Overview of troubleshooting my MK3 extrusion issues  

Overview of troubleshooting my MK3 extrusion issues

Over the last couple of weeks I ran into major issues with extrusion on my MK3. The thing is, I had been printing for months without a problem so I figured it had to be something I caused.

I did a full writeup on my problem and the steps I went through to resolve it in the stack exchange 3D Printer site:

https://3dprinting.stackexchange.com/questions/6183/issues-with-proto-pasta-filament-extruding-on-prusa-mk3#answer-6265

I wanted to repost it here just in case it helped anyone else out or gave anyone ideas/tips on how to troubleshoot the problems they ran into.

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tl;dr

I had a dragging idler pulley that was causing extrusion issues. Opening the idler pulley door and working it a bit with my finger resolve the issue.

The detailed explanation

So after two weeks or so of troubleshooting, banging my head, taking a break, and coming back to it I'm finally getting good prints again.

I do believe the original problem started with the clogged nozzle due to the bore hole diameter being too small for the glitter filament as mentioned by Axel in the post comments (a bit rude about it, but still probably true), but there were other issues that I ran into.

Troubleshooting steps

General cleaning
After I switched back to inland filament (which had been working fine for months) I was still having extrusion issues. At this point it was due to the clog (I suspect).

I tried several steps to unclog the nozzle including [the steps suggested by prusa support]( https://help.prusa3d.com/l/en/article/WWVRzOY1dX-clogged-nozzle ) and [cleaning techniques suggested by Tom]( ) amongst other places.

I also picked up [a couple of pencil brushes on amazon]( https://www.amazon.com/gp/product/B00CWDO1XU/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 ) including a small brass brush that's perfect for cleaning off the extruder pulley teeth.

Cold pulls
During these steps, I think I introduces the second problem without being aware of it. I perform a bunch of cold pulls (explained by Tom in his video and other videos and posts). During one of these cold pulls I forgot to loosen the MK3's idler pulley door before tugging. Once I noticed it I loosened the door, but I think that tug may have affected the idler pully getting it a bit gritty (I don't know _how_ it would have done that, but it's my current guess).

At this point I was still getting extrusion issues and didn't think about the idler pulley being the issue, so thinking that the nozzle was still the issue I ordered a second E3D nozzle and some Ethyl Acetate which dissolves PLA.

Notes on Nozzles and Ethyl Acetate

E3D nozzles

A couple of helpful points I learned while researching these purchases.

There are a _lot_ of cheap nozzles that say they work on the E3D, but be sure to read the comments from whatever nozzle you're looking at because apparently a lot of them either don't fit or don't print well.

I ended up purchasing a replacement nozzle sold directly from E3D to be safe.

Ethyl acetate

As far as the Ethyl Acetate, I was having a hard time finding it online when looking for it as a solvent without having to purchase the chemical in a giant jar. I didn't want to buy a jug, I only needed a bit.

After doing a bit more research I found out that it's the same chemical that [entomologists use to kill insects for preservation]( https://en.wikipedia.org/wiki/Ethyl_acetate#Entomological_killing_agent ) and when you look for the chemical from that context you can find it sold in much smaller quantities. I was able to find [a small jar of ethyl acetate on amazon for 7 dollars]( https://www.amazon.com/gp/product/B0755JYFJS/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 ). Smaller, safer, and cheaper.

Finding the actual problem

Once the nozzle and ethyl acetate came in I pulled off the old nozzle, dropped it into the ethyl acetate to soak, put the new nozzle on (per the instructions from prusa's website), and reaccelerated the printer just to be safe. I tried printing a test block and it seemed better, so I then tried a larger print and while the printed model seemed better, it was still obviously having extrusion issues and crumpled in my hand.

With the nozzle ruled out, I started looking elsewhere on the printer. After watching [a video from the 3D Printing Nerd on extrusion issues he was having on his MK3]( ) I decided to check the extruder pulleys. When I tried to open my extruder idler pulley door I noticed I couldn't actually get it open; it seemed to be stuck on the bottom. I tried to free the bottom of the door, but couldn't without forcing it past my comfort level. Instead, I unscrewed [the top of the pulley door]( https://manual.prusa3d.com/Guide/5.+E-axis+assembly/510?lang=en#s8310 ) to remove it.

From here I noticed two things, I didn't get the pulley teeth as clean as I though I had before and the idler pulley's mounting rod was extended just a bit (which is what was causing it to stick at the bottom). I adjusted the rod and put the door back on. It was printing better but still had extrusion issues.

I then watched the pulley during the filament loading and notices that while the extruder stepper motor was turning smooth, the idler pulley was stuttering a bit while turning. I imagine those little stops and starts were what was causing the extrusion issue.

I opened the idler door back up and worked the idler pulley a bit with my finger. It started to spin free (maybe there was gunk in it? maybe it was rubbing a bit against the mount? ¯\\_(ツ)_/¯), so I closed the door and screwed it back in tight.

Ran a test print -> perfect.

I've run several prints increasing in complexity and it seems like I'm back to printing well.

How I introduced my own problem

As I noted above in the explanation, I think I introduced the problem during a cold pull where I forgot to loosen the idler pulley door. I know this explanation is super verbose, but when looking around, even after fixing the printer, I haven't really seen many people noting that on the MK3 you should make sure the door isn't screwed down when performing the cold pull. It's def a common sense move, but I don't see it mentioned as a potential for introducing a problem.

Also I didn't see a dragging idler pulley as a possible cause of extrusion issue so I thought I'd note it here as well.

Hopefully if anyone else has a similar problem on the MK3 this will be a source of help.