Need help printing with coextrusion silk PLA
I'm having a distressing problem with my MK4.
I have a project with a ton of big parts. I designed and tested them using cheap PLA, and now I'm trying to print the final versions using a coextrusoin silk PLA.
I purchased one spool of coextrusion silk PLA from AMOLEN, and it printed beautifully. I went through the entire spool without a problem.
I ordered two more spools and loaded the first one. Instantly, I encountered severe nozzle clogs. I cleared the clogs (requiring a bunch of cold pulls and scraping junk out of the idler gear teeth) and tried again... same result. I tried the third spool and encountered the same problem. I can't even get the filament to load consistently - the gears click, it jams at the nozzle tip, etc.
It's mystifying - all three spools are by the same vendor, purchased within the same time frame, and printing the same models using the same printer settings. The first spool succeeded; the others are disastrous failures.
I figured I'd try the same kind of coextrusion silk PLA from another vendor. And... same problem.
Any suggestions? My contingency plan is to dump the silk PLA and choose a non-silk matte PLA, but it doesn't look anywhere near as nice for this project.
RE:
After the failures you described, you should disassemble your extruder to make sure there isn't anything trapped in there that you can't reach just from the idler lever. I ran into a similar run of troubleshooting this exact issue, and ended up with 3 instances where the filament broke and pieces lodged inside the extruder, only to be found later when it gave the click of death.
The lesson I learned with silks:
Bump your temperature (230c+) and turn down your retraction.
Heat creep is the killer, compounded by the extra non-soluble additives that gunk up the nozzle if it's not entrained in the flow. Lower temperature doesn't heat everything fully, so it builds up and eventually creates enough backpressure to the extruder gears that it starts to slip, promoting the clog, and then filament breakage if it's bad enough.
Silk filaments cause a lot of problems. Sometimes they cause a buildup of residues and one simple trick to try is to alternate silk prints with regular filament hoping the residues are flushed in the process.
If you are using silk for cosmetic reasons you may do better to use plain filament and a thicker enamel paint in post-process. If for engineering or weight distribution reasons then minimising filament use and carefully aligning lay with stresses might be substituted in places.
Cheerio,