Dual Extruder V3 - Hobbed Shaft Gear Stripped

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kcchen_00
Posts: 1654
Joined: Thu Feb 19, 2015 12:42 am

Dual Extruder V3 - Hobbed Shaft Gear Stripped

Post by kcchen_00 » Thu Jan 03, 2019 8:13 pm

Here's an interesting one...

The big gear on my E2/T1 stripped at the hobbed shaft. The stepper still spins the big gear, but the hobbed shaft does not advance filament. Since the delrin gear is press fit onto the hobbed shaft, the metal splines defeated the plastic.

Here's a clip demonstrating the issue:
https://youtu.be/nKxiGSrCaAg

The issue looks like heat creep, clogged nozzle or starved extrusions.

Suspected root cause: Front plate of dual extruder screwed on too tight and bound hobbed shaft.

I probably re-installed the front plate too tight after disassembling to remove filament from the extruder. Once the end of the filament passes the hobbed shaft, the only options are to grip and remove with pliers/forceps or push the filament further into the extruder to make room for a new filament. Anyway, I probably screwed the long screw too far into the nylock and bound the hobbed shaft.

If you've removed the front plate of the Dual V3 to clear filament, check that the two screws aren't on too tight.



I hope this saves someone time... it was a frustrating two weeks and half a spool of troubleshooting.

ratas calientes
Posts: 1
Joined: Thu Nov 29, 2018 11:03 am

Re: Dual Extruder V3 - Hobbed Shaft Gear Stripped

Post by ratas calientes » Sun Jan 06, 2019 10:28 pm

New guy here. Thanks for the info. I am just now upgrading my TAZ 4 to a TAZ 5 with the v3 dual extruder.

One question . . . how tight is too tight? Have a torque value?

kcchen_00
Posts: 1654
Joined: Thu Feb 19, 2015 12:42 am

Re: Dual Extruder V3 - Hobbed Shaft Gear Stripped

Post by kcchen_00 » Mon Jan 07, 2019 12:31 am

No... sorry, haven't tried to figure out a torque value.

The single screw under the two longer screws is the primary for holding the plate on. The two longer screws act as an axle for the gear. The assembly instructions state to ensure the large gear moves. There are nylock nuts on the back... I've been tightening lightly then backing off a half turn.

zachah
Aleph Objects | LulzBot
Posts: 62
Joined: Mon Jul 31, 2017 9:20 am

Re: Dual Extruder V3 - Hobbed Shaft Gear Stripped

Post by zachah » Wed Jan 09, 2019 9:11 pm

If you haven't already contact us over at support about this stripped out gear.

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