How to Fix Under-Extrusion in 3D Printers – Not Extruding Enough

A problem that I’ve experienced with my 3D printer is an inconsistent extrusion from the nozzle with a print, which looks bumpy. I wondered how to fix this problem, so I researched exactly how to fix a 3D printer that stopped extruding consistently and got some answers that I’ll share with you.

The best way to fix a 3D printer that is extruding inconsistently from the nozzle is to clear any clogs or jams in the extrusion system, whether that’s in the extruder gears, Bowden tube or nozzle. You should also make sure your filament spool can rotate freely and use a larger layer height.

There are other factors that contribute to your 3D printing extruding inconsistently, which will be explained further in this article.

Why Does My 3D Printer Stop Extruding Consistently?

Bad Filament Pathing or Tangled Filament

If the filament is wounded improperly or the threads are not rolled off by the 3D printer correctly, the filament can get stuck resulting in uneven extrusion.

When the filament spool gets jammed, it produces friction which usually loses its grip on the material when fed into the printer. This results in lower emissions through the reduced flow of the material.

If the filament spool is empty, you will have to load the spool before moving forward. If the spool is not empty, you should check that the filament can easily pass through the Bowden tube.

Check to see if there is much resistance and consider cleaning the tube or applying some lubricant in the pipe.

Extruder Motor Issues

The extruder motor is the most functioning component of the 3D printer. It pushes and pulls the plastic back and forth constantly.

This fast motion requires a current, and if the printer’s electronic components are not cooled enough, the extruder motor will be overheated.

In this case, the motor controllers usually have a thermal cutout which causes the controller to stop working until the temperature goes down. So turn off the printer for some time allowing components to cool down.

Slipping of the Extruder Gears

If your extruder gears have start to wear out over time, it can’t get the same grip that it needs on the filament to extrude it through smoothly. I would check on your extruder gears and look for noticeable blunt areas on the teeth.

A good dual-geared extruder or a fresh extruder should correct this easily.

Layer Height Too Low

The layer height has a significant impact on 3D printing. If you are trying to print something at a low layer height, there will be very little room for the plastic to come out of the nozzle. Make sure to use the appropriate layer height for the printer.

You can change the layer height directly in your slicer software which has different methods depending on your program, but it should be fairly easy to operate.

Increase your layer height gradually through trial and error, and you should be able to eliminate the problem of not extruding during the print if this is your cause.

Inaccurate Extrusion Width

Like the layer height, extrusion width can also cause problems. Different extruders have different extrusion width, so be sure to choose the right extruder and assign the right extrusion width to get a silky and smooth 3D print.

It becomes difficult for the printer to extract material if the width of the extrusion is significantly less than the diameter of the nozzle.

According to the manufacturers, the perfect extrusion width is 100% to 150% of the diameter of the nozzle. You should be able to find these in your slicer using the search function, or by expanding the basic/advanced level view of your settings.

Extruder Jammed or Clogged

If the printer is not extruding enough, the extruder may be clogged. If this happens, check that the filament is clean and the spool is dust-free. If there is a lot of dust on the reel, it can block the extruder as it accumulates inside the nozzle.

In some cases, the plastic isn’t extruding properly, so you can try extruding some plastic manually. If you are still facing issues, you may need to clean the nozzle by following the instructions provided in the video below by Thomas Sanladerer.

Bad Quality Filament

A filament of inadequate quality is one of the most common reasons that cause printers not to extrude enough. Bad quality filaments contain some additives or have unstable filament diameters that affect the consistency of the flowing plastic.

The filament of high quality includes a dryer in the packaging because PLA absorbs the moisture from the air and affects the quality of the printer. If you think this is the problem, try replacing the existing spool with a new, sealed spool of better quality.

If your PLA has absorbed moisture and starts popping while being heated to high temperatures, some people have fixed this by placing it in an oven at a low heat. You can also use a food dehydrator to do the same job.

Heat Creep Issues

Heat creep is a form of a blockage or clog within your extruder system. It occurs because of a temperature imbalance, where the heat actually travels a little further than it’s supposed to into the PTFE tube.

What then happens is filament because softer within the filament tube and starts to get pushed around the outer extrusion path, leading to extrusion problems.

This can occur if your PTFE tube has worn out, or you have a bad heatsink which doesn’t negate heat away from this area.

How to Fix Inconsistent Extruding From Nozzle?

Patience is something that you will need to consider 3D printing as a profession or hobby. None of the solutions mentioned in this article is complicated. But you will need the patience to clean, remove, and fix the problem efficiently.

Once you find the cause of your inconsistent extrusion, the solutions becomes a lot easier to figure out as illustrated above.

The best intervention is to buy good quality filaments, make sure that the filaments and nozzles are clean, and review the best printer settings for your filament.

If you are experiencing under extrusion at a certain height, you want to check that your Bowden isn’t getting pinched at those higher heights. One thing you can do is to raise your Z-axis through the control box on your printer and see if there are any issues.

Installing a longer Bowden tube should fix this problem. The Creality Capricorn Bowden PTFE Tubing from Amazon is a good choice for your printer.

Increasing your printing temperature is another method that has worked for many users to fix under extrusion at a certain height, so I’d try raising your temperature to see if that helps.

You may be experiencing under extrusion after a nozzle change, retraction, on small parts or even at the start of a layer. There are fixes for each of these specific with the right knowledge.

One of the main reasons why you experience under extrusion after a nozzle change is due to not tightening your nozzle against the heatbreak. If you end up leaving a small gap, you can start to have melted filament slowly leak out of this area.

I’d also make sure to clean out your extruder gears of dust and debris. Also, make sure you don’t over tighten the gears on your extruder, and you want it to be tight enough to have a fairly good grip.

If you are getting under extrusion after retractions, I’d try increasing the retraction length as well as adding some “Retraction Extra Prime Amount” in Cura or your chosen slicer to 0.25 – 0.5mm. Increasing this setting means you add more pressure in the nozzle chamber after a retraction.

It can take a little bit of testing, since larger values can results in blobs on your prints.

Sometimes people get under extrusion on small parts which can be a pain. For one user, the cause was through a badly wound spool of filament that was twisting and causing strong resistance in the Bowden tube. I’d check for the filament pathway and make sure things are going through smoothly.

In some cases, you may just have to change your nozzle to a fresh one, especially if you have never changed your nozzle and you use a brass one. With standard filament, brass nozzles can hold up pretty well, but after a few hundred hours of printing, or from scraping on the build plate, a change can be in order.

If you are getting under extrusion at the start of a layer, check that your “Retract at Layer Change” setting is unchecked as this can decrease the pressure in the nozzle chamber. I’d also try increasing your “Retraction Extra Prime Amount” to a value around 0.5 – 0.8mm.

Another solution for this issue that has worked for many users is to try turning “Combing Mode” off in Cura or your slicer.

How Can You Tell if a Nozzle is Clogged?

The most obvious symptom is that the filament does not come out of the nozzle properly. The filament is curling or sticking to the tip of the nozzle. There will be a sound or clicking from the extruder. The other signs include:

  • The extrusion is looking inconsistent.
  • A lot of dust around the extruder motor.
  • The print is not silky or smooth.
  • Dotted lines around the print.
  • The printed parts are too fragile.
  • The filament spool has stopped turning.

How Do You Fix a Clogged Nozzle?

When you have a clogged print nozzle, you can use a number of cleaning techniques to resolve the issue depending on the material that is causing the hassle.

The method always recommended by the experts is to use cleaning filaments regularly, but this method is only suitable for partially clogged nozzles and will not open the completely clogged issue. Below are some other techniques to fix a clogged nozzle.

  • Use a brass wire brush to clean the dirt from the nozzle.
  • Acetone is well known to dissolve thermoplastic. Cleaning the nozzle with an acetone bath helps to remove unwanted particles and will fix the clogged nozzle.
  • The other way to fix a clogged nozzle of 3D Printer is to clear it using an acupuncture needle.
  • Heat the nozzle to 250 degrees Celsius and insert the cleaning filament into the nozzle until the nozzle is completely free of old threads. Remove the filament and reheat the nozzle to remove tiny filament particles and then clean the nozzle thoroughly.

It’s usually easy to distinguish under extrusion vs over extrusion for your 3D printer. You’ll see that your 3D prints have more gaps and are generally weaker than usual if you have under extrusion.

Over extrusion is also clear to see, where you have plastic squashed together, leading to a low quality 3D print that isn’t very dimensionally accurate. It is most visible in the outer dimensions of your 3D print.

How To Clean & Prevent 3D Printer Jams

There are various solutions to fix 3D printer jams, but the ideal solution is to prevent it from clogging. Below are the tips that will help you to clean and deter 3D printer jams in the future.

Thoroughly clean the nozzle when switching between filaments.

  • Print at the right temperature to avoid electronic components overheat
  • Use a clean filament of high quality
  • Calibrate your printer bed at the right level
  • Set an optimal and perfect layer height of 50% to 70% of the nozzle height, which is recommended by the experts.
  • Try to store your spool in an airtight bag because this will not only prevent dust from accumulating but also prevents the absorption of the moisture from the air.

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