Quick hack for printing Ninjaflex
Lulzbot offers the Flexystruder for both the TAZ and the Mini, which is the best way to print flexibles on any machine we've seen. But if you want to try out Ninjaflex without sinking $300 into an add-on, here's how you can do it with your regular extruder.
The problem with Ninjaflex in the standard Wade's style extruder, is that it tends to buckle and fold over on itself underneath the drive gear. The Lulzbots are actually much less prone to this than other printers, since they use 3 mm filament instead of 1.75. But unless you go very slow and have almost no backpressure, it's still an issue.
Cut off a piece of the PTFE tubing that comes with your TAZ, then cut it down to the right shape to fit between the drive gears and the hole in the extruder block. This will constrain the path of the filament and prevent it from buckling. Here's a diagram showing the basic idea.
I just used some wire cutters and an Xacto knife to get it the right shape. The piece needs to be really small. If its too long, it will prevent the idler pulley from pressing against the filament, and it won't extrude.