I increased load manually to the motor. Reset thrown. I don't wish to argue about there being an overload protection, but it seems pretty clear to me. This particular filament is very stiff and hard to push down the bowden tube to the hotend. I wish I knew where to change the overload protection limits, I think a slight tweaking would be sufficient.

I replaced the 0.4mm nozzle with 0.5mm. Reduced extrusion down -25%. Increased stepper current to 1250ma. Prints successfully every time so far.

If I drive the stepper with 1700ma, I can sucessfully print through a 0.4mm nozzle. However, this is beyond the limits of the Duet mini board and will require upgrading to a daughter board or the 6HC which is what I will do when time permits.

Thank you to everyone who took the time to help me with this issue.

dc42

@Michael-Hathaway it's interesting that the resets were previously reported as reset button but they are now reported as software reset. This supports the theory that the original resets were triggered by static discharge.

I recommend that you upgrade to firmware 3.4.5. There is a known issue in earlier 3.4 versions whereby a repeated event such as a motor stall can cause an "Out of memory" software reset.