Second time I've lost a print due to resume.
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I'm about to go insane with this problem.
I keep having a problem where I consistently have a shut down in the middle of a job due to a heater fault. As soon as the part cooling fan turns on my heater seems to immediately drop out and cause a heater fault. Normally this wouldn't bother me except when I resume the print my z axis homes itself first.
This causes the print to get caught on the guide rod and lose its position or break the print off the bed entirely. The latest time happened on the last layer after a 6 hour job, and I'm about to lose my damn mind here. That or completely remove the temperature excursion setting from my config.
I'd really like to stop having this happen, so hopefully someone here might be able to help me out with this. Let me know what configs I need to post and I'll do so.
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Devil's Advocate here, but have you considered improving the part cooling so it doesn't thermally tank the hot end when it kicks in?
I used to have this problem but as soon as I improved my means of directing airflow and used a silicon heater cover I could switch two 5015s on and off full power without causing a fault.
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+1 for silicon sock if you don't already have one.
As for material cooling airflow, I saw people using a glass with water to observe the direction of the airflow under the nozzle.
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Are you saying you have to kill the power completely to clear the fault and then resume the print as if after a power loss?
@thegurry said in Second time I've lost a print due to resume.:
when I resume the print my z axis homes itself first.
If that's the case, you control how the printer is homed on resume from power loss.
https://duet3d.dozuki.com/Wiki/Setting_up_to_resume_a_print_after_a_power_failure
Ideally you should try to resolve the heater faults as dmp says.
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@zapta I haven't tried the water trick, but I'll give that a shot right now.
Never really considered a silicon sock either, I'll look into that.
@Phaedrux Not exactly, I've set a basic M562 macro and then just hit resume. It doesn't usually cause an issue if it happens early enough in the print. As long as the x axis can clear the print job it's fine, resumes no problem. Once it gets to a certain height, however that's when I start running into problems.
Not going to lie, I've been using the same cooling duct for quite some time now, and I'm sure I could find a better one out there, but I think the problem lies with the airflow bouncing back off the print or heatbed up onto the nozzle.
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@thegurry said in Second time I've lost a print due to resume.:
I think the problem lies with the airflow bouncing back off the print or heatbed up onto the nozzle.
That can be part of it for sure. Another way to help reduce the problem is to run the PID tuning for the hotend with the part cooling fan on so that it's prepared for the drop in temps.
A silicone sock will help a lot. Even kapton tape and insulation wrapped around work wonders.
https://www.amazon.ca/s?k=hotend+insulation&ref=nb_sb_noss_2
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Several excellent suggestions have already been made. You can also allow a greater temperature drop before a heater fault is raised; see https://duet3d.dozuki.com/Wiki/Gcode#Section_M570_Configure_heater_fault_detection. But if the temperature drop is exceeding 15C then it will probably cause print quality issues too.
