HOTEND_IDLE_TIMEOUT shuts down hot end in while printing

[svdb99]

[Marlin 2.6.1]

Hi,
I just enabled HOTEND_IDLE_TIMEOUT with the following default settings

#define HOTEND_IDLE_TIMEOUT 
#if ENABLED(HOTEND_IDLE_TIMEOUT)
  #define HOTEND_IDLE_TIMEOUT_SEC (5*60)
  #define HOTEND_IDLE_MIN_TRIGGER   170
  #define HOTEND_IDLE_NOZZLE_TARGET   0
  #define HOTEND_IDLE_BED_TARGET      0
#endif

(printing PLA at 215C)
The time it takes for the nozzle and bed to heat up plus for ABL to complete is about 3 minutes, so 2 minutes into the print the nozzle shuts down and cools, thus failing the first layers.
Disabling the feature allows me to print normally again.

(Sidewinder X1 with stock TFT + SKR 1.4 turbo + TMC2209)

[thisiskeithb]

Please download bugfix-2.0.x to test with the latest code and let us know if you're still having this issue.

[thinkyhead]

According to my reading of the code there would have to be 5 minutes elapsed between heating up the nozzle to 170 and starting the print with E motion for a timeout to be generated. As soon as any E motion occurs it cancels the timeout.

[thisiskeithb]

I use this feature on several builds, but with a 30 minute timeout.

I tried to reproduce OP's issue by dropping HOTEND_IDLE_TIMEOUT_SEC down to the default 5*60 and starting a print with a long ABL routine.

I preheat the nozzle to 160 before ABL, so I reduced HOTEND_IDLE_MIN_TRIGGER to 160 as well to ensure I was at the trigger temperature.

The only way I could get HOTEND_IDLE_TIMEOUT to kick in was by upping my ABL grid to a 7x7 (3 probes each point) which takes longer than five minutes. If I reduce the ABL grid down to 3x3 or 5x5, warmup + abl routine can be completed in under 5 minutes and HOTEND_IDLE_TIMEOUT is never called/the print will go on just fine without shutting off the heaters.

I've also run several all-day prints on my various printers (running the latest bugfix at the time) with a 30 minute timeout and none shutoff heaters prematurely.

[svdb99]

@thisiskeithb The goal of the time out is to prevent overcooking the filament in the nozzle and risking of gunking it up. So 30 mins is too long.

[boelle]

Configurations, please
Please ZIP up your Configuration.h and Configuration_adv.h files (as
requested in the Issue template) and drop them into your next reply.
We'll check them over and see if anything is amiss.

[thisiskeithb]

So 30 mins is too long.

it’s a personal preference which is why it’s customizable. Prusa uses a 30min timeout for example.

It isn’t an issue for me since it’s mainly to catch when I preheat and forget to start a print. The nozzle is only at 160, not full temp, so I don’t have issues with clogs.

[boelle]

is this a bug after all?

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