The Ender 3 “Clunk”, “Clack”, “Snap”, “Bang” Problem

If you are an owner or user of Crealty’s Ender 3, 3D printer you may experience the dreaded “Clunk”, “Clack”, “Snap”, or “Bang” coming from around the filament feeder motor. For simplicity let’s call it “the clunk.” If you hear the clunk occasionally it’s likely not a problem. But if it starts happening frequently, then something is not right and it should be looked in to. The good news is it is not as bad as it sounds, so long as it’s fixed in short order.

Ender 3 Print Head (Copyright Author)

I’ve experienced the clunk five different ways, and in my case three were interrelated, but they all can happen independently of each other. Let’s look at each one:

1) Nozzle temperature too low. The sample spool of filament provided with our Ender 3 was simple PLA. When that ran out we bought PLA+ and we assumed it used the same nozzle temperature. Wrong! Ordinary PLA runs about 200C, but the PLA+ we bought specifies 205C to 225C. When the temperature is too low, the filament does not get fluid enough to flow through the nozzle as it should, and the feeder motor tries hard to push it, but at times it fails. Clunk. The fix is simple: use the correct nozzle (and bed) temperatures for the filament you are using. You can set the temperature in most slicers (preferred), or you can use the “Tune” selection from the Ender 3’s menus to manually set the temperature every time you print.

Ender 3 Print Head & Feeder Mechanism (Copyright Author)

2) Loose brass toothed feeder wheel. Our first clunk happened because the set screws on the toothed feeder wheel came loose (see picture below). The symptoms included clunking when the filament changed direction, and it got louder over time. The second symptom was the toothed wheel began spinning on the motor shaft, the filament stopped feeding, and the print stopped printing. In this case the fix was also pretty simple; I placed the toothed wheel back into position and tightened the two set screws — first the one on the stepper motor “flat”, then the other one. It is best to attend to this right away, because if you act before the toothed wheel comes completely loose, the fix is simply to tighten the set screws. But if the filament stops moving inside print head, it can bake and harden requiring disassembly of the print head for cleaning. More stuck filament info below.

3) Clogged nozzle. A clogged nozzle can happen many ways, the most common being from use of dirty, low quality, or cheap filament. The fix for these is easy, don’t use contaminated or poor quality filament — it’s not worth it.

Clogged nozzles can also happen as a byproduct of a loose toothed feeder wheel. When filament is stuck in the print head, it becomes difficult to remove because a ball forms on the end and does not want to pass back through the tube or other small openings of the feed system. As a result of its reluctance to come out, I released the Teflon guide tube from the Bowden coupler on top of the print head. That made it possible to pull the baked filament out of the print nozzle, and after I snipped off the ball from the end of the filament, it was possible to remove the filament from the rest of the feed system. I put the Teflon feed tube back into the Bowden coupler and the printer worked almost normally with only a few clunks now and again… for a while. But this added a new problem and led to another way to get the clunk.

Ender 3 Feeder Mechanism — Closeup (Copyright Author)

4) Mis-installed Teflon Bowden feeder tube. After the above clogged nozzle fix, the filament was still difficult to remove from the feed system, and the constant clunking came back quickly. After a bit of research I found that a Teflon feed tube not fully seated against the top of the brass print nozzle could cause… the clunk. That mis-install also makes for difficult filament removal. I noticed a scar on the Teflon tube where it had been seated before, and it was clearly several millimeters out of position.

When the feed tube is not fully down against the top of the brass nozzle, melted filament fills the gap between the end of the Teflon Bowden tube and the top of the nozzle, forming a doughnut around the filament. The plastic that makes up the doughnut does not get pushed through and out, and it bakes into a hard mass. That mass makes it difficult for the feeder motor to push the filament through, causing the clunk. When cooled, the baked plastic doughnut sticks to the filament locking the filament in place. There are many excellent videos on how to clean the print head, so I won’t attempt to repeat that here. The fix takes some more advanced technical skills, it has to be done “hot”, and doing it wrong can cause damage, so if you don’t have that skill, find a friend who does. But in general, the nozzle and the Bowden coupler are removed, the doughnut and half-baked gunk is pushed out, the nozzle is cleaned out, then the print head is re-assembled to specs, ensuring that the dreaded tube-nozzle gap is avoided.

Vitruvian Hummingbird (Copyright Author)

5) Print table to brass nozzle gap is too small. Setting the gap between the pointy end of the nozzle and the work table is important. If the gap is too big, it won’t cause the clunk, but your work probably won’t stick to the table, resulting in a toppled print. If the gap is too small, the nozzle is partially blocked creating back pressure in the feed system resulting in clunking. The fix is easy, set the table-nozzle gap carefully per recommendations based on your nozzle size, print speed, filament type, etc., but for most printing with commonly used PLA, a table to nozzle gap setting of 0.1 mm (or the thickness of ordinary paper) is good.

There are probably other ways to get the clunk, such as a bad motor or driver board, but I’ve not experienced those (knock on wood), and my internet research indicates those are not common issues.

OK Dear Reader, those are all the ways I’ve experienced getting, and fixing, the dreaded Ender 3 clunk (so far). Until next time, happy printing!



Tech, DIY, Business, & Lifestyle Content Creator on YouTube

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store