Hi guys, I’m new here and want to say hello with a troubling problem I’ve had a for a few days now. I have a Sintron Prusa and it prints beautifully, but 2 months into printing and I’ve been met with an issue. On large prints where it is laying solid layers slowly (Solid top layer also) it does 1 or 2 solid layers and then stops extruding like the nozzle get blocks. I’ve done 5 hour prints where it doesn’t fail on smaller prints but everytime I do a large print that takes up nearly all the bed it fails and blocks the nozzle only when doing slow bottom/top layers. Infill always works fine and had never blocked. What do you guys think? Thanks in advance!
PeteD
2
It could be one of several problem. More information on the problem is needed. Is the filament being stripped by the extruder when you see this problem? (i.e. is the filament being ‘chewed out’ by the gear teeth before the filament is pushed into the hot end) Does the extruder stepper motor get hot on extended prints? Do you hear the stepper motor skipping steps or making a stressed sound?
It’s happened 2 occasions now, the first time the extruder motors was grinding away the Filiment. The second time it carried on extruding and instead of it going through the hot end it started coming out the back with one end still in the hot end.
PeteD
4
OK. That narrows it down a bit. My best guess is that you are seeing heat-creep in the heat break of your hot end. This is a common issue for cheaper hot ends on long prints. Do you know what type of hot end you have? All-metal or does it have a PTFE liner in the heat break? Also, how is it being cooled?
It’s all metal Its cooled with a small fan next to it. Mk8 extruder Do you think I need better cooling?
PeteD
6
Yeah, you need better cooling.
FYI - the Mk8 is an awesome tribute to false advertising. They claim it is all-metal, but they are referring to the stepper motor mount, not the channel from extruder to nozzle that the plastic filament ‘sees’. The Mk8 hotend is actually a reprap design that has been around for over 8 years now, consisting of a simple aluminum cooling bar, PTFE liner sheathed in a threaded steel tube, heating block, and nozzle. They attach a large heat sink and fan to the aluminum cooling bar, but that design has always been inadequate for cooling on long prints. You will also likely see the PTFE liner eventually warping and jamming on every print, not just long ones.
Thank you very much for your help. Do you have any recommendations at all for an upgrade? Thanks in advanced
PeteD
8
I really like the E3D V6 hot end, and I’ve moved all of my printers to that. Looks like someone has even created an adapter to mount an E3D V6 hot end to a MK8 extruder and posted it to thingiverse. ( Prusa i3 mount for MK8 extruder and an E3D hotend by StevenQ-NE-UK - Thingiverse ) There are other extruder schemes out there that work well with the E3D V6 and are more compact than that, though.
Perfect! Thank you very much
