A Whole Suite of Problems

I purchased my first 3D printer, a RepRap Mendel Prusa i3 about 3-4 months ago. I had been printing with ABS with a fair amount of success for a while. I switched to PLA about a month ago. When I first did this, my print quality skyrocketed, I was getting comparatively amazing results out of my printer. However, about a week and a half after the filament switch (after some particularly heavy printing), I began having issues. The extruder started jamming. The first time this happened, it took me hours to clear the barrel, but I had the printer working by the next day. Despite this, the extruder jammed again, and again. I had about 3-4 jams in the space of a week or so. When I cleared each jam, I never saw any sign of a blockage in the nozzle, everything seemed perfectly okay. The only thing I noticed, was that each failure was accompanied by a filament leakage. It appeared that the filament was backing up and collecting at the bottom of the barrel. My conclusion was that my filament was twisted, causing issues. Unfortunately, the threads connecting the barrel of my extruder to the nozzle had been worn down during each dis-assembly, rendering the hotend useless.

I ordered replacement parts within a week of the failure, and repaired my printer yesterday. I leveled my bed and started on some test prints and everything looked okay. However, as I started on some larger parts, I noticed globules forming on the extruder that later fell onto the print. I also observed a worrying quantity of filament backing up at the end of the barrel. My new prints steadily decreased in quality, becoming stringy, with several globules causing deformities in the final print. I continued to run the printer, as I didn't have time to disassemble the extruder and check for issues. I did, however, change to a completely new filament spool. Today, after about an hour of printing, my extruder has jammed. This is a completely new extruder with a new spool of filament.

I have tried just about every fix possible. The following are the fixes that I have attempted:
- Disassembled and reassembled the Y-axis
- Tightened X and Y belts
- Greased Z threaded rods and bearings
- Changed filament spool
- Attempted to eliminate twists in the filament by rotating the spool so as to negate the twists,
- Repaired broken Y-Bed
- Re-leveled print surface and moved Z-endstop countless times

None of these fixes have worked for long enough to complete a print. The prints I want to complete should take about 2.5 hours, but the extruder is jamming about an hour in. Is there anything else I should try? I have no idea what else I can try, nothing I've done seems to work.

Printer Details
Source URL: FolgerTech Prusa i3 Kit
New Extruder: Extruder - Barrel
Bed Surface: FlashForge Build Plate

Filament
Brand: ColorFabb
Type: 1.75mm PLA
Color: Dutch Orange

First things first pictures are worth thousand words add a couple to your post to help us understand you are exact issue.

You should be hot tightening everything at print temperature to prevent leakage.

PLA has to have a very sharp transition between the cold and hotend. If the plastic is softening prematurely which sounds like what your issue is try a more powerful fan cooling the heatsink.

The print gloubules that you describe sound like PLA deformation. Try to cool the print and make sure that your offsets are correct.

If all else fails git rid of the Folger crap. Find a friend to print a tried and true wades extruder to replace it. Put a e3d or similar hotend in and forget about your troubles.

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Prusa i3 Rework - Ramps 1.4 - E3d Lite6 - Full Graphic LCD Controller

Okay, I cleared the barrel and reattached the nozzle and barrel at print temperatures, as you recommended. The PTFE tube inside the barrel came out, but I was able to reinsert it. A 100mm test extrusion showed no immediate problems. I also adjusted my Slic3r settings to keep the fan on, to ensure a stronger temperature gradient. I have also attached pictures of the extruder, hotend, and print defects.

Print Setup (Fume hood on)

You can see the filament twisting before it enters the extruder. In order to counter this, I have been rotating the filament around the top of my fume hood.

Extruder and Hotend (Before Disassembly)



Print Defects/PLA Globules

The fan on the hot end in your photo is a hot end fan, not a print cooling fan. It should be connected permanently to 12V, not controlled by slic3r.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

The plastic leakage on the nozzle is probably because the heat break and nozzle are tightened against each other. Screw the nozzle in, then unscrew to a quarter turn. Thread the heater block onto the heat break. Tighten everything down at temperature. As for the blobs a whole suite of things could be causing that. I had the same issue with my Folger tech hotend and a new E3D fixes it.

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Prusa i3 Rework - Ramps 1.4 - E3d Lite6 - Full Graphic LCD Controller

The extruder might be in need of some love too. Try clean it out and check if anything is broken.
I am only familiar with the extruder to the Folger delta printer but I have no real experience of it. Replaced it from the start.

I have a Z605 which is similar. I think that since you have an enclosure your filament may be getting to soft. Secondly, there is no better purchase than a quality hotend. I use the Prometheus V2 and it is fantastic. Anything that addresses the gaps between parts in the cool and hot zones will illiminate jams. Also, if you jam, let it cool down to about 60c and reverse motor. Usually it will pull the entire filament out right up to the nozzle hole. Good luck.