I have a curious issue with PLA that I am hoping someone can help me with
Pics here: https://www.dropbox.com/sh/chnlr1qjc18uw6g/shtz54-KRR
Background: I initially had the same issues with printing I believe everyone has (TAZ3 is my first 3D printer) but the forum and Lulzbot staff got me over the hump and I was able to print with ABS with only the normal issues (warping/shrinkage) which was no surprise as my printing environment is often in the 65F range. After printing almost 3 spools of ABS I decided to try PLA. I printed an entire Prototype Supply (from Amazon) spool of PLA with only one issue (in the center of the spool the filament was brittle for a few meters and broke). After that I printed an entire spool of ODB glow in the dark PLA with a similar experience (no issues except for 1 section of brittle/breaking filament). After these two spools I wondered if I would ever print with ABS again unless I had a specific need for the flex found in ABS vs PLA.
That brings us to recently. I purchased a spool of Jet brand yellow PLA and had terrible luck. I assumed this was the price to pay for getting cheap filament and bought another spool of ODB PLA in orange (remember I had great luck with this brand previously) and also had terrible luck and was unable to print things (using same gcode) I had printed previously with no issues at all. I finally decided I had learned my lesson and purchased a spool of LulzBot translucent blue PLA (and a green one which is unopened for now) and was shocked to find I could not get it to print either. I dinked around with different settings (including the Lulzbot approved Slic3r settings) with no luck at all. I tried printing files I had printed flawlessly before, etc, no luck. In the link above are some pics of the failures. I checked everything I could think of, replaced a slightly worn small gear, replaced the hobbed bolt, etc with no change. I went back to IC3D ABS (the red prints) and it works great (was able to print the Octopus tablet stand using the fast settings in a touch under 7 hours!).
Note: The pictures with the 4 prints (2 blue and 2 red) are as follows from left to right:
PLA sliced with ABS settings, PLA sliced with PLA settings, ABS sliced with same ABS settings as 1, ABS same as 1 and 4
One other note: The clamp on the extruder that has the bearing in it that pinches the filament into the hobbed bolt has a slot that guides the filament down into the hole that goes to the hot end. That guide groove has been worn out (my understanding is that glow in the dark filament is quite abrasive?) towards the front of the printer resulting in more of an L shaped groove vs the normal I shape. I cannot see how this would be related but figured it is note worthy.
For now I am back to using ABS but would love to be able to use the 4 spools of PLA I have now Any thoughts or ideas based on the pics above would be greatly appreciated.