A cautionary tale

Last night I left a print running. When I came to it this morning, my computer had gone to sleep, the print had stalled not far from where I left it, and there was burnt plastic under and on the print head. I woke up the computer and the print restarted, but the extruder temperature was reading 303.4C. In fact the extruder was cold. Other than the burnt plastic on the nozzle, there seems to be no damage.

I think that when the computer went to sleep, the Duet firmware blocked on trying to send the debug data to the USB port. The Duet firmware is supposed to be non-blocking throughout, however I suspect this does not extend to all the Arduino library functions that the software uses.

So if you are going to leave your printer unattended, either disable automatic sleep on the computer, or disconnect the USB port.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I had wondered about that.... thanks for the heads up.

On windows PCs you can set the power management options for the USB controller(s)

In device manager right click on USB root hub (of which there is often more than one) and select properties -> Power Management tab and make sure the box is unchecked against "Allow the computer to turn off this device to save power"

This prevents the USB from going to sleep

Regards

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Mark

Ormerod #350

Mark, I already have it set so that the USB ports don't get turned off when the computer sleeps. But I probably don't have that one set to wake up the computer.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I have come to the conclusion that I'm not happy leaving my Ormerod unattended while running, I tend to check on it every hour or so while i'm in the house, and never leave it running over night or while out of the house.

I completed my largest print so far last night 148mm high and its beautiful, print quality is spot on, no part cleaning needed, very satisfying, however it required me waiting up til 1:30am until it finished. Leaving something at a temp of 200C+ alone is just asking for trouble, even more un-nerving seeing I have 3 young kids in the house.

I wonder if there is a thermal cutout for the hot-end and bed?

Matt

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Limited Edition Red RS Ormerod 1 #144 of 200 - RRP 1.09fw
iamburnys Ormerod Upgrades Github
Follow me on ThingiVerse My Designs

Quote
iamburny
I wonder if there is a thermal cutout for the hot-end and bed?
Matt

There is a software cutout, in that if the detected temperature goes above 300C then the corresponding heater is cut off. But the firmware does not yet use the watchdog timer, so there is no guarantee that the firmware remains running. The bed temperature will reach at most about 125C with the ATX power supply.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

If the heat sensor slips out of the block (as happened with me when I cleared a dribble of plastic from the nozzle), there is nothing to tell the firmware that it is overheating. You do eventually smell it though! No, I would also never leave the Ormerod unattended, which is why I have been running it in the living room so I can watch TV while it prints. Once the filament got tangled. I was using a 1kg spool that was on a separate holder on the floor. The first I saw was the Ormerod moving across the table - being pulled by the extruder! I was able to quickly cut the filament, and got it untangled in time to feed the cut end back into the extruder without affecting the print. Had I not been in the room glancing at the printer from time to time, it would have fallen to the floor.

Another time the firmware crashed and left the heater on permanently with no movement. Again, I was alerted by the smell.

I really need to try to get it to a stage where I am happy leaving it unattended. Some of my prints have taken 6 hours, and that's a long time to be tied to the machine.