Safety first when Christmas printing!
I leave mine alone, they don’t like to be watched, my printers are kind of shy.
@Daid_Braam haha! Well, we have 3 UM1s, so unless you can point me to that document, I think it still in effect:)
UMO or UMO+ machines? For UMO, yes, don’t run those unattended.
UMO+, while there isn’t an official declaration, those are build on the same basic principles as the UM3. (Same goes for the UM2)
@Daid_Braam I think they were all UMOs, but with upgrades. I’d have to ask @Jens_Chr_Brynildsen to be sure!
@Elias_Bakken @Daid_Braam yeah. They’re all UMO’s that have been rebuilt using official UM kits to UMO+. Does that mean that they’re safe for overnight printing? I’ve seen that a loose thermocouple wire will produce incorrect temp readings without failure?
One eve something smelled bad and the hotend was 300C+ while reporting just 85C. One of the wires from the TC board down to the UMO PCB had broken. Maybe we need to update them?
Upgraded UMO’s are not on the same safetly level as UMO+. As @Jens_Chr_Brynildsen already noticed, the thermocouple can fail in a horrible way. Which is one of the reasons we replaced this with a PT100 in all future designs. So don’t run those unattended.
The bad smell is the PEEK that starts to melt. Starts to happen at around 300C.
@Daid_Braam Yeah. Is there an upgrade path to PT100 though? It would be great to support overnight prints.
Officially, no. Unofficially, you need a new electronics board, PT100, power supply, and a new print cooling fan (if yours is still 12V)
It’s a bit tricky with cable lengths, but it can fit, my home printer is upgraded like this. (Advantage of working at Ultimaker, access to prototype parts that get discarded :))
I do that all the time
Monitor remotely
@Dan_Fryling Not in a MakerSpace with 250 members and no employees. Won’t help you much to see its burning when you are 20 minutes away by train 
@Dan_Fryling occasionally I’ll peak over to see what’s going on
Mine always runs when I’m not around. I am away more than I am home so when would I get my printing done?
@Dave_VanderWekke Yeah. You need to do a lot of work to cover the cutoff on your insurance when your house burns down 
Seriously though - very few printers have that warranty that UM offers regarding unattended printing. The most common problem is a broken cable that causes a fire. Standard Marlin firmware will not protect you.
@Jens_Chr_Brynildsen First, I run a Taz and not some home-made $300 junk printer. Second, I have a very advanced Smart home. I can shut off outlets, breakers and more if needed remotely. Plus there are smoke detectors and heat detectors in every room. My office has a fire door and can remotely be locked off remotely to contain a fire if necessary.
@Dave_VanderWekke Sure? Sounds like a good setup. Other people reading your comment wouldn’t know that you’re setup like that though. I do not know the specifics of the Taz firmware and their PCB, but I would guess they have some smartness built into it 
I leave my flashforge unattended for days. I’ve done 30 plus hour prints. I feel is safer than leaving my cnc mill unattended, which i do also. If i only printed things i could sit and watch entirely, I’d never get a thing done
Nice…