Taz 4 idler bearing not rotating freely


Finally made the jump to the lulzbot family after having my Afinia H479 printer for 2 years as beginner printer.

I just recently bought a taz 4 from I-T works and spent 2 days just overall inspecting the entire unit. Everything looks solid and I took the time to verify that all the screws were tight and belt tension was good. The issue I ran into is when I first did an extrusion test, the filament would extrude then stop then extrude and stop. This repeats multiple times. The feed gear is full of grinded up filament and I noticed that the idler bearing is not rotating freely, it takes some effort to actually rotate it. I adjusted the tension slowly to see if the bearing will rotate and it did not. it seems to be causing a friction to the filament as the feed gear is rotating causing some extrusion issue. It looks like the bearing is on that plastic piece very well and I am unable to move it. Anyone have any suggestions on how to resolve this issue?

I removed the tensioner and applied a little bit of downward force into the extruder as it was going its print calibration and it printed perfectly. now I just need to resolve this little hiccup.

I’ve had a similar problem with my TAZ5. I don’t know if this will apply to the TAZ4 idler bearing, but I hope it will.

The cause in my case was lots of small plastic fragments (I think debris from the support structures used to make the arm that holds the idler bearing) lodged in the narrow gaps around the side of the bearing and also in the curved path that the face of the bearing rotates through. They put a heavy drag on the bearing.

The fix, for me anyhow:
– Remove the tension on the bearing arm.
– Unscrew the long screw holding the bearing arm in place and remove the bearing arm.
– Clear the particles in the gaps on the sides and along the face of the bearing. Thin metal sheets cut into small strips will help.
– For clearing any particles along the curved surface that the bearing rotates close to, the only way I found to reach into there was to partly remove the bearing from its holder. On the TAZ5 the bearing axle is a tight friction fit in the printed part. To get it started coming out I pressed the bearing holder arm against a flat piece of wood, which got it started out. Then you may have room to clear any particles there. Or you can continue and remove the bearing entirely.
– When done, press the bearing back into the arm, and reassemble everything.

I only had to do that once, and in the month since then the problem hasn’t come back. Still, whenever I have the idler bearing out of the way to do a filament change, I always check to see that it’s still spinning freely.

Let us know if that helps!

Some of the older TAZ units (all 3’s, early 4’s) shipped with non sealed bearings on the extruder. Replace that bearing with a shielded 608zz bearing and you should be all set. I think they sell them in the lulzboty store but I haven’t checked recently. They should be around $5-$10 or so.

Thanks for the suggestion. I had to pretty much dismantle the entire assemble to remove the bearing. I used the corner of a table and put pressure on the bearing itself to pop it out. The bearing seems to be busted and was not rotating at all, I can only move it maybe 1/10th then it feels like something inside it is stuck. Luckily I had several spares of 608zz bearings from my last project laying around, removed the spindle/rod thing from the old bearing and installed it on the new one. now it rotates freely and the calibration printed out just great. Bed is already leveled because I used the digital dial and also I had about 2 days of doing it since I had that extruder problem. thanks again folks.