Fix for Squeaky Extruders, especially when printing PETG  

Re: Fix for Squeaky Extruders, especially when printing PETG

I think I need to point out that I'm not the first to have this idea - I found this page on github after I had done the modeling and installed the revised parts on my machine.

Re: Fix for Squeaky Extruders, especially when printing PETG

A very brief update since I have now had a chance to print with TPU. My first try at a Rocktapus, printed with AmazonBasics Red TPU turned out absolutely fantastic, just by using a stock flexible filament profile that I found in Slic3r PE without any further profile modification.

I tried to print at some ludicrous speed as well, about 65 mm/s by my very rough estimation (volume rate was set to 6mm^3/s to eliminate that bottleneck). Print quality obviously suffered greatly, but the extruder never jammed or spit filament out its sides.

The only issue I encountered and tip that I could give would be to not use the "Load Filament" option from the menu. The initial movement appears to be a bit too quick for flexibles - it's probably more reliable and well advised to manually (using the move E-axis menu option, and slowly turning the knob on the printer) slowly load the filament.

Thanks all, and I hope this is helpful.

Re: Fix for Squeaky Extruders, especially when printing PETG

Thank you for this! I just started running into this issue after printing an entire spool of Hatchbox white PETG. I thought my issues was with the PTFE tube rubbing on the bontech gears. So I removed the hot end and flipped the PTFE tube around since I saw that it was deformed (wasn’t a perfect circle at the opening). But the squeak came back, but not as loud. I will try printing out your updated solution and see if the issue comes back.

I will print out the stl files that you uploaded on MyMiniFactor and return with results.

I do have one question for you though. Do I just need to print out the two following sql files?

-extruderbody-n3-alignfilamentpath-v1-1-oriented
-repaired_extrudercover-n3-alignedfilamentpath-oriented

Or do I need to print out all 5 stl files?

Attached is a photo of what I saw and I thought that was the problem.

Thanks,
David

Re: Fix for Squeaky Extruders, especially when printing PETG

I do have one question for you though. Do I just need to print out the two following sql files?

-extruderbody-n3-alignfilamentpath-v1-1-oriented
-repaired_extrudercover-n3-alignedfilamentpath-oriented

You're correct, only those two are required. The original R3 print fan arm bracket thing should work fine if you have already printed it, and the new additional side bracket is also optional. There is also no physical difference between the R3 nozzle and my new fan nozzle once printed, so the original R3 nozzle should also be fine.

Thanks for your feedback!

Edit:

I flipped the PTFE tube around since I saw that it was deformed (wasn’t a perfect circle at the opening)

Yes, that's exactly what I saw, now that you reminded me. It's funny - I didn't actually connect the deformed PTFE tube with this issue (though it's certainly the cause). Thanks again!

Edit 2: also, people keep mentioning the PTFE tube rubbing against the bondtech gears causing a squeak - I don't think that it's physically possible for PTFE (Teflon) to cause a friction/rubbing squeak (think about the sound of utensils against a non-stick pan... I've never heard a teflon pan squeak). The static and dynamic coefficients of friction are the same (and relatively low) for teflon on most materials, which is why it's "slippery" - it doesn't stick to things, and it won't vibrate when rubbed against metal.

Re: Fix for Squeaky Extruders, especially when printing PETG

There was another recent update after R3 which removes a lip just after the filament sensor (More important for the MMU2 but I hate when I hit it loading filament). (Released Approx Dec 3, mentioned page 39 of this guide: https://prusa3d.com/downloads/manual/prusa3d_manual_mmu2_eng_1_03.pdf ). Does this also include that update? And any way we can get that filament path a little tighter to the idler? I have some really soft filament which I struggle with.

Re: Fix for Squeaky Extruders, especially when printing PETG

There was another recent update after R3 which removes a lip just after the filament sensor (More important for the MMU2 but I hate when I hit it loading filament). (Released Approx Dec 3

That's interesting, and is the first I've heard of this. Do you have an updated .stl or other model from Prusa? The latest files posted on Github are still dated from August, 2018 (and that date matches the files in the Prusa i3 Printable parts .zip file from the official page.

In either case, I do not see a lip anywhere in the model beneath the filament sensor, in either my model or the official R3 model. I wonder if the "extruder upgrade parts supplied with MM2 that were shipped approximately before December 3, 2018" simply means that back stock of printed parts were shipped, and kits shipped after that date contained the newer (August) version of the part. See below for a cross section comparing the R3 and N3 parts:

In the printed part, I do see the potential for a "lip" to form or something that would cause resistance in the filament due to bridging across the top of the hole as the part is printed. I have added a feature that should address this, by using a "teardrop" shape for the tightest filament path section; that should move any lip out of the way. It is, however, best practice in my opinion to, after printing the new extruder body, take a 2mm drill bit (5/64") and insert it in the filament path while twisting by hand or a pair of pliers (no drill needed, really....) to ensure that the path above the gears is nice and clear.

I have some really soft filament which I struggle with.

Have you been struggling with the official R3 parts? Or have you tried my "N3" parts yet?
By "tighter", do you mean "lower", as in the opening moved further down and closer to the bondtech gears themselves? Or do you mean reduced diameter only?

If you haven't yet, I'd strongly suggest trying with my N3 parts - flexible filaments shouldn't really be limited by the path above the bondtech gears as long as you're not retracting several millimeters like a madman.... I've tested with retraction on, set to 1mm, and TPU printed just fine.

Re: Fix for Squeaky Extruders, especially when printing PETG

I don't think that it's physically possible for PTFE (Teflon) to cause a friction/rubbing squeak

Turns out I'm wrong about this part - I cut some Capricorn XS tubing last night, and it did certainly squeak against a utility knife blade. This might be due to some of the additives in the tubing (it's not pure PTFE), but I stand corrected nonetheless. However, while the tube squeaked when cut, it had a different tone or sound than the distinct PETG/PETG friction sound.

Re: Fix for Squeaky Extruders, especially when printing PETG

Sorry if this is a very noob question. I'm new to 3d printing and the mk3 is my first printer that I received a few weeks ago. I have significant "squeaking" just as in your video on mine using the PLA that came with my printer. Will printing these components help me for PLA as well? Thanks!

Re: Fix for Squeaky Extruders, especially when printing PETG

Will printing these components help me for PLA as well?

It's possible, but unfortunately I can't say 100% for sure! I think that if you've eliminated everything else (it's not belts, not bearings, not bondtech gears, and the gears are properly lubed), and the squeak happens only when the extruder motor is moving or switching direction, there's a really good chance they'll help.

There's no real downside I can see to using these parts, and filament is definitely easier to load and unload.

Note: the parts linked above are for Mk3 printers only - if you recieved a Mk3S, or want to use the C1/R4/Mk3S parts with the Mk3 filament sensor, see the parts linked here: https://www.myminifactory.com/object/3d-print-86329

Thanks, and good luck! If you do try the parts and they help (or if they don't) please reply again here so you can share your feedback.