Hi,
Been noticing this issue during prints. It can go hours without doing it though. When it does, it’s pretty bad.
Already swapped out the small gear, same issue. Large gear looks fine, no missing teeth.
Any ideas?
Thanks
How did you mesh the gears? Is the small gear set screw on the same side of the stepper motor shaft’s flat portion?
Took apart the whole extruder assembly and one of the bearings and washer were completely destroyed. Will swap them out and see what happens.
Thanks
Mind posting an image of the washer/bearings?
Thanks!
Mine started making that same noise on retraction. Would like to know what you found wrong
Found the problem with mine, the nut that holds the large hering bone gear on the extruder was too tight and causing the gear to bind. I took the motor off and I could barely turn the gear. Loosened the nut up 1/4 turn and now it’s nice and quiet.
Threw them away already sorry! but both sides of the bearing came off, so you can see the balls inside. The pieces that came of is what was causing the jam. Bought a set of these VXB 608ZZ Set of 8 Skateboard Bearing 608Z Shielded Ball Bearings: Deep Groove Ball Bearings: Amazon.com: Industrial & Scientific
Swapped out both bearings and I was good to go.
Previously I had my rambo swapped out (Thanks Brent) because my extruder mosfet went out. I’m sure this was why. Motor drawing way too much current because of the torque needed to move the gears.
Thanks
Debris can get in the gears. We now use these similar sealed bearings:
I have a similar problem with a dual flexy print head. I’m past the warranty period (bought it more than 3 months ago from a reseller, but didn’t attempt to install it until a couple weeks ago), so I’m about at the point where I’m going to take it apart and see which parts look warped/damaged/destroyed.
In my case, the gears are clicking back and forth on the flexy side, and I saw at least one case where they did the same on the ABS side. The ABS side cleared up after backing the filament out and reloading (not sure what caused it), but the flexy side jams constantly. I don’t think it’s the steppers… manually rotating the gears on the flexy side shows a lot of resistance, so I think it could be a bearing problem or similar.
Also, when the gears spin quickly (ie, during calibration tests for measuring 100mm of filament per head when it retracts and extracts from the two heads), I can tell the large herringbone gears are mounted unevenly (ie, the gears “wobble”) on both heads. This tells me that they are either mounted cock-eyed or the bolt at their axes is bent/warped.
I won’t have time until Monday to begin this process, but I’m hopeful I can find the problem and order the appropriate parts without breaking my wallet.
kshots
I posted about the large gear being out of round here https://forum.lulzbot.com/t/out-of-round-large-herringbone-extruder-gear/1905/1
I would bet you have the same issue. I have had this same problem on 2 large round gears from Lulzbot.
If you take the extruder out and turn the large gear a bit and then wiggle it and do this all over the gear you will probably find a spot where you can wiggle the large gear 1mm or more without turning the small gear. This is what is causing the clicking on retraction. I printed a new large gear myself and no more wiggle, no more clicking, better looking prints.
I’m somewhat at a loss on this one…
I took the print head apart last night, and in the process found that there was indeed increased resistance at one section of the wheel (ie, I can turn it freely for 350 degrees, but the last 10 degrees has some resistance). Being lazy, I took my old TAZ 4 print head that I haven’t used since I upgraded to a TAZ 5 print head, removed the large herringbone gear, and used it on the flexy dually. The part fit, the gears spinned freely with uniform resistance… but I noted that the flexy dually part did not fit on the TAZ 4 tool head - it jams against a screw, which prevents it from turning.
I put it all back together, crossed my fingers, recalibrated the bed, and printed… and it continued to click/jam. Apparently, that was not the only problem.
I did note that on disassembly, it took a lot of force to remove the hobbed bolt from the bearings. Upon inspection, the mounting part does not seem to be perfectly aligned to accept the bearing. I’m not sure if that is normal (to keep everything “snug”) or if this is an issue. I found in the TAZ 4 head, things were aligned so well that they just fell out when unscrewed.
This part doesn’t look like an easy to print part, either… at least not without significant support material. I’d also have to acquire the various vitamins and utilize a soldering iron to emplace them, as well as a drill (instructions are available on OHAI-KIT)… it just looks like a lot of work.
I guess I’m saying that I’m not sure I want to go down this road if I’m not sure this is the problem. Is it normal for there to be some stress on the outer bearing (furthest from the large herringbone gear), or should it just slide in? If it’s not normal, is it likely to be the cause of this kind of problem, or am I barking up the wrong tree? If it’s not the problem, I have no idea where else to look 
The extruder body, regardless of being a flexi-dualy or a regular one has an identical axle for the hobbed bolt. You should have 2 bearings alligned with one another coaxially with the hobbed bolt itself. The bolt, if not attached to the small gear on the Stepper motor, should spin freely without resistance. The bearing sockets themselves can be fairly tight as long as they do not impede the rotation of the hobbed bolt. If they are too loose that can lead to allignment issues
Either extruder body will actually print without any support. The regular extruder body doesn’t need any heat set inserts, the Flexi-dualy needs one on the tension screw side.
Check that all of your bearings are still good. it is possible you have a gummed up bearing that needs replacing. Flexible fillament is also much slower printing than ABS. you might be trying to print it too fast, with too much retraction, etc.
The socket might be slightly out of alignment (takes a lot of force to get the bearing in), but once the bearing is in the bolt appears to spin freely. I don’t know how much resistance is appropriate.
Good to know I can print that without supports. The body in question is in fact the flexystruder body, so if I have to go down this road, I’ll need to obtain a replacement insert… and find access to a proper drill press.
The bearings appear to spin freely. I’m experiencing jams on ninjaflex… but I was using the Slic3r profile for it from lulzbot, so I thought that the flow would already be defined. I’d agree that the jamming could easily be flow-related (ie, more filament goes in than what comes out). Something to experiment with…