Broken filament tension roller support

Not certain what the proper name for it is, but after only three weeks the bit that holds the bearing that pushes the filament against the feed wheel has broken, so now I can’t get any filament to feed. I feel it should have lasted longer than that! I am going to try and repair it with super glue or something for long enough that I can print a replacement part, but can someone positively identify which part it is?



That is your extruder Idler Arm. You can temporarily reattach it using Acetone, Plastic model cement, or prefferably Plastruct Plastic weld if you can find it locally. Superglue may also hold. If you call support they will probably send you a new one.

Thanks, will do that!

edit The nut spins in the part so I can’t remove the bolt - that means if I do try to put it all back together, I won’t be able to remove it after. Frustrating!


Yes, yes they do. For what it’s worth, I know your pain!

The support team have confirmed that they are sending me a new one, of a beefier design, so kudos to them for the fast response.

First job upon receipt will be to print a spare! Any other known weak points that I should know of to print off?



other things that are handy to have on hand include the small extruder gear (i’d print a couple) One large extruder gear (they usually last several years of heavy printing) and you may want to bring in the small fuses for the rambo board, one of the motor pulleys (mainly for the setscrews) a heater core and a thermistor (should be about $7 from That will cover all of the most common failure modes. Other more rarer or expensive failure modes include the PEI sheet on the bed, and potentially the extruder body itself, but those are uncommon.

Thanks, all those are in the queue for printing, and also the extruder body, which hunting through these forums has been seen to crack occasionally. The other parts I’ll pull together ofer the coming months, as you say having spare assemblies will cut down time


FOr best results, print your spare parts using the downloadable g-code, rather than the STL, and use ABS filament (I believe Lulzbot uses the Village Plastics ABS for their parts, and the g-code is reportedly optimized for that).

It is indeed village plastics abs. Push plastics abs also works there quite well. The green gears may possibly be ngen, I’ve not examined one up close to tell, just the olderight black abs ones.

If they are ngen, does that mean the gcodes are optimized for ngen as well? I’ve never printed with it, so done know what the differences might be between it and ABS

The g code would probably be optimized for the factory print. Though they nay have ran those on ghetto Taz cluster so it could be a separate consumer g code render. Not sure. Ngan is pretty close, prints a bit cooler and doesn’t need as much bed temperature

I seem to remember reading somewhere on the forums that they use ABS for the parts, with the occasional Ninjaflex washer parts. So the gcode files you are seeing are setup for printing using ABS, with the flexible ones having ‘flexy’ in the name.

I believe the gears have always been ABS (black and green).

There is mention in this 2016-1028 document that they were considering PCTPE for the gears and Cheetah for the handle, but no indication of when/if that will actually happen.

Came back to this topic a bit late, interesting to see that there were g-codes for specific materials. As soon as I got my replacement idler arm, two each of the idler arms, extruder bodies and the small extruder gear were printed using Proto-Pasta ABS.

Loking at the shapes of some of the parts, it makes me wonder if a little tweak in the designs would have made the parts stronger in key areas, but maybe there’s a good reason for the way they designed them. At least being able to make my own replacemnt parts mitigates against that