Filament out sequence of actions



  • When the Duet senses a filament out event, it generally parks itself and waits for the operator to install new filament. The nozzle heater stays powered up as does the bed heater.
    I am a bit concerned about cooking the filament if for example I started a print and it runs out of filament during the night. It could potentially sit there for 8 hours cooking what's in the hot end.
    I could of course power off the nozzle heater(s) but how do I restore them to the previous setting(s)?
    For this to happen, do I need to wait for the conditional code to mature or is this something that can be done without conditional logic?
    What I am looking for is to save current heater temperatures, shut down the heaters and when the operator hits 'resume' bring all the temperatures up to what they were when the 'pause' action was triggered and only then continue with the 'resume' script.



  • @jens55 I can't directly answer your question as I don't have filament out sensors but I would imagine that this is just how pause and resume intended for use in the event of power failure would work. Therefore I would imagine that it's currently possible and you won't have to wait for conditional gcode. My reason for replying is just to say that PLA will hydrolyse when kept at print temperature for an extended period of time, so whatever resume script you end up with, be sure to include commands to purge out the old filament before you resume printing.



  • That is exactly what I am concerned with. I just don't know how long it is reasonable for filament (let's say PLA) to sit at printing temperature before things start to clog. The default script for pause retracts the filament 4 mm and feeds 6 mm on resume so there is a tiny bit of purging happening. This is easily increased of course but it won't help much if the PLA has turned to some solid goo because it sat there for 8 hours waiting for the operator to feed more filament.



  • @jens55 It won't clog - don't worry about that. I have a mixing hot end so have a lot of experience with filaments being held at print temperatures for extended periods of time. When I said that PLA will hydrolyse, what I meant was that it becomes more and more runny. So when you do come to use it, the first few mm come out as one big horrible runny glob. The hydrolysing process starts as soon as the filament reached about 140 ddeg C (IIRC), but it'll be at least half an hour before it becomes noticeable and the longer it's held at the that temperature, the more runny it becomes.
    PET-G seems to be largely unaffected by this phenomenon and I've had that sitting at print temperature for about 7 hours without noticing anything untoward happening.


  • administrators

    @jens55 said in Filament out sequence of actions:

    When the Duet senses a filament out event, it generally parks itself and waits for the operator to install new filament. The nozzle heater stays powered up as does the bed heater.
    I am a bit concerned about cooking the filament if for example I started a print and it runs out of filament during the night. It could potentially sit there for 8 hours cooking what's in the hot end.
    I could of course power off the nozzle heater(s) but how do I restore them to the previous setting(s)?
    For this to happen, do I need to wait for the conditional code to mature or is this something that can be done without conditional logic?
    What I am looking for is to save current heater temperatures, shut down the heaters and when the operator hits 'resume' bring all the temperatures up to what they were when the 'pause' action was triggered and only then continue with the 'resume' script.

    Test it first, but I think you can do that by putting T-1 in the pause.g file and T R1 followed by M116 in resume.g.



  • Thanks, I will give it a try !


  • administrators

    To be clear, T-1 will put the tool in standby mode, so it will reduce the tool temperature to the standby temperature. You may also want to put a G10 Rxxx command before the T-1 to set the standby temperature.


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