Nextruder assembly noise - Have others encountered this?
Hello,
I have recently upgraded my MK4S to include the MMU3 (still utilizing the high-flow nozzle with the appropriate slicer profile). First two prints have been without issue, but since my last print a concerning loud noise is now coming from the Nextruder assembly (see included video for reference to the sound). Oddly enough there appears to be no impact at this time to print quality, extrusion, retraction, or jamming-related issues (new filament out of the box - PETG from Sunlu / Prusament). But, I am reluctant to ignore a sound as severe as this that may indicate an issue with the rotating assembly. I disassembled the portion of the assembly including the planetary gear set and could not find evidence of abrasion or obstruction occurring in the rotating parts. I cleaned out the parts (reapplied grease afterwards) and double-checked the assembly and torquing of screws without identifying any issue - the sound was still present. Has anyone else encountered this sound and is there a recommended place in the assembly to look next? Thank you!Video
RE:
That doesn’t sound good! Seems like you’ve already tried everything I could think of. I’d be curious to know what you figure out.
On further reflection, I remember something about a little thin flat washer that has to go somewhere in the assembly. Maybe check on that?
MK4S/MMU3
RE: Nextruder assembly noise - Have others encountered this?
Thank you for mentioning the washer on the shaft of the motor! I can confirm the washer is installed, but I will give a look more closely when I get back to investigating to see if there are any witness marks or foreign material in that area.
RE: Nextruder assembly noise - Have others encountered this?
Pardon the delay in response - had to get to the other side of the work week. Based on LarGriff's recommendation I took a closer look at the 5 x 10 x 0.1 washer between the extruder motor and the planetary gear set; reference MK4S assembly instructions chapter 5, step 6. I did find a uniform circular scratch mark on the planetary gear-facing side of the washer that appears to be due to the inner race of the planetary gear assembly. I am uncertain if this is potentially normal wear. But, it would align with the sound matching extruder operation and an area of metal to metal contact. I may have erred in setting the depth of the planetary gears with respect to the planetary gear ring (chapter 5, step 8). So, I will reassemble the extruder with extra care and attention to this step. After some printing, I'll provide an update to report any findings.
If anyone is disassembling their extruder without any issues/noises to report, I'd appreciate it if someone could confirm if the washer includes any wear like the one I have pictured. Thank you!
Photos included are:
• 5 x 10 x 0.1 washer with the surface intact facing the extruder motor (no damage).
• Same washer with opposite surface scratched facing the planetary gear set (evidence of damage potentially related to the sound).
• "Backside" of planetary gear set showing the inner race in contact with the washer (no evidence of damage).
RE: Nextruder assembly noise - Have others encountered this?
Quick follow-up... Looking at the instructions again, I am uncertain if I may have over-tightened the cover plate to the extruder. I was particularly careful to avoid over tightening - so I thought, but this build may be extra sensitive. I'll see what I turn up there, too.
RE: Nextruder assembly noise - Have others encountered this?
So, since last assembly of the Nextruder the sound has gone away. What I believe the issue may have been was the installation of the planetary gear set too far into the planetary gear ring. I suspect that there is a relatively broad length along the extruder motor shaft that the planetary gear set can be positioned without interrupting assembly. I believe the issue may have occurred at approximately steps 28/29 of the MMU3 instructions and the planetary gear set pressed the washer onto the motor enough to create the contact and sound I heard. I was particularly careful in my last assembly to ensure the two planetary gear were installed nearly flush to the surface of the planetary gear ring as pictured in the first image of Step 29 (included in this post) and not deeper. Should someone else encounter my issue I strongly suspect matching the planetary gear set to the ring as pictured will prevent what I encountered. I believe my issue is resolved, but I will include any other updates I have should the sound return or if I find it was from another source in the Nextruder.
