Woke up this morning to my glass bed broken on the floor and a pile of fresh spaghetti… But at least I dont have to fix anything!
I need to argue against unsupervised prints. There is a lot of current going through the many devices. If you are not home and not awake, the printer should be off. This could easily turn into a fire.
If you don’t have a smoke detector in the room, get one.
@Stephanie_A THAT’S HILARIOUS! … Should I only turn on my furnace while I’m sitting next to it too?
I agree with @Mark_Rehorst , builder beware. Learn from mistakes.
Many measures are quite simple and cost effective, trip switches / fuses, smoke detectors.
Heck, you could even make it another project by making the smoke detector cut all current and blast CO2 at the printer! 
My primary concern on my unheated bed Simple is the hotend. I would have thought hotends should have a thermal fuse to provide a physical guard against thermal runaway. (I understand some firmware have logic to detect abnormal heating conditions like heat’s been on for too long to not notice a temperature rise therefore shut down)
Otherwise, I think these devices are low energy enough that as long as they aren’t nestled in a pile of paper, scrap bits and rags soaked in solvents they should be fine. looks at over at my bench Oh wait… nevermind
BTW, did you figure out root cause? Was it the binder clips slipping off due to vibration? Z axis off causing head crash?
Looks like I’m using the same X-axis upgrade as you. I have my glass bed stuck to a thin sheet of plywood with double sided tape - the plywood is screwed with lift/leveling springs to the printed brackets much like your setup.
How big is (was) your print area and do you have any issues with wobble/vibrations along the x-axis due to the inertia of all that mass?
Firmware shuts down extrusion if thermistor fails either mechanically popping out (only possible on older cartridge based Ubis- no longer for sale) or electrically stops registering proper temp and registers a lower temp that drops below extrusion temp. The upper limit of 260 c also limits runaway. I’ve heard of a half a dozen catastrophic failures where temp freezes in the safe zone between 175 and 260 and the heater sticks on to try and heat to target temp(presumably below 260)… Then you get runaway. We can’t replicate this on current models since it requires two failures- bad temp sensing in a specific range. Our firmware won’t Extruder if the thermistor isn’t plugged in or becomes unplugged either.
Another way to theretically get runaway is if the fet fails and sticks on. They are rated for 75amps! So not sure how to replicate this either. Faulty units I guess, or an intentional firmware change to remove limits or ignore thermistor readings.
Really, a super safe heating system would have redundancy. Perhaps a separate monitoring system that shuts down power… When certain temps are reached, when bot falls over, when time of print elapses, when smoke or fire is detected, etc.
Thoughts?
What would this cost to produce? Perhaps a safety system should be designed and sold. We could at least put redundant thermistors on the hotend and bed but it would require extra electronics. You could put an electronics board that averages the temp of two thermistors and sends the value to one thermistor plug on the board. A solution like this could be done with a cheap Curcuit and work with all boards as a retrofit
Brook
@Alex_Wiebe , it looks like a corner curled up and the hotend snagged on it. I’ll have to wait until I get home to finish investigation.
I doubt you have this exact same Y axis mod, since I designed it and haven’t really posted about it. It’s based on the printable 1401 Simple mods by Jon Lawrence. I flipped the Y rods to between the Z lead-screw/rods and it can only do bowden hotends. If you’d like to give it a go the source is here: https://github.com/MechanizedMedic/PBsimple_YZ_mod
@Brook_Drumm , IMO the immediate solution for making our heating loops more robust is to convert to thermocouples and use replaceable fuses for these outputs.
I was looking at your Y axis upgrade - very cool with the bowden setup.
I was however talking about your X axis and specifically wondering if the binder clips maybe weren’t as robust/secure as planned.
@Alex_Wiebe You are correct! The clips were not in good shape and I had some bogus settings after upgrading Cura. I’ve reworked them and started a new print. I’ll get to see how it turns out when I wake up in the morning.
@Matthew_Satterlee Carl is/will be working on a thermocouple that should break the current price points! We have talked at length about it. It will be an upgrade to keep our costs low. I may include it on the forthcoming “pro” model when it is ready.
Brook