Month: May 2017

PSA: Check your heater cartridge set screw, while HOT!

A few days ago, I almost had a fire occur.The heater cartridge was lying down on my print bed and was getting dragged around while “smoothing” the print and picking up molten plastic.Background:I’ve got two Malyan M150’s. No mods yet, other than a MOSFET on one. I’ve also taken apart the hotends to see the internals as I prepare to upgrade to an all-metal hotend.For safety, I take two precautions:I’m always home when printing.There’s a Nest smoke detector right above it.For this print, I hopped into the shower for about 10 minutes.When I came out, I could smell burning plastic… hop into the printer (office/guest) room,and I see the heater cartridge lying on the heated bed, being dragged around by the printer’s motions.Why it didn’t get worse:The print was just a few layers in, so the cartridge wasn’t sticking to large objects, it was just “smoothing” the surface of the print, while taking some plastic with it.It likely happened 1-2 minutes before I got back, as just part of the print was affected by the catridge’s smoothing effect.Diagnosis:Let it cool, took out the hotend, cleaned the heater cartridge with IPA,and tried to slip it back onto the hot end.It wouldn’t fit, the set screw was in the way (while cold)… so I loosened it, cartridge goes in, tightened it.Hmm, they say you should tighten your nozzle after it heats up, what about the heater cartridge?Put it all together, heated it back up to 210C.Let’s check the set screw again – its LOOSE! Tightened it again.Ever since, I’ve also noticed my nozzle gets upto temps a tad bit faster.Next things on my list to address:the heater cartridge JST connector gets HOT. Need to replace with crimp connectors.ensure MIN_TEMP is setup in my Marlin firmware. (It’d be sweet to use latest version, which has mesh bed leveling, but not sure if it’ll fit on the Malyan Melzi)…Setup automatic shutoff via Nest Protect -> IFTTT -> WemoSwitch -> Printer power http://ift.tt/2rnTqJR