Category: Underextrusion

If you are a 3D printing enthusiast, you may have encountered the frustrating problem of a clogged nozzle. This can happen when the filament gets stuck or melted inside the nozzle, preventing the extruder from pushing out more material. A clogged nozzle can ruin your print and waste your time and filament.

But what if the problem is not really a clogged nozzle, but something else? I will explain how improper tension on the extruder can masquerade as a clogged nozzle, and how to fix it.

The extruder is the part of the 3D printer that feeds the filament into the hot end, where it is melted and extruded through the nozzle. The extruder has a spring-loaded mechanism that applies pressure on the filament, pushing it against a drive gear or a hobbed bolt. This pressure is called tension, and it is essential for the extruder to work properly.

If the tension is too low, the drive gear or the hobbed bolt may slip on the filament, causing under-extrusion or skipping steps. This can result in gaps, holes, or weak layers in your print. If the tension is too high, the drive gear or the hobbed bolt may dig into the filament, causing over-extrusion or grinding. This can result in blobs, strings, or jams in your print.

Both under-extrusion and over-extrusion can look like a clogged nozzle, because they affect the amount and quality of material that comes out of the nozzle. However, a clogged nozzle is usually caused by a different issue, such as a dirty nozzle, a partial blockage, or a heat creep.

So how can you tell if your problem is really a clogged nozzle, or an improper tension on the extruder? Here are some tips:

  • Check your filament. If you see signs of grinding or slipping on the filament, such as flat spots, gouges, or dust, then your tension is likely too high or too low.
  • Check your extruder. If you hear clicking or popping noises from the extruder, then your tension is likely too high or too low.
  • Check your nozzle. If you see material oozing out of the nozzle when it is not printing, then your tension is likely too high. If you see no material coming out of the nozzle when it is printing, then your tension is likely too low.
  • Do a cold pull. A cold pull is a technique to clean your nozzle by heating it up, inserting a piece of filament, letting it cool down, and then pulling it out with force. If you see a clean tip on the filament after doing a cold pull, then your nozzle is not clogged.
  • Adjust your tension. Depending on your extruder model, you may have a screw, a knob, or a lever to adjust the tension on the filament. You want to find a balance between too much and too little pressure. A good rule of thumb is to make sure that the drive gear or the hobbed bolt leaves slight marks on the filament, but not deep enough to damage it.

One of the common problems that 3D printer users face is under-extrusion, which means that not enough filament is coming out of the nozzle. This can result in poor print quality, gaps, and weak layers. One of the possible causes of under-extrusion is that the filament is not heated up to its melting point, which means that it cannot flow smoothly through the nozzle.

How can you tell if your filament is not hot enough? Here are some signs to look out for:

  • The filament is curling or bending as it comes out of the nozzle, instead of forming a straight line.
  • The filament is making a clicking or grinding noise as it is pushed through the extruder.
  • The filament is brittle and breaks easily when you bend it.
  • The print surface is rough and uneven, with blobs and strings.
  • The print layers are not adhering well to each other, and the print is weak and fragile.

If you notice any of these signs, you may need to increase the temperature of your nozzle. You can do this by adjusting the settings on your 3D printer’s control panel, or by using a slicer software to set the temperature for each layer. The optimal temperature for your filament depends on the type and brand of filament you are using, as well as the ambient temperature and humidity. You can check the recommended temperature range on the filament spool or on the manufacturer’s website.

However, be careful not to overheat your filament, as this can also cause problems such as clogging, oozing, and burning. You can tell if your filament is too hot if:

  • The filament is dripping or leaking from the nozzle when it is not printing.
  • The filament is bubbling or smoking as it comes out of the nozzle.
  • The filament is discolored or charred.
  • The print surface is glossy and smooth, with no details or texture.
  • The print layers are sagging or warping, and the print is deformed.

If you notice any of these signs, you may need to lower the temperature of your nozzle. You can do this by following the same steps as above, but in reverse.

You can also use a temperature tower test to calibrate your nozzle temperature for different filaments. A temperature tower is a 3D model that prints at different temperatures along its height, so you can compare the results and choose the best one. You can find many temperature tower models online, or create your own using a slicer software.

Have you ever started a 3d print, only to come back a few hours later to find that your nozzle in midair with nothing being extruded from it? Then you fix the clog, only to have the same thing happen? If so, you might have encountered heat creep. This is when heat from the hot end travels up the filament and causes it to melt before it reaches the nozzle. This can result in clogs, underextrusion, and poor print quality.

How can you recognize heat creep? Some symptoms include:

  • Filament grinding or slipping in the extruder
  • Filament oozing out of the nozzle when not printing
  • Filament snapping or breaking during printing
  • Inconsistent extrusion or gaps in layers
  • Nozzle jamming or clicking noises

Heat creep can be caused by various factors, such as:

  • Printing at too high temperature
  • Poor cooling of the hot end or heat sink
  • Improper insulation of the hot end
  • Faulty or dirty fans
  • Low-quality or incompatible filament

Fortunately, heat creep can be prevented or fixed with some simple solutions, such as:

  • Lowering the printing temperature to the minimum recommended for your filament
  • Increasing the cooling of the hot end or heat sink with better fans or ducts
  • Adding thermal paste or silicone socks to the hot end to improve insulation
  • Cleaning or replacing the fans regularly to ensure optimal airflow
  • Using high-quality and compatible filament that matches your printer settings

It never fails. It’s always the simple things that keep us humble.

I like to tinker, to optimize, and to get the best parts that I can out of my 3d printers. In doing so, I’m always upgrading, experimenting, and messing with settings.

At the end of the day, though, it’s important for me to remember that I’m just heating up plastic and squeezing it through a nozzle and that there are some fundamental things that need to be in place for that to happen. Sometimes, I lose track of that fundamental concept.

I upgraded my extruder a little while back. A better extruder means better parts, right? Well, that was true, for a little while. Over the weekend my 3d printer stopped extruding filament. I ended up thinking it was a clogged nozzle and completely took apart the hotend to find out what the problem was. It turned out to be that there was no problem…at that end.

I turned back to the extruder and took a closer look. After taking it apart and putting it back together about 600 times, it seemed like, I finally realized that the gears weren’t meshing properly. When I upgraded my extruder, I had aligned the gears close enough that they functioned properly at first. But after a while, the misalignment had caused my plastic gear to become worn and eventually stop extruding. New plastic gear ordered and old extruder put on the printer while I wait for the gear.

Back to basics. If you want to extrude something, your gears have to mesh well.

The extruder is the part of your printer that pushes the filament through the nozzle and melts it to create the layers of your 3D print. If the extruder is not working properly, you may encounter problems such as under-extrusion, over-extrusion, clogging, stringing, or poor adhesion. Here are some steps you can take to diagnose if your printer has an issue with the extruder:

  1. Check the temperature of the extruder. The temperature should match the recommended range for the type of filament you are using. If the temperature is too low, the filament may not melt enough and cause under-extrusion or clogging. If the temperature is too high, the filament may ooze out of the nozzle and cause over-extrusion or stringing. You can adjust the temperature using the printer’s settings or a slicer software.
  2. Check the tension of the extruder. The tension is the force that the extruder applies to the filament to push it through the nozzle. If the tension is too loose, the extruder may not grip the filament well and cause under-extrusion or skipping. If the tension is too tight, the extruder may deform or grind the filament and cause over-extrusion or clogging. You can adjust the tension by tightening or loosening the screws on the extruder.
  3. Check the alignment of the extruder. The alignment is the position of the extruder relative to the nozzle and the print bed. If the alignment is off, the extruder may not deposit the filament evenly and cause poor adhesion or warping. You can check the alignment by printing a test pattern and measuring the distance between the nozzle and the print bed at different points. You can adjust the alignment by leveling the print bed or adjusting the height of the nozzle.
  4. Check for any debris or damage in the extruder. The debris or damage may be caused by dust, dirt, filament residue, or wear and tear. If there is any debris or damage in the extruder, it may obstruct or interfere with the flow of filament and cause clogging, jamming, or inconsistent extrusion. You can check for any debris or damage by inspecting the extruder visually or using a needle or a wire to poke through the nozzle. You can clean or replace any parts that are dirty or damaged.

Do your parts look like biscuits? If you are new to 3D printing, you might have encountered some problems with your prints. One of the most common issues is when your prints look spongy or porous, instead of smooth and solid. This can affect the appearance, strength and functionality of your 3D printed objects. I will explain why this happens and how you can fix it.

The main reason why your 3D prints look spongy is because of under-extrusion. Under-extrusion is when your printer does not extrude enough filament to fill the gaps between the layers or the perimeters of your model. This can be caused by several factors, such as:

  • A clogged nozzle that prevents the filament from flowing smoothly
  • A worn-out extruder gear that does not grip the filament properly
  • A low extrusion temperature that makes the filament too viscous to melt
  • A high printing speed that does not give enough time for the filament to adhere to the previous layer
  • A low infill percentage that does not provide enough support for the top layers
  • A faulty slicer setting that does not calculate the correct amount of filament needed

To fix the problem of under-extrusion, you need to identify and eliminate the root cause. Here are some steps you can take to troubleshoot and improve your 3D prints:

  • Clean your nozzle regularly with a needle or a wire brush to remove any debris or burnt filament
  • Replace your extruder gear if it shows signs of wear and tear or slippage
  • Increase your extrusion temperature gradually until you find the optimal value for your filament type and brand
  • Reduce your printing speed to allow more time for the filament to bond with the previous layer
  • Increase your infill percentage to provide more support and stability for the top layers
  • Check your slicer settings and make sure they match your printer specifications and filament characteristics

By following these tips, you should be able to reduce or eliminate the sponginess of your 3D prints. Remember to always test your settings on a small and simple model before printing a large or complex one. Happy printing!