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We wanted to test the post process properties of PVA but did not want to print anything. We unloaded the ABS that was in the printer and then started loading some PVA. After the PVA was loaded we let it keep going through the loading process until it pushed all the PVA out and we had our test sample. We then stopped the loading process and started the loading process again to put the ABS back so we could continue with normal printing procedures. Now, the ABS will not load into the right side and started making a clicking/ticking noise. Our printer is a Flashforge Dreamer. What is wrong with my printer and how can I fix it?

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Run some cleaning filament through the extruder at the printing temperature of your PVA or ABS filament, whichever is greater, until the old stuff has been completely displaced. Then load the new filament until the cleaning filament has been completely displaced.

This should be done every time you are switching materials, unless you don't mind disassembling the extruder and/or hotend and clean it out manually.

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  • $\begingroup$ When trying to load a cleaning filament, the filament doesn't load in and instead the machine makes a clicking sound. It resists the feeding $\endgroup$ – Russell Rowe Jun 4 '18 at 17:38
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    $\begingroup$ Sounds like your filament feed is jammed. If you can't run cleaning filament through it, be prepared to disassemble it and extract the debris manually. $\endgroup$ – buurin Jun 4 '18 at 17:44
  • $\begingroup$ @RussellRowe I think you are missing the point, you should not feed it automatically, you need to push it in by hand while pressing down the lever on the extruder or remove the Bowden tube (printer dependent). Just cut some strips of ABS and feed in manually like advised in my answer; it is key not to let the machine feed, you should do it instead. I've done this multiple times on an Ultimaker 3, you just need to bypass the feeder! $\endgroup$ – 0scar Jun 6 '18 at 6:33
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PVA is nasty filament to print (from experience). I use it in the Ultimaker 3 in a separate designed core (BB) and even with that core the filament frequently cooks up and carbonizes clogging the nozzle resulting in grinding of the filament at the feeder (it also attracts water really easy, so keep it in the bag with desiccant bags).

To clean the inside of the nozzle, a few techniques exist to remove blockage. E.g. by performing a cold pull or using the atomic method. Both techniques rely on the mechanism to insert the (cleaning) filament when it's hot and remove it quickly at a lower temperature. E.g. see here or here.

The trick is that you pull out all the goo inside the nozzle, you do that by raising the temperature and sticking some (cleaning or high temperature) filament (your ABS will do fine) to the goo. When the temperature lowers, you quickly pull and hope that some of the goo sticks to you cleaning filament. Cut of the tip and repeat until no goo or burnt particles come out and you can push the cleaning filament through the nozzle. You do not need the automatic feeding, it's all manual labor, just raise temperature through the menu and press the lever of the extruder to load the cleaning filament, lower temp and pull back after cooling a bit while pressing the extruder lever.

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  • $\begingroup$ PVA will carbonize if you look at it crossly. The cleaning filament method stands the best chance of getting all the debris out. Nylon works really well, as the temperatures are a bit higher than most common filaments. You may find references to "yanking" the filament. Don't. Use a strong steady pull with pliers, perhaps using a solid location as a fulcrum for a long-advantage lever action. $\endgroup$ – fred_dot_u Jun 5 '18 at 0:13
  • $\begingroup$ @fred_dot_u Indeed, I use strips of POM filament (close to nylon), works really well! $\endgroup$ – 0scar Jun 5 '18 at 11:05
  • $\begingroup$ Or just accept that nozzles are cheap, and toss 'em when really mucked up. (at least the bronze ones are -- I can understand wanting to save SS nozzles) $\endgroup$ – Carl Witthoft Jun 5 '18 at 16:01
  • $\begingroup$ @CarlWitthoft Eh... I wish... the Ultimaker 3 cores cost about 100 Euros each (nozzle cannot be replaced), but indeed if you can change the brass nozzles just replace them! $\endgroup$ – 0scar Jun 5 '18 at 18:02

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