Last week my 3D printer melted its own wiring right in the middle of a job site demo

I was showing off a new concrete form prototype to my boss and three project managers at our San Antonio shop. The printer was about 60% done when I smelled that nasty burning plastic smell and saw smoke coming off the hotend assembly. Turns out a cheap thermistor wire had frayed against the metal frame and shorted out, which melted about 8 inches of harness before the safety cutoff kicked in. I had to cancel the demo, which was super embarrassing since I had talked up this printer for weeks. After letting everything cool down I spent two hours replacing the whole thermistor and rewiring the harness with better strain relief and a silicone sleeve. Now I'm ordering spare thermistors and wiring kits for every printer we have on site. Has anyone else had a hotend failure ruin a critical demo or deadline for them?

2 comments

2 Comments

nancy1547d ago

The thermistor wire rubbing on sharp edges is actually the most common failure point I've seen on these printers, but it's usually not the wire itself that frays first. What usually happens is the insulation wears through where it passes through the cable chain or near a zip tie that's too tight. On my Ender 3 I had a thermistor wire short out not because of a sharp edge but because I had overtightened the zip tie holding it to the frame, which eventually pinched the insulation and caused it to fail after about 100 hours of printing. The silicone sleeve fix you mentioned should help a lot, but you might also want to check the routing path for any places where the wire bundle can twist or rub. I replaced my whole hotend setup with a PTFE lined one after that incident and havent had a single issue since.

pat3608d ago

Did you check if the thermistor wire was rubbing any sharp edges before you ran the demo? A buddy of mine had almost the exact same thing happen on his CR-10S Pro, melted the whole connector block and he had to scrap a full 18-hour print for a client prototype.