Can't extrude PETG
I've been printing some of the Covid-19 shields using PETG, it's the first time I've used PETG. The first two printed just fine but then I tried to print the 8-stack. It printed a little over half of the print then the filament stopped extruding and the bondtec gears would just "clunk", as if it couldn't push the filament through. The nozzle seemed to be clogged, almost as if the nozzle wasn't getting hot enough to properly melt the filament. I've cleaned it and tried again many times but the nozzle keeps clogging. I've tried all kinds of different heat setting but nothing seems to help, the extruder acts like its not getting hot enough. Any ideas?
RE: Can't extrude PETG
The Masks for Docs MA group is recommending against the stacked prints due to poor print quality. Try a single and verify the quality. I've found that it takes a longer combined time to print 2 full Prusa RC3 mask sets than 2 individual single sets.
I'm printing AmazonBasics/Overture PETG at the top end of the temps (250C) with no cooling and it's working well.
RE: Can't extrude PETG
@bobstro
I can't print anything now. I can't get PETG to extrude. I've tried various temps.
RE: Can't extrude PETG
Heat the nozzle up to PETG temp and try unloading the filament.
If it's stuck, open and inspect the extruder mechanism. See if there's a blob of filament below the Bontech gear that is preventing removal.
If you are unable to remove the filament, heat temps up a bit higher and try loading new filament. If filament won't feed, you may have a blockage in the PTFE tubing between the Bondtech gears and the heater block. If so, remove any loaded filament, heat to 285C, open the extruder and try inserting a 1.5mm rod (available at hobby shops. A hex wrench can be used though they're a bit short.) down through the top of the extruder, past the open Bondtech gears and into the PTFE tubing. Brace the extruder assembly with one hand to avoid any twisting and apply steady pressure straight down using the rod. With any luck, you'll be able to push the blockage out.
If you can't push the blockage out, remove the nozzle and try pushing from above with the rod again. If that fails, clear out the nozzle area as best you can (e.g. a wire brush) and use pliers to push the 1.5mm rod up through the bottom slowly, allowing it to warm up. With any luck, the blockage will soften and pop up into the extruder area.
If none of these work, you may have to tear down the hotend and likely replace the PTFE tubing.
I've got some notes on the procedure that may be helpful.
RE: Can't extrude PETG
@bobstro
I've already disassembled it and replaced the tube, heatbreak, and nozzle. It seemed to print ok for about 20 minutes after that then started doing the same thing.
RE: Can't extrude PETG
@andyhardin
Whenever I need to reassemble the hot end I wipe off the old head sink paste from the heartbreak and add a fresh coat. I only add it to the threads that go into the finned heat sink - never to any that might get into the heat block. Not sure if this is your issue but the problems caused by less efficient heat transfer to the finned heat sink can resemble what you’re describing. There are other threads on “heat creep” IIRC.
DJ